Identification and characterization of siderophilic biocontrol strain SL-44 combined with whole genome.

Using rhizobacteria as biological fertilizer is gradually expanding in agriculture as excellent substitutes for chemical fertilizers. Bacillus subtilis SL-44 is a plant growth-promoting rhizobacteria screened from the severely salinized cotton rhizosphere soil in Xinjiang. Study showed that indole-3-acetic acid, organic acid production, nitrogen fixation, and other beneficial secondary metabolite secretion can be synthesized by stain SL-44. At the same time, fencyclin, lipopeptide, chitinase, and other antifungal substances were also detected from the secretion of Bacillus subtilis SL-44, which can effectively control plant diseases. Siderophore separated from SL-44 was verified by HPLC, and results showed it was likely bacillibactin. This study also verified that SL-44 has high antifungal activity against Rhizoctonia solani through in vitro antifungal experiments. The B. subtilis SL-44 whole genome was sequenced and annotated to further explore the biotechnological potential of SL-44. And a large number of genes involved in the synthesis of anti-oxidative stress, antibiotic, and toxins were found. Genome-wide analysis provides clear evidence to support the great potential of B. subtilis SL-44 strain to produce multiple bioantagonistic natural products and growth-promoting metabolites, which may facilitate further research into effective therapies for harmful diseases.