Selection of antagonistic actinobacteria for Fusarium graminearum control

Selection of antagonistic actinobacteria for Fusarium graminearum control | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Short Report Selection of antagonistic actinobacteria for Fusarium graminearum control Yuri Borges Véras, Heloísa Giacomelli Ribeiro, Sueli Teresinha Van Der Sand This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9032242/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 10 You are reading this latest preprint version Abstract Fungi of the genus Fusarium cause damage in different types of crops such as tomatoes, onions, bananas, among others, causing different diseases such as wilt disease or Fusarium Head Blight (FHB). Recent studies show that Fusarium graminearum has a high resistance to fungicide and alternative treatment needs to be searched. There are different ways to treat diseases caused by Fusarium , between them, the most relevant is the use of biological control agents. The use of actinobacteria as a biological control agent is considered promising, due to the fact that the most important and known characteristic of this bacteria is the production of secondary metabolites and bioactive compounds. In the present study, eleven actinobacteria isolates were identified by morphological characteristics and submitted to antifungal assay against two isolates of Fusarium graminearum . As a result of the preliminary identification one isolate was identified as Nocardia spp. , seven isolates as Streptomyces spp. and three remained unidentified morphologically. The antagonistic assay was performed using the plate confrontation method, against the two strains of Fusarium graminearum . The isolate LMAF, previously identified as Streptomyces avidinii , showed activity against both Fusarium graminearum isolates. The relation between the pathogen and the Streptomyces avidinii LMAF remain unsure, due to the fact that it can be direct, where the isolate is producing substances that control the growth, or indirect, where both are competing for nutrients and space. Both cases lead to the potential use of isolate LMAF as a biological control agent. Actinobacteria Biological Control Morphological identification Phytopathogenic fungi Antifungal activity Figures Figure 1 Figure 2 Introduction The soil is a diverse environment and shelters an ecosystem, mainly composed of microorganisms. Bacteria, Archaea and Fungi play a fundamental role in soil maintenance, because it recycles organic matter through metabolic processes⁠. Actinomycetota stand out as one of the most prevalent phyla within the soil microbiota, frequently exhibiting high relative abundance in subterranean environments. They are responsible for the maintenance of soil’s carbon reserve and macronutrients through extracellular enzymes that play a fundamental role in organic matter degradation⁠ [ 1 , 2 , 3 ] . Actinobacteria belong to the Actinomycetota phylum, considered one of the biggest taxonomic units among bacteria. They are Gram-positive bacteria that contain high levels of guanine and cytosine (GC) in its genome [ 4 ] ⁠. They grow in a branched manner through the extension of their hyphae, forming mycelial structures and reproduce asexually through spores [ 5 ] ⁠. Its spore chains can present different conformations (short, long, spiral, etc.) and, through optical microscopy, these chains can be used for morphological identification. Actinobacteria are renowned for their prolific capacity to synthesize a diverse array of secondary metabolites and bioactive compounds of significant biotechnological value [ 6 ] ⁠, establishing them as a cornerstone of research across multiple applications. In the pharmaceutical industry, these secondary metabolites are indispensable, as the structural diversity of the substances produced encompasses a vast majority of clinically relevant antibiotics [ 7 ] ⁠. Furthermore, within the agricultural sector, their metabolic repertoire plays a critical role in modulating microbial ecosystems; specifically, Actinobacteria serve as potent biological control agents by suppressing the proliferation of various phytopathogens, thereby safeguarding plant health and enhancing crop productivity [ 8 ] . Fungi of the genus Fusarium are members of the phylum Ascomycota, which has more than 1500 species. They can cause diseases in different types of crops such as onions, tomatoes, bananas, among others [ 9 ] . A known way to deal with Fusarium contamination, as it is less harmful to the environment and human consumption, is the use of biological control agents [ 10 ] . The aim of the present work is to select actinobacteria with the potential to be used as biological control agents against Fusarium graminearum . Material and Methods Isolates In this work, 11 isolates of actinobacteria named as: Actinobacteria LMAF, LMA 1, LMA 2,LMA 3, LMA4, LMA 5, LMA 6,LMA 7,LMA 8,LMA, 9, LMA 10 (Table I) were tested against Fusarium graminearum isolates. The actinobacteria were isolated from soil of the Farroupilha park (located in the city of Porto Alegre, Rio Grande do Sul, Brazil) and belong to bacteria library of the Laboratório de Microbiologia Aplicada at the Universidade Federal do Rio Grande do Sul (UFRGS). Morphological characterization of Actinobacteria isolates The morphological characterization of the actinobacteria colonies was carried out based on the International Streptomyces Project [ 11 ] ⁠ using the International Streptomyces Project medium 2 (ISP2) (4 g yeast extract, 10 g malt extract, 4 g dextrose, 15 g agar, 1000 ml distilled water). Actinobacteria were streaked in Petri dishes with ISP2 medium and then incubated at 28ºC for 7 days. The following parameters were analyzed: the color of the colonies on the substrate, color of the spores in the aerial mycelium and edges of the isolated colonies. Images of the colonies were captured with a 50 megapixel camera. Microstructure morphological characterization To observe the microscopic structures of actinobacteria spore chains, microcultures were carried out in ISP2 and Starch Casein Agar (SCA) culture media (2 g KNO3, 2 g NaCl, 2 g K2HPO4, 0.05 mg MgSO4, 0.01 g FeSO4, 0.02 g CaCO3, 10 g starch, 0.3 g casein, 15 g agar, 1000 ml distilled water). The microculture plates were incubated at 28ºC for 7 days [11´] ⁠. The morphology of the spore chains were evaluated for identification at genus level, according to Bergey's Manual of Determinative Bacteriology [ 12 ] ⁠. The images were captured using a camera (MD90 - MShot) attached to the microscope. Antifungal assay Actinobacteria samples were previously prepared in SCA culture medium. The fungi were previously incubated in Potato Dextrose Agar (PDA) culture medium (1000 ml distilled water; 140g potato broth; 15g Agar; 10g Dextrose). Two strains of Fusarium graminearum