Biocontrol activity of surfactin A purified from Bacillus NH-100 and NH-217 against rice bakanae disease

Abstract

The potential of the Bacillus genus to antagonize phytopathogens is associated with the production of cyclic lipopeptides. Depending upon the type of lipopeptide, they may serve as biocontrol agents that are eco-friendly alternatives to chemical fertilizers. This study evaluates the biocontrol activity of surfactin-producing Bacillus (SPB) strains NH-100 and NH-217 and purified surfactin A from these strains against rice bakanae disease. Biologically active surfactin fractions were purified by HPLC, and surfactin A variants with chain lengths from C12 to C16 were confirmed by LCMS-ESI. In hemolytic assays, a positive correlation between surfactin A production and halo zone formation was observed. The purified surfactin A had strong antifungal activity against Fusarium oxysporum, F. moniliforme, F. solani, Trichoderma atroviride and T. reesei. Maximum fungal growth suppression (84%) was recorded at 2000 ppm against F. moniliforme. Surfactin A retained antifungal activity at different pH levels (5-9) and temperatures (20, 50 and 121 °C). Hydroponic and pot experiments were conducted to determine the biocontrol activity of SPB strains and the purified surfactin A from these strains on Super Basmati rice. Surfactin production in the rice rhizosphere was detected by LCMS-ESI at early growth stages in hydroponics experiments inoculated with SPB strains. However, the maximum yield was observed with a consortium of SPB strains (T4) and purified surfactin A (T5) treatments in the pot experiment. The outcomes of the present study revealed that surfactin A significantly reduced rice bakanae disease by up to 80%. These findings suggest that purified surfactin A could be an effective biocontrol agent against bakanae disease in rice and should be incorporated into strategies for disease management.

Antibacterial activity against Ralstonia solanacearum of the lipopeptides secreted from the Bacillus amyloliquefaciens strain FJAT ‐2349

“…Sarwar et al . () found that surfactin A purified from the Bacillus strains NH‐100 and NH‐217 could significantly reduce rice bakanae disease by up to 80%. We further demonstrated that the LP mixtures from B. amyloliquefaciens strain FJAT‐2349 had a biocontrol efficacy of 97·6% against tomato bacterial wilt when 100% of tomato seedlings in the control treatment suffered from damping‐off.…”

“…Biocontrol is an alternative method to resolve some of the above difficulties (Aino 2016). Many studies have indicated that the LPs produced from Bacillus species can potentially be developed as biocontrol agents against plant diseases (Mejri et al 2018;Sarwar et al 2018). In this work, the authors found that the LP extracts produced by B. amyloliquefaciens strain FJAT-2349 could effectively inhibit the growth of R. solanacearum in vitro.…”

“…; Sarwar et al . ). In this work, the authors found that the LP extracts produced by B. amyloliquefaciens strain FJAT‐2349 could effectively inhibit the growth of R. solanacearum in vitro .…”

“…It is now widely recognized that LPs play a major role in plant disease suppression (Ramyabharathi and Raguchander 2014). Due to these beneficial traits, LPs can be potentially useful as biocontrol agents against plant diseases (Mejri et al 2018;Sarwar et al 2018).…”

Halotolerant bacteria belonging to operational group Bacillus amyloliquefaciens in biocontrol of the rice brown stripe pathogen Acidovorax oryzae

“…; Sarwar et al . ). Interestingly, MALDI‐TOF MS data in this study showed that the two antagonistic isolates were able to produce variety of cyclic lipopeptides (CLPs) including surfactins, iturins, bacilliomycin (iturin family) and fengycin.…”