Biosurfactants from Bacillus sp A5F as biocontrol agent for soybean crop

Abstract

Bacillus sp. A5F possesses the potential to produce biosurfactants under in-vitro conditions. Glucose, soybean oil, and incubation time were identified as significant variables affecting the production of biosurfactants. The selected ingredients were optimized using response surface methodology that resulted in 2.14-folds enhancement in biosurfactant levels in 5 l fermentor. Optimal values of culture variables obtained are 3.5 g l-1, 3.5 ml l-1, and 78 h for glucose, soybean oil, and incubation time, respectively. Purified fraction were subjected to LCMS/MS and LC QToF-MS analysis revealed iturin and surfactin type biosurfactant along with other small lipopeptides with antimicrobial activity. Biosurfactant was found active against potent soybean phytopathogens and causes lysis of cell membrane. 600 µg ml-1 of biosurfactants significantly reduced disease incidence of S. sclerotiorum in soybean plants and treated leaves were found to be asymptomatic. Real time PCR quantification of microbial abundance suggests that ITS gene copy number reduce by 12 % due to biosurfactant spray on leaves and less non target effect on resident eubacterial population. newline