were used, named FUG4 and FUG09M134. To observe the antifungal activity of actinobacteria against de Fusarium strains, the plate confrontation method was used. For this purposes plates with PDA medium were inoculated at the center with a fungal agar plug, and at equidistant points (2.5cm) from the center four actinobacterial agar plugs were inoculated. The triplicate samples were incubated at 28ºC for 7 days, so that the fungal growth radius could be analyzed, according to Zou et al., (2021)⁠. The percentage of inhibition was calculated with the formula: Inhibition = [(C - T) / C] x 100, where C is the growth of the fungus in control, and T is the growth of the fungus in treatment. Results and Discussion The morphological characterization of the eleven actinobacteria isolates was conducted by growing them in ISP2 medium. During this process, four different colors were observed in the aerial mycelia, three different colors for the colonies, and two types of edges were observed in all colonies (Table I). Actinobacteria belong to a very diverse group of bacteria is comprised most of soil microbiomes. It has been estimated that only 10% of the known actinobacteria have been isolated from soil. Many of these actinobacteria are found in rhizospheric soil, where they can be associated with plant roots and can provide protection against fungi and other microorganisms [ 14 ] ⁠. Actinobacteria have the ability to produce secondary metabolites and can be used as biological control agents. Therefore, they are a group of great importance for the agricultural field, as they can help to combat plant diseases [ 13 ] ⁠. Due to the high diversity of these microorganisms, it is necessary to identify this group in order to achieve more accurate results. Regarding the microstructure morphological characterization, according to the results obtained the actinobacteria isolate LMA 7 did not form spore chains; instead, fragmentation of the aerial mycelium was observed (Fig. 1 c). Isolates LMA 2, LMA 3, and LMA 10 did not form enough spore chains for characterization through morphology of the spore chain. All other isolates were similar in terms of their shape and number of spores (Fig. 1 d), with small variations in the angle of the spiral. In this study, SCA was used as it is a less nutritious culture medium than ISP2, forming colonies more likely to produce spores and secondary metabolites. Microcultures carried out in SCA medium formed less fragmented and more abundant spore chains. Studies show that the morphology of the spore chain is a very important tool to identify actinobacteria [ 15 ] ⁠. In addition, pigment production is an important characteristic of this group, and can be used to help identification [ 14 ] , which is why the color of the colonies and the aerial mycelium were recorded. According to Bergey's Manual of Determinative Bacteriology , seven of eleven isolates are likely to belong to genus Streptomyces , due to their morphological characteristics in microculture such as the formation of spirals in the spore chains. Given the results, a dominance in the occurrence of the genus Streptomyces can be clearly observed. Among different types of habitat, soil is one of the best known for this genus, which has more than 850 species already described [ 7 ] ⁠. Due to its high diversity and abundance in the soil, the number of isolates belonging to this genus is expected to be high. Actinobacteria isolate LMA 7 was identified as Nocardia spp. (Table II) because in addition to not showing spore chains it presented fragmentation of the aerial mycelium. Recent studies showed that this genus is capable of producing antibiotics and can even be effective in controlling Candida albicans [ 16 , 17 ] ⁠. From the eleven isolates tested against both F. graminearum strains in the antifungal assay, one actinobacteria sample, LMAF, showed effectiveness in controlling the growth of both F. graminearum . LMAF showed 33% with FUG4 ( Fig. 2 a ) and 40% of inhibition in the assay with FUG09M134 (Fig. 2 d). Fungi of the genus Fusarium are known to cause Fusarium wilt, among other diseases, which leads to loss of productivity [ 18 ] ⁠. There are different ways to treat diseases caused by Fusarium , such as the use of post-grow copper to treat the disease [ 19 ] ⁠, or pre-seeding treatments with essential oils to reduce the effects of the disease in the fully grown plant [ 20 ] ⁠. A different way to control diseases caused by Fusarium is the use of biological control agents. In the study by Jing et al., (2020)⁠ the use of Streptomyces isolates as biological control agents against banana wilt disease, caused by the fungus Fusarium oxysporum , was demonstrated. Phenotypic and molecular identification of strain LMAF were previously established via MALDI-TOF MS and 16S rRNA gene analysis (using primers pA/pH and the Neighbor-Joining method in MEGA X), showing high similarity with Streptomyces avidinii (accession number: PP410358) (Data not yet published). Biological control agents protect plants from diseases in different ways. Indirectly, they can induce resistance in plants or compete for space and nutrients with the pathogen. Directly, they can parasitize pathogens or produce antibiotics [ 22 ] ⁠. According to the results, the interaction between the potential biological control agent and the pathogen is difficult to determine, since there may be the production of antibiotics or it may just be a competition for space and nutrients. In both possibilities there is interaction; therefore, biological control is plausible. The fungus F. graminearum is part of a complex of species known to cause different types of diseases, such as fusariosis or blight, and affect different types of crops, such as corn, rice and wheat [ 23 ] ⁠. The most common way to combat this fungus is the use of fungicides, but recent studies showed that there is a high occurrence of fungicide-resistant F. graminearum [ 24 ] ⁠. Taking into account the damage caused by F. graminearum , and the great potential of actinobacteria to produce various compounds that can be useful in controlling fungal growth, it is necessary to identify new and different biological control agents, as well as the identification of actinobacteria that can perform this function. According to our results, isolate LMAF, previously identified as Streptomyces avidinii , showed activity against the two F. graminearum tested, which suggests a potential for use as a biological control agent. The use of species of this genus without a fully identification (species level) was shown in the work of⁠ Mattei et al. (2022), where spores of Streptomyces sp. were used as biological control against F. graminearum . Conclusion Isolate LMAF has the potential to be used as a biological control agent. The relationship between actinobacteria and fungi