Development of a Plant Growth Promoting Bacterial EcoBiome Derived from Desert Soil Isolates

Abstract The application of plant growth-promoting (PGP) bacteria is increasingly studied for its potential to improve plant tolerance to biotic and abiotic stress. Developing synthetic microbial consortia represents a promising strategy, as it can enhance colonization success and functional synergy within the rhizosphere. In this study, we designed a stable EcoBiome derived from a synthetic community (SynCom) of 17 bacterial isolates obtained from three desert environments. We evaluated their PGP traits, including siderophore production, indoleacetic acid (IAA) synthesis, phosphate solubilization, and nitrogen fixation. Using Oxford Nanopore Technologies (ONT) sequencing of 16S rRNA genes, we tracked changes in relative abundance across successive subcultures under four temperature conditions. From this analysis, Erwinia rhapontici 1SR, Pseudomonas yamanorum RZ5, and Plantibacter sp. RU18 were identified as the dominant isolates and subsequently selected to construct the EcoBiome. Functional characterization showed that these isolates exhibited complementary PGP traits, biofilm formation capacity, and tolerance to water stress, both individually and in combinations. These findings highlight the potential of desert- derived bacterial consortia as microbial resources for developing biostimulants to enhance plant resilience under environmental stress conditions. Importance Several studies have focused on obtaining bacterial isolates with plant growth promoting traits, however, their success as microbial inoculants with plant stimulant activity is diminished (or null) because they do not have the ability to compete efficiently with the natural soil microbiome. Thus, in this study we designed a synthetic community of 17 bacteria from desert environments and individually characterized their plant growth-promoting attributes, and in parallel we subjected this synthetic community to co-culture, subsequently evaluating its temporal prevalence (24 and 48 hours of culture) and at four different temperatures. With this, we developed and presented a stable EcoBiome of three isolates (one from each desert), stable over time, with attributes that promote plant growth and proliferation in hostile conditions, such as drought, with the purpose of being used as microbial inoculants as a whole, capable of competing, proliferating and forming part of the rhizosphere microbiome.