Genome sequencing and functional annotation of Bacillus sp. strain BS-Z15 isolated from cotton rhizosphere soil having antagonistic activity against Verticillium dahliae.

In the present study, antagonistic activity of bacterial strain BS-Z15, was evaluated against Verticillium dahlia. The fermented broth of BS-Z15 inhibited the growth of Verticillium dahliae. The genome of strain BS-Z15 had a total size of 4,068,702 base pairs and contained 4318 genes, of which 4196 are coding sequences and 122 are non-coding RNA. Among these genes, nine genomic islands, 86 tRNAs, 13 sRNAs, and one prophage was determined. With the help of annotation databases, most unigene functions were identified. At the same time, genomic comparison between BS-Z15 and 12 Bacillus members showed that the genes of BS-Z15 were closely related to the Bacillus group, and were conserved between the two groups, including most of the genes associated with fungal antagonism. BS-Z15 contains genes involved in a variety of antagonistic mechanisms, including genes encoding or synthesizing mycosubtilin, chitinases (but not CHIA and CHIB), glycoside hydrolases, iron nutrients, and antibiosis. However, it only contained the complete mycosubtilin- and bacilibactin-related operators in the reported main antifungal gene cluster of B. subtilis. Mycosubtilin and bacilibactin may be the main active antifungal substance. Besides, some genes could encode products related to biofilm production, which may be related to the colonization ability of the strain in plant rhizospheres. The complete genome of B. subtilis BS-Z15 provided new insights into the potential metabolites it produces related to its biocontrol activity.