remains undetermined, and may be an indirect interaction, where the bacteria are simply competing for space and nutrients. It also can be direct, where there is production of substances that prevent the growth of fungi. More biochemical, genetic and chemical assays are necessary for more accurate identification of natural products and its production inducers. Thus, the isolate can go through new stages of testing to better evaluate its potential. Declarations Acknowledgements The authors acknowledge the Laboratory of Environmental Microbiology for providing the actinobacterial isolates and infrastructure support. CAPES e FAPERGS for financial support. Funding This research was supported by CAPES and FAPERGS. Conflicts of interest/Competing interests The authors have no relevant financial or non-financial interests to disclose. Ethics approval Not applicable. This study did not involve human participants or animals. Consent to participate Not applicable. Consent for publication The authors affirm that all participants provided informed consent for the publication of the data presented in this manuscript. Availability of data and material The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request. Code availability Not applicable. Declaration of deposition in repositories Not applicable. Authors' contributions All authors contributed to the study conception and design. Material preparation, data collection, and analysis were performed by all authors. The first draft of the manuscript was written by Yuri Borges Véras and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. References Zheng Q et al (2019) Soil multifunctionality is affected by the soil environment and by microbial community composition and diversity. Soil Biol Biochem 136:107521. https://doi.org/10.1016/j.soilbio.2019.107521 Araujo R et al (2020) Biogeography and emerging significance of Actinobacteria in Australia and Northern Antarctica soils. Soil Biol Biochem 146:107805. https://doi.org/10.1016/j.soilbio.2020.107805 Bao Y et al (2021) Important ecophysiological roles of non-dominant Actinobacteria in plant residue decomposition, especially in less fertile soils. Microbiome 9. https://doi.org/10.1186/s40168-021-01032-x Rangseekaew P (2019) Pathom-aree, W. Cave Actinobacteria as Producers of Bioactive Metabolites. 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Front Plant Sci 10. https://doi.org/10.3389/fpls.2019.00845 Del Ponte EM et al (2022) Fusarium graminearum Species Complex: A Bibliographic Analysis and Web-Accessible Database for Global Mapping of Species and Trichothecene Toxin Chemotypes. Phytopathology® 112, 741–751 https://doi.org/10.1094/PHYTO-06-21-0277-RVW de Chaves MA et al (2022) Fungicide Resistance in Fusarium graminearum Species Complex. Curr Microbiol 79:62. https://doi.org/10.1007/s00284-021-02759-4 Mattei V et al (2022) Wheat Seed Coating with Streptomyces sp. Strain DEF39 Spores Protects against Fusarium Head Blight. Microorganisms 10:1536. https://doi.org/10.3390/microorganisms10081536 Tables Table I Colony Morphology Isolate Aerial mycelium color Colony color Edge LMAF Yellow Yellow Irregular LMA 1 Yellow Yellow Irregular LMA 2 White Yellow Round LMA 3 Yellow Yellow Irregular LMA 4 White Yellow Round LMA 5 White Brown Round LMA 6 Light Brown Dark Brown Irregular LMA 7 White Yellow Round LMA 8 White Yellow Irregular LMA 9 Grey Yellow Round LMA 10 Yellow Yellow Irregular Table II Spore chain morphological identification Isolate Spore chain Genus LMAF Spira Streptomyces LMA 1 Spira Streptomyces LMA 2 - W/I LMA 3 - W/I LMA 4 Spira Streptomyces LMA 5 Spira Streptomyces LMA 6 Spira Streptomyces LMA 7 Fragmented mycelium Nocardia LMA 8 Spira Streptomyces LMA 9 Spira Streptomyces LMA 10 - W/I W/I: Without identification Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 17 May, 2026 Reviews received at journal 05 May, 2026 Reviewers agreed at journal 04 May, 2026 Reviews received at journal 04 May, 2026 Reviewers agreed at journal 30 Apr, 2026 Reviewers agreed at journal 29 Apr, 2026 Reviewers invited by journal 16 Apr, 2026 Editor assigned by journal 08 Mar, 2026 Submission checks completed at journal 06 Mar, 2026 First submitted to journal 04 Mar, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9032242","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Short Report","associatedPublications":[],"authors":[{"id":625458963,"identity":"c2a29028-2d39-4d0d-b756-f0976d2959a8","order_by":0,"name":"Yuri Borges Véras","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA30lEQVRIiWNgGAWjYJCCAxCK+eADIMnDR4IWtmQDkBY2EizjMZMA6ySkzuBG7sMDjG02+fz9B8wqv+bYybAxMD98dAOvlnQDoJY0yxk3EtJuy25LBjqMzdg4B6+WNKBfzhw2YLjBcOy25DZmoBYeNmkitPw3kD9/sK1Ycls9sVoqDhgYHEhmY/y47TBhLZJnnjEcSKhINjC8kcYszbjtOA8bMwG/8B1PY/7wwcDOQO78+Y8ff26rtudnb374GJ8WhQNAIgHKYeYBk3iUg4B8AxKH8QcB1aNgFIyCUTAyAQBPj0fKdNIRdQAAAABJRU5ErkJggg==","orcid":"","institution":"Federal University of Rio Grande do Sul","correspondingAuthor":true,"prefix":"","firstName":"Yuri","middleName":"Borges","lastName":"Véras","suffix":""},{"id":625458964,"identity":"ed0ce4d2-b699-4fdf-9d5a-9eb950e7bec7","order_by":1,"name":"Heloísa Giacomelli Ribeiro","email":"","orcid":"","institution":"Federal University of Rio Grande do Sul","correspondingAuthor":false,"prefix":"","firstName":"Heloísa","middleName":"Giacomelli","lastName":"Ribeiro","suffix":""},{"id":625458965,"identity":"2c4d6801-b344-45f4-839d-b9c58e7f3475","order_by":2,"name":"Sueli Teresinha Van Der Sand","email":"","orcid":"","institution":"Federal University of Rio Grande do Sul","correspondingAuthor":false,"prefix":"","firstName":"Sueli","middleName":"Teresinha Van Der","lastName":"Sand","suffix":""}],"badges":[],"createdAt":"2026-03-04 16:08:32","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9032242/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9032242/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":107637190,"identity":"49c66ac4-e1f6-4eab-b971-e829f7c4fd6c","added_by":"auto","created_at":"2026-04-23 12:41:28","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1950069,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003ea\u003c/em\u003e: Isolate of\u0026nbsp;actinobacteria LMA 7; \u003cem\u003eb\u003c/em\u003e: Isolate of actinobacteria LMA 4; \u003cem\u003ec\u003c/em\u003e:\u0026nbsp;Microscopic structure of the aerial mycelium of isolate of actinobacteria LMA\u0026nbsp;7; \u003cem\u003ed\u003c/em\u003e: Microscopic structure of the spore chain of isolate LMA 4.