Lipopeptide mediated biocontrol activity of endophytic Bacillus subtilis against fungal phytopathogens

Abstract

Background The use of chemical fungicides against fungal pathogens adversely affects soil and plant health thereby resulting in overall environmental hazards. Therefore, biological source for obtaining antifungal agents is considered as an environment-friendly alternative for controlling fungal pathogens. Results In this study, seven endophytic bacteria were isolated from sugarcane leaves and screened for its antifungal activity against 10 fungal isolates belonging to the genera Alternaria, Cochliobolus, Curvularia, Fusarium, Neodeightonia, Phomopsis and Saccharicola isolated from diseased leaves of sugarcane. Among the seven bacterial isolates, SCB-1 showed potent antagonistic activity against the tested fungi. Based on the phenotypic data, Fatty Acid Methyl Esters (FAME) and 16S rRNA gene sequence analysis, the isolate SCB-1 was identified as Bacillus subtilis . The bacterial isolate was screened negative for chitinase production; however, chloroform and methanol extracts of the bacterial culture caused significant inhibition in the growth of the fungal isolates on semisolid media. Volatile component assay showed highest inhibitory activity against Saccharicola bicolor (SC1.4). A PCR based study detected the presence of the genes involved in biosynthesis of surfactin, bacillaene, difficidin, macrolactins and fengycin. Mass spectrometric analysis of the bacterial extract detected the presence of antifungal lipopeptide surfactin, but other metabolites were not detected. The biocontrol activity of the bacterial isolate was established when bacterial pretreated mung bean seeds were able to resist Fusarium infection, however, the untreated seeds failed to germinate. Conclusion The antifungal potential of isolate Bacillus subtilis SCB-1 was established against taxonomically diverse fungal pathogens including the genera Saccharicola , Cochliobolus, Alternaria and Fusarium . The potent antifungal compound surfactin as well as volatiles produced by the bacterial isolate could be responsible for its bio-control activity against fungal infections. Electronic supplementary material The online version of this article (10.1186/s12866-019-1440-8) contains supplementary material, which is available to authorized users.

Plant growth promoting and antifungal activity in endophytic Bacillus strains from pearl millet (Pennisetum glaucum)

“…PCR based screening of AMP gene(s) in the present study clearly reflected the presence srfA, bmyC, and ituD genes in all the endophytic Bacillus strains. These results are in line with other researchers that correlated presence of multiple antifungal peptide genes with antagonistic capabilities of Bacillus strains [20,22,25,26,43,71]. Thus, these AMP genes and their secretions by antagonists act as one of the vital components for effective pathogen inhibition.…”

Seed‐borne endophytic Bacillus velezensis LHSB1 mediate the biocontrol of peanut stem rot caused by Sclerotium rolfsii

“…Plant endophytes are reported to suppress plant pathogens and protect plants by multiple mechanisms, for example, antibiosis by producing various antimicrobial metabolites (Backman and Sikora ; Chen et al ). Among these reported metabolites, Bacillus lipopeptides were considered as versatile weapons for plant disease biocontrol, acting as ‘antagonists’ to inhibit the growth of many phytopathogens through their membrane permeabilization, disruption or solubilization (Ongena and Jacques ; Hazarika et al ). Many research have reported the excellent antibiosis of Bacillus lipopeptides, for example, B. amyloliquefaciens PGPBacCA1 was shown to be able to coproduce the lipopeptides surfactin, iturin and fengycin, which were responsible for the effective antifungal effects against S. rolfsii , Sclerotinia sclerotiorum and F. solani (Torres et al ), while surfactin was proved to be responsible for the biocontrol activity of B. subtilis SCB‐1 against diverse fungi including the genera Saccharicola , Cochliobolus , Alternaria and Fusarium (Hazarika et al ).…”

Lesson from Ecotoxicity: Revisiting the Microbial Lipopeptides for the Management of Emerging Diseases for Crop Protection

“…Shafi et al [201] advocated that the Bacillus species has numbers of antagonizing attributes against plant pathogens including the production of lipopeptides, enzymes, and plant growth promotion. Hazarika et al [202] studied the role of lipopeptides produced by leaf endophytes against 10fungal species.…”