Antifungal Activity and Presence of Lipopeptides Genes in Bacillus subtilis Isolated from the Rhizosphere of Pluchea sericea

Abstract

Cotton production in the Mexicali valley is adversely affected by wilt and root rot disease associated with Fusarium species. Therefore, the aim of this study was to identify the antifungal activity and presence of lipopeptides genes in Bacillus subtilis strain Bs-Cach isolated from the rhizosphere of the cachanilla (Pluchea sericea). The dual culture technique was conducted to test antifungal effect of the Bs-Cach on the growth of Fusarium solani strains (ICA-3 and ICA-4, respectively), and the presence of iturin (ItuA), surfactin (SrfC), and fengycin (FenD) (lipopeptides genes), was evaluated by PCR analysis. The results obtained revealed that Bs-Cach inhibited the growth of F. solani ICA-3 and ICA-4, with a range of percentage inhibition from 50 and 52 after 120 h, respectively. On the other hand, our result of the PCR amplification of the lipopeptide genes from DNA of Bs-Cach showed solely the presence of iturin but not surfactin and fengycin genes. The analysis of sequence ituA present in Bs-Cach showed 84 % identity with iturin A synthetase of different B. subtilis strains. This study showed that B. subtilis Bs-Cach strain has the ability of inhibiting F. solani strains by at least one mechanism, the lipopeptide synthesis. This result turns Bs-Cach into a potential alternative for the biological control of F. solani. Nevertheless, this study was conducted under in vitro conditions, and further studies are required to investigate whether these results hold true under field conditions.