\u003c/p\u003e","description":"","filename":"FIG12.png","url":"https://assets-eu.researchsquare.com/files/rs-9032242/v1/364625714f48c221ab4ff985.png"},{"id":107637208,"identity":"dbb030e7-4116-47fc-a651-5aa3ac55ffc6","added_by":"auto","created_at":"2026-04-23 12:41:37","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":7566618,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003ea\u003c/em\u003e\u003cstrong\u003e: \u003c/strong\u003eAerial mycelium from antibiotic assay of LMAF against fungus FUG4; \u003cem\u003eb\u003c/em\u003e\u003cstrong\u003e: \u003c/strong\u003eVegetative mycelium from antibiotic assay of LMAF against fungus FUG4;\u003cstrong\u003e \u003c/strong\u003e\u003cem\u003ec\u003c/em\u003e\u003cstrong\u003e: \u003c/strong\u003eFUG4 control; \u003cem\u003ed\u003c/em\u003e\u003cstrong\u003e:\u003c/strong\u003e Aerial mycelium from antibiotic assay of LMAF against fungus FUG09M134; \u003cem\u003ee\u003c/em\u003e\u003cstrong\u003e:\u003c/strong\u003e Vegetative mycelium from antibiotic assay of LMAF against fungus FUG09M134; \u003cem\u003ef\u003c/em\u003e\u003cstrong\u003e:\u003c/strong\u003e FUG09M134 control\u003c/p\u003e","description":"","filename":"FIG22.png","url":"https://assets-eu.researchsquare.com/files/rs-9032242/v1/4e2f290d43d6625891265701.png"},{"id":107637261,"identity":"b11dba99-d769-4c74-b2b9-39b3f8b85d51","added_by":"auto","created_at":"2026-04-23 12:41:53","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":9209693,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9032242/v1/46d21f97-db4e-4073-ab91-acb127f50a16.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Selection of antagonistic actinobacteria for Fusarium graminearum control","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe soil is a diverse environment and shelters an ecosystem, mainly composed of microorganisms. Bacteria, Archaea and Fungi play a fundamental role in soil maintenance, because it recycles organic matter through metabolic processes⁠. Actinomycetota stand out as one of the most prevalent phyla within the soil microbiota, frequently exhibiting high relative abundance in subterranean environments. They are responsible for the maintenance of soil\u0026rsquo;s carbon reserve and macronutrients through extracellular enzymes that play a fundamental role in organic matter degradation⁠\u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eActinobacteria belong to the Actinomycetota phylum, considered one of the biggest taxonomic units among bacteria. They are Gram-positive bacteria that contain high levels of guanine and cytosine (GC) in its genome\u003csup\u003e[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/sup\u003e⁠. They grow in a branched manner through the extension of their hyphae, forming mycelial structures and reproduce asexually through spores\u003csup\u003e[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e⁠. Its spore chains can present different conformations (short, long, spiral, etc.) and, through optical microscopy, these chains can be used for morphological identification.\u003c/p\u003e \u003cp\u003eActinobacteria are renowned for their prolific capacity to synthesize a diverse array of secondary metabolites and bioactive compounds of significant biotechnological value \u003csup\u003e[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e⁠, establishing them as a cornerstone of research across multiple applications. In the pharmaceutical industry, these secondary metabolites are indispensable, as the structural diversity of the substances produced encompasses a vast majority of clinically relevant antibiotics\u003csup\u003e[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/sup\u003e⁠. Furthermore, within the agricultural sector, their metabolic repertoire plays a critical role in modulating microbial ecosystems; specifically, Actinobacteria serve as potent biological control agents by suppressing the proliferation of various phytopathogens, thereby safeguarding plant health and enhancing crop productivity\u003csup\u003e[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eFungi of the genus \u003cem\u003eFusarium\u003c/em\u003e are members of the phylum Ascomycota, which has more than 1500 species. They can cause diseases in different types of crops such as onions, tomatoes, bananas, among others\u003csup\u003e[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/sup\u003e. A known way to deal with \u003cem\u003eFusarium\u003c/em\u003e contamination, as it is less harmful to the environment and human consumption, is the use of biological control agents\u003csup\u003e[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe aim of the present work is to select actinobacteria with the potential to be used as biological control agents against \u003cem\u003eFusarium graminearum\u003c/em\u003e.\u003c/p\u003e"},{"header":"Material and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eIsolates\u003c/h2\u003e \u003cp\u003eIn this work, 11 isolates of actinobacteria named as: Actinobacteria LMAF, LMA 1, LMA 2,LMA 3, LMA4, LMA 5, LMA 6,LMA 7,LMA 8,LMA, 9, LMA 10 (Table I) were tested against \u003cem\u003eFusarium graminearum\u003c/em\u003e isolates. The actinobacteria were isolated from soil of the Farroupilha park (located in the city of Porto Alegre, Rio Grande do Sul, Brazil) and belong to bacteria library of the Laborat\u0026oacute;rio de Microbiologia Aplicada at the Universidade Federal do Rio Grande do Sul (UFRGS).\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eMorphological characterization of Actinobacteria isolates\u003c/h3\u003e\n\u003cp\u003eThe morphological characterization of the actinobacteria colonies was carried out based on the International \u003cem\u003eStreptomyces\u003c/em\u003e Project\u003csup\u003e[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003e⁠ using the International \u003cem\u003eStreptomyces\u003c/em\u003e Project medium 2 (ISP2) (4 g yeast extract, 10 g malt extract, 4 g dextrose, 15 g agar, 1000 ml distilled water). Actinobacteria were streaked in Petri dishes with ISP2 medium and then incubated at 28\u0026ordm;C for 7 days. The following parameters were analyzed: the color of the colonies on the substrate, color of the spores in the aerial mycelium and edges of the isolated colonies. Images of the colonies were captured with a 50 megapixel camera.\u003c/p\u003e\n\u003ch3\u003eMicrostructure morphological characterization\u003c/h3\u003e\n\u003cp\u003eTo observe the microscopic structures of actinobacteria spore chains, microcultures were carried out in ISP2 and Starch Casein Agar (SCA) culture media (2 g KNO3, 2 g NaCl, 2 g K2HPO4, 0.05 mg MgSO4, 0.01 g FeSO4, 0.02 g CaCO3, 10 g starch, 0.3 g casein, 15 g agar, 1000 ml distilled water). The microculture plates were incubated at 28\u0026ordm;C for 7 days\u003csup\u003e[11\u0026acute;]\u003c/sup\u003e⁠. The morphology of the spore chains were evaluated for identification at genus level, according to \u003cem\u003eBergey's Manual of Determinative Bacteriology\u003c/em\u003e\u003csup\u003e[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]\u003c/sup\u003e⁠. The images were captured using a camera (MD90 - MShot) attached to the microscope.