Microbiological and Biosecurity Assessment of Sargassum‐Based Liquid Biofertilizers

Sargassum seaweed has inundated Caribbean coastlines, disrupting ecosystems while presenting opportunities for sustainable products like liquid biofertilizers. This study evaluated the microbiological and biosecurity profiles of two liquid biofertilizers produced in the Dominican Republic: Sargassum-based (SBLB-INTEC) and conventional (LB-BANELINO). Both exhibited essential minerals (K, Ca, Mg) and low heavy metal concentrations, meeting agricultural safety standards. Metagenomic analysis (16S rRNA) identified diverse bacterial and archaeal communities, mainly consisting of beneficial taxa such as Firmicutes, Proteobacteria, and Methanobacteria, with no detectable pathogens. Ecotoxicological assays with Lactuca sativa showed phytotoxicity at high concentrations, mitigated by dilution (≤6.25%) and pH adjustment (7.0), achieving germination indexes above 80%. These results suggest that Sargassum-based biofertilizers could be a viable alternative for enhancing soil fertility and promoting sustainable crop production, particularly in coastal agricultural systems where conventional fertilizers may be limited or environmentally harmful. Moreover, this study highlights the critical role of ecotoxicological testing in ensuring biofertilizer safety and underscores Sargassum’s potential as a renewable resource for sustainable farming.