Surfactin-Like Biosurfactant Production and Optimization by Bacillus Subtilis SNW3: Product Characterization and Its Influence on Seed Development and Plant Growth

Abstract Background: Biosurfactants, being environment friendly, highly biodegradable, less toxic and stable compounds have applications in several environmental and industrial sectors that includes cosmetics, biomedical, bioremediation, and agriculture. Growing concern about eco-friendly compounds leads to replacement of chemical surfactants with biological surfactants. However, use of biosurfactant limits due to high production cost. Surfactin, a class of lipopeptide, considered as powerful biosurfactants having wide applications in therapeutics and environmental field. This study aims to investigate production and characterization of surfactin by Bacillus subtilis SNW3 and evaluating their potential application in seed germination and plant growth. Results: In present study, Bacillus subtilis SNW3 was previously isolated from Chakwal Pakistan and used for biosurfactant production. Optimized media for biosurfactant production was at (6% w/v) white beans powder in combination with (1.5% w/v) waste frying oil and (0.1% w/v) urea that shows surface tension reduction (28.8 mN/m), oil displacement assay (4.9 cm) and emulsification index (69.8 %). Environmental growth parameters like temperature (30 °C), inoculum size (1%), pH (6) and agitation (150 rpm) exhibit important role towards enhanced biosurfactant yield. Furthermore, surfactin obtained was found to be most stable at (5-7) pH, (8%) NaCl and (100 °C) temperature. Biosurfactant obtained was of lipopeptide nature called surfactin characterized by thin-layer chromatography (TLC) and fourier-transform infrared spectroscopy (FTIR). The surfactin obtained, used in a concentration of (0.7 g/100 mL) helps in seed germination and significantly enhanced growth of Solanum lycopersicum (tomato), Pisum sativum (pea), Capsicum annuum (peppers) and Lactuca sativa (lettuce).Conclusions: Bacillus subtilis SNW3 produces surfactin with more stability, that makes it useful for processing of food and in agriculture. The use of white beans powder and waste frying oil as sole source of carbon and energy makes the biosurfactant production more profitable, and environment friendly procedure by utilizing food processing by-products and wastes as substrate. Results obtained provide understanding about surfactin use for seed development and plant growth.