\u003c/p\u003e\n\u003ch3\u003eAntifungal assay\u003c/h3\u003e\n\u003cp\u003eActinobacteria samples were previously prepared in SCA culture medium. The fungi were previously incubated in Potato Dextrose Agar (PDA) culture medium (1000 ml distilled water; 140g potato broth; 15g Agar; 10g Dextrose). Two strains of \u003cem\u003eFusarium graminearum\u003c/em\u003e were used, named FUG4 and FUG09M134. To observe the antifungal activity of actinobacteria against de \u003cem\u003eFusarium\u003c/em\u003e strains, the plate confrontation method was used. For this purposes plates with PDA medium were inoculated at the center with a fungal agar plug, and at equidistant points (2.5cm) from the center four actinobacterial agar plugs were inoculated. The triplicate samples were incubated at 28\u0026ordm;C for 7 days, so that the fungal growth radius could be analyzed, according to Zou et al., (2021)⁠. The percentage of inhibition was calculated with the formula: Inhibition = [(C - T) / C] x 100, where C is the growth of the fungus in control, and T is the growth of the fungus in treatment.\u003c/p\u003e"},{"header":"Results and Discussion","content":"\u003cp\u003eThe morphological characterization of the eleven actinobacteria isolates was conducted by growing them in ISP2 medium. During this process, four different colors were observed in the aerial mycelia, three different colors for the colonies, and two types of edges were observed in all colonies (Table I). Actinobacteria belong to a very diverse group of bacteria is comprised most of soil microbiomes. It has been estimated that only 10% of the known actinobacteria have been isolated from soil. Many of these actinobacteria are found in rhizospheric soil, where they can be associated with plant roots and can provide protection against fungi and other microorganisms\u003csup\u003e[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/sup\u003e⁠. Actinobacteria have the ability to produce secondary metabolites and can be used as biological control agents. Therefore, they are a group of great importance for the agricultural field, as they can help to combat plant diseases\u003csup\u003e[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]\u003c/sup\u003e⁠. Due to the high diversity of these microorganisms, it is necessary to identify this group in order to achieve more accurate results.\u003c/p\u003e\n\u003cp\u003eRegarding the microstructure morphological characterization, according to the results obtained the actinobacteria isolate LMA 7 did not form spore chains; instead, fragmentation of the aerial mycelium was observed (Fig. \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec). Isolates LMA 2, LMA 3, and LMA 10 did not form enough spore chains for characterization through morphology of the spore chain. All other isolates were similar in terms of their shape and number of spores (Fig. \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ed), with small variations in the angle of the spiral. In this study, SCA was used as it is a less nutritious culture medium than ISP2, forming colonies more likely to produce spores and secondary metabolites. Microcultures carried out in SCA medium formed less fragmented and more abundant spore chains. Studies show that the morphology of the spore chain is a very important tool to identify actinobacteria\u003csup\u003e[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]\u003c/sup\u003e⁠. In addition, pigment production is an important characteristic of this group, and can be used to help identification\u003csup\u003e[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/sup\u003e, which is why the color of the colonies and the aerial mycelium were recorded.\u003c/p\u003e\n\u003cp\u003eAccording to \u003cem\u003eBergey\u0026apos;s Manual of Determinative Bacteriology\u003c/em\u003e, seven of eleven isolates are likely to belong to genus \u003cem\u003eStreptomyces\u003c/em\u003e, due to their morphological characteristics in microculture such as the formation of spirals in the spore chains. Given the results, a dominance in the occurrence of the genus \u003cem\u003eStreptomyces\u003c/em\u003e can be clearly observed. Among different types of habitat, soil is one of the best known for this genus, which has more than 850 species already described\u003csup\u003e[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/sup\u003e⁠. Due to its high diversity and abundance in the soil, the number of isolates belonging to this genus is expected to be high. Actinobacteria isolate LMA 7 was identified as \u003cem\u003eNocardia\u003c/em\u003e spp. (Table II) because in addition to not showing spore chains it presented fragmentation of the aerial mycelium. Recent studies showed that this genus is capable of producing antibiotics and can even be effective in controlling \u003cem\u003eCandida albicans\u003c/em\u003e\u003csup\u003e[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]\u003c/sup\u003e⁠.\u003c/p\u003e\n\u003cp\u003eFrom the eleven isolates tested against both \u003cem\u003eF. graminearum\u003c/em\u003e strains in the antifungal assay, one actinobacteria sample, LMAF, showed effectiveness in controlling the growth of both \u003cem\u003eF. graminearum\u003c/em\u003e. LMAF showed 33% with FUG4 \u003cstrong\u003e(\u003c/strong\u003eFig. \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea\u003cstrong\u003e)\u003c/strong\u003e and 40% of inhibition in the assay with FUG09M134 (Fig. \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed). Fungi of the genus \u003cem\u003eFusarium\u003c/em\u003e are known to cause \u003cem\u003eFusarium\u003c/em\u003e wilt, among other diseases, which leads to loss of productivity\u003csup\u003e[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/sup\u003e⁠. There are different ways to treat diseases caused by \u003cem\u003eFusarium\u003c/em\u003e, such as the use of post-grow copper to treat the disease\u003csup\u003e[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]\u003c/sup\u003e⁠, or pre-seeding treatments with essential oils to reduce the effects of the disease in the fully grown plant\u003csup\u003e[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]\u003c/sup\u003e⁠. A different way to control diseases caused by \u003cem\u003eFusarium\u003c/em\u003e is the use of biological control agents. In the study by Jing et al., (2020)⁠ the use of \u003cem\u003eStreptomyces\u003c/em\u003e isolates as biological control agents against banana wilt disease, caused by the fungus \u003cem\u003eFusarium oxysporum\u003c/em\u003e, was demonstrated.\u003c/p\u003e\n\u003cp\u003ePhenotypic and molecular identification of strain LMAF were previously established via MALDI-TOF MS and 16S rRNA gene analysis (using primers pA/pH and the Neighbor-Joining method in MEGA X), showing high similarity with \u003cem\u003eStreptomyces avidinii\u003c/em\u003e (accession number: PP410358) (Data not yet published). Biological control agents protect plants from diseases in different ways. Indirectly, they can induce resistance in plants or compete for space and nutrients with the pathogen. Directly, they can parasitize pathogens or produce antibiotics\u003csup\u003e[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]\u003c/sup\u003e⁠. According to the results, the interaction between the potential biological control agent and the pathogen is difficult to determine, since there may be the production of antibiotics or it may just be a competition for space and nutrients. In both possibilities there is interaction; therefore, biological control is plausible.\u003c/p\u003e\n\u003cp\u003eThe fungus \u003cem\u003eF. graminearum\u003c/em\u003e is part of a complex of species known to cause different types of diseases, such as fusariosis or blight, and affect different types of crops, such as corn, rice and wheat\u003csup\u003e[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]\u003c/sup\u003e⁠. The most common way to combat this fungus is the use of fungicides, but recent studies showed that there is a high occurrence of fungicide-resistant \u003cem\u003eF. graminearum\u003c/em\u003e \u003csup\u003e[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]\u003c/sup\u003e⁠. Taking into account the damage caused by \u003cem\u003eF. graminearum\u003c/em\u003e, and the great potential of actinobacteria to produce various compounds that can be useful in controlling fungal growth, it is necessary to identify new and different biological control agents, as well as the identification of actinobacteria that can perform this function. According to our results, isolate LMAF, previously identified as \u003cem\u003eStreptomyces avidinii\u003c/em\u003e, showed activity against the two \u003cem\u003eF. graminearum\u003c/em\u003e tested, which suggests a potential for use as a biological control agent. The use of species of this genus without a fully identification (species level) was shown in the work of⁠ Mattei et al. (2022), where spores of \u003cem\u003eStreptomyces\u003c/em\u003e sp. were used as biological control against \u003cem\u003eF. graminearum\u003c/em\u003e.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIsolate LMAF has the potential to be used as a biological control agent. The relationship between actinobacteria and fungi remains undetermined, and may be an indirect interaction, where the bacteria are simply competing for space and nutrients. It also can be direct, where there is production of substances that prevent the growth of fungi. More biochemical, genetic and chemical assays are necessary for more accurate identification of natural products and its production inducers. Thus, the isolate can go through new stages of testing to better evaluate its potential.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAcknowledgements\u003c/h2\u003e\n\u003cp\u003eThe authors acknowledge the Laboratory of Environmental Microbiology for providing the actinobacterial isolates and infrastructure support. CAPES e FAPERGS for financial support.\u003c/p\u003e\n\u003ch2\u003eFunding\u003c/h2\u003e\n\u003cp\u003eThis research was supported by CAPES and FAPERGS.\u003c/p\u003e\n\u003ch2\u003eConflicts of interest/Competing interests\u003c/h2\u003e\n\u003cp\u003eThe authors have no relevant financial or non-financial interests to disclose.\u003c/p\u003e\n\u003ch2\u003eEthics approval\u003c/h2\u003e\n\u003cp\u003eNot applicable. This study did not involve human participants or animals.\u003c/p\u003e\n\u003ch2\u003eConsent to participate\u003c/h2\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003ch2\u003eConsent for publication\u003c/h2\u003e\n\u003cp\u003eThe authors affirm that all participants provided informed consent for the publication of the data presented in this manuscript.\u003c/p\u003e\n\u003ch2\u003eAvailability of data and material\u003c/h2\u003e\n\u003cp\u003eThe datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003ch2\u003eCode availability\u003c/h2\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003ch2\u003eDeclaration of deposition in repositories\u003c/h2\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003ch2\u003eAuthors\u0026apos; contributions\u003c/h2\u003e\n\u003cp\u003eAll authors contributed to the study conception and design. Material preparation, data collection, and analysis were performed by all authors. The first draft of the manuscript was written by Yuri Borges V\u0026eacute;ras and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eZheng Q et al (2019) Soil multifunctionality is affected by the soil environment and by microbial community composition and diversity. Soil Biol Biochem 136:107521. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.soilbio.2019.107521\u003c/span\u003e\u003cspan address=\"10.1016/j.soilbio.2019.107521\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAraujo R et al (2020) Biogeography and emerging significance of Actinobacteria in Australia and Northern Antarctica soils. 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Microb Physiol 31:217\u0026ndash;232. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1159/000516864\u003c/span\u003e\u003cspan address=\"10.1159/000516864\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAbdullah A, Rahmawati R, Kurniatuhadi R, ANTIFUNGAL EXTRACT ACTIVITYOF (2020) ISOLATE Nocardia sp. ATS-4.1 AGAINST Candida albicans InaCC-Y116. Ber Biol 19. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.14203/beritabiologi.v19i3A.3868\u003c/span\u003e\u003cspan address=\"10.14203/beritabiologi.v19i3A.3868\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePoletto T, Muniz MFB, Fantinel VS, Harakava R, Rolim JM (2020) Characterization and Pathogenicity of Fusarium oxysporum Associated with Carya illinoinensis Seedlings. Floresta e Ambient 27. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1590/2179-8087.108917\u003c/span\u003e\u003cspan address=\"10.1590/2179-8087.108917\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLopez-Lima D, Mtz-Enriquez AI, Carri\u0026oacute;n G, Basurto-Cereceda S, Pariona N (2021) The bifunctional role of copper nanoparticles in tomato: Effective treatment for Fusarium wilt and plant growth promoter. Sci Hortic (Amsterdam) 277:109810. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.scienta.2020.109810\u003c/span\u003e\u003cspan address=\"10.1016/j.scienta.2020.109810\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGon\u0026ccedil;alves DC et al (2021) Reduction of Fusarium wilt symptoms in tomato seedlings following seed treatment with Origanum vulgare L. essential oil and carvacrol. Crop Prot 141:105487. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.cropro.2020.105487\u003c/span\u003e\u003cspan address=\"10.1016/j.cropro.2020.105487\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJing T et al (2020) Newly Isolated Streptomyces sp. JBS5-6 as a Potential Biocontrol Agent to Control Banana Fusarium Wilt: Genome Sequencing and Secondary Metabolite Cluster Profiles. Front Microbiol 11. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3389/fmicb.2020.602591\u003c/span\u003e\u003cspan address=\"10.3389/fmicb.2020.602591\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eK\u0026ouml;hl J, Kolnaar R, Ravensberg WJ (2019) Mode of Action of Microbial Biological Control Agents Against Plant Diseases: Relevance Beyond Efficacy. Front Plant Sci 10. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3389/fpls.2019.00845\u003c/span\u003e\u003cspan address=\"10.3389/fpls.2019.00845\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDel Ponte EM et al (2022) Fusarium graminearum Species Complex: A Bibliographic Analysis and Web-Accessible Database for Global Mapping of Species and Trichothecene Toxin Chemotypes. \u003cem\u003ePhytopathology\u0026reg;\u003c/em\u003e 112, 741\u0026ndash;751 \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1094/PHYTO-06-21-0277-RVW\u003c/span\u003e\u003cspan address=\"10.1094/PHYTO-06-21-0277-RVW\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ede Chaves MA et al (2022) Fungicide Resistance in Fusarium graminearum Species Complex. Curr Microbiol 79:62. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00284-021-02759-4\u003c/span\u003e\u003cspan address=\"10.1007/s00284-021-02759-4\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMattei V et al (2022) Wheat Seed Coating with Streptomyces sp. Strain DEF39 Spores Protects against Fusarium Head Blight. Microorganisms 10:1536. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/microorganisms10081536\u003c/span\u003e\u003cspan address=\"10.3390/microorganisms10081536\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Tables","content":" \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Taba\" border=\"1\"\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003eTable I Colony Morphology\u003c/div\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eIsolate\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eAerial mycelium color\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eColony color\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eEdge\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eLMAF\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003eYellow\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003eYellow\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cdiv class=\"SimplePara\"\u003eIrregular\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eLMA 1\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003eYellow\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003eYellow\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cdiv class=\"SimplePara\"\u003eIrregular\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eLMA 2\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003eWhite\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003eYellow\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cdiv class=\"SimplePara\"\u003eRound\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eLMA 3\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003eYellow\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003eYellow\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cdiv class=\"SimplePara\"\u003eIrregular\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eLMA 4\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003eWhite\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003eYellow\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cdiv class=\"SimplePara\"\u003eRound\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eLMA 5\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003eWhite\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003eBrown\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cdiv class=\"SimplePara\"\u003eRound\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eLMA 6\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003eLight Brown\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003eDark Brown\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cdiv class=\"SimplePara\"\u003eIrregular\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eLMA 7\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003eWhite\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003eYellow\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cdiv class=\"SimplePara\"\u003eRound\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eLMA 8\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003eWhite\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003eYellow\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cdiv class=\"SimplePara\"\u003eIrregular\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eLMA 9\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003eGrey\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003eYellow\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cdiv class=\"SimplePara\"\u003eRound\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eLMA 10\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003eYellow\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003eYellow\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cdiv class=\"SimplePara\"\u003eIrregular\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003cbr/\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Tabb\" border=\"1\"\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003eTable II Spore chain morphological identification\u003c/div\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eIsolate\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eSpore chain\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eGenus\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eLMAF\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003eSpira\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Italic\" class=\"Italic\" name=\"Emphasis\"\u003eStreptomyces\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eLMA 1\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003eSpira\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Italic\" class=\"Italic\" name=\"Emphasis\"\u003eStreptomyces\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eLMA 2\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003e-\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003eW/I\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eLMA 3\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003e-\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003eW/I\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eLMA 4\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003eSpira\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Italic\" class=\"Italic\" name=\"Emphasis\"\u003eStreptomyces\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eLMA 5\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003eSpira\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Italic\" class=\"Italic\" name=\"Emphasis\"\u003eStreptomyces\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eLMA 6\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003eSpira\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Italic\" class=\"Italic\" name=\"Emphasis\"\u003eStreptomyces\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eLMA 7\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003eFragmented mycelium\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Italic\" class=\"Italic\" name=\"Emphasis\"\u003eNocardia\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eLMA 8\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003eSpira\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Italic\" class=\"Italic\" name=\"Emphasis\"\u003eStreptomyces\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eLMA 9\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003eSpira\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Italic\" class=\"Italic\" name=\"Emphasis\"\u003eStreptomyces\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eLMA 10\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003e-\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003eW/I\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"3\"\u003eW/I: Without identification\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003cbr/\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":false,"email":"","identity":"current-microbiology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"","title":"Current Microbiology","twitterHandle":"","acdcEnabled":false,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"VoR Journals","inReviewEnabled":false,"inReviewRevisionsEnabled":false},"keywords":"Actinobacteria, Biological Control, Morphological identification, Phytopathogenic fungi, Antifungal activity","lastPublishedDoi":"10.21203/rs.3.rs-9032242/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9032242/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eFungi of the genus \u003cem\u003eFusarium\u003c/em\u003e cause damage in different types of crops such as tomatoes, onions, bananas, among others, causing different diseases such as wilt disease or \u003cem\u003eFusarium\u003c/em\u003e Head Blight (FHB). Recent studies show that \u003cem\u003eFusarium graminearum\u003c/em\u003e has a high resistance to fungicide and alternative treatment needs to be searched. There are different ways to treat diseases caused by \u003cem\u003eFusarium\u003c/em\u003e, between them, the most relevant is the use of biological control agents. The use of actinobacteria as a biological control agent is considered promising, due to the fact that the most important and known characteristic of this bacteria is the production of secondary metabolites and bioactive compounds. In the present study, eleven actinobacteria isolates were identified by morphological characteristics and submitted to antifungal assay against two isolates of \u003cem\u003eFusarium graminearum\u003c/em\u003e. As a result of the preliminary identification one isolate was identified as \u003cem\u003eNocardia spp.\u003c/em\u003e, seven isolates as \u003cem\u003eStreptomyces spp.\u003c/em\u003e and three remained unidentified morphologically. The antagonistic assay was performed using the plate confrontation method, against the two strains of \u003cem\u003eFusarium graminearum\u003c/em\u003e. The isolate LMAF, previously identified as \u003cem\u003eStreptomyces avidinii\u003c/em\u003e, showed activity against both \u003cem\u003eFusarium graminearum\u003c/em\u003e isolates. The relation between the pathogen and the \u003cem\u003eStreptomyces avidinii\u003c/em\u003e LMAF remain unsure, due to the fact that it can be direct, where the isolate is producing substances that control the growth, or indirect, where both are competing for nutrients and space. Both cases lead to the potential use of isolate LMAF as a biological control agent.\u003c/p\u003e","manuscriptTitle":"Selection of antagonistic actinobacteria for Fusarium graminearum control","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-23 12:40:36","doi":"10.21203/rs.3.rs-9032242/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2026-05-17T14:48:37+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-05T13:35:11+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"142629173431550142133708619212853732139","date":"2026-05-04T15:15:25+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-04T06:39:00+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"39871846232451324259927084193299426204","date":"2026-04-30T11:42:50+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"241176526821472515832883202125748511081","date":"2026-04-29T15:26:02+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-04-16T05:06:29+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-08T14:06:41+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-03-06T06:40:00+00:00","index":"","fulltext":""},{"type":"submitted","content":"Current Microbiology","date":"2026-03-04T15:56:02+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":false,"email":"","identity":"current-microbiology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"","title":"Current Microbiology","twitterHandle":"","acdcEnabled":false,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"VoR Journals","inReviewEnabled":false,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"72dd2697-5234-4dc0-afda-bd37a66cbd9a","owner":[],"postedDate":"April 23rd, 2026","published":true,"recentEditorialEvents":[{"type":"editorInvitedReview","content":"","date":"2026-05-17T14:48:37+00:00","index":47,"fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-05T13:35:11+00:00","index":46,"fulltext":""},{"type":"reviewerAgreed","content":"142629173431550142133708619212853732139","date":"2026-05-04T15:15:25+00:00","index":45,"fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-04T06:39:00+00:00","index":44,"fulltext":""},{"type":"reviewerAgreed","content":"39871846232451324259927084193299426204","date":"2026-04-30T11:42:50+00:00","index":41,"fulltext":""},{"type":"reviewerAgreed","content":"241176526821472515832883202125748511081","date":"2026-04-29T15:26:02+00:00","index":40,"fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-04-23T12:40:41+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-23 12:40:36","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9032242","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9032242","identity":"rs-9032242","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}