Production of Lipopeptide Biosurfactant Using Wastewater from Parboiled Paddy Rice and Evaluation of Antifungal Property of the Biosurfactant Against Two Dermatophyte Fungi.

Abstract

A previously isolated lipopeptide biosurfactant-producing bacterium Bacillus licheniformis SCV1 was investigated for the production of the biosurfactant using wastewater from parboiled paddy rice. The biosurfactant thus produced was evaluated for its antifungal property against dermatophyte fungi Trichophyton ajelloi and Microsporum fulvum. Results revealed that the bacterial strain reduced surface tension of the media from 56.16 ± 1 mN/m to 35 ± 0.9 mN/m within 12 h, which further shrank to 29.3 ± 1 mN/m in 24 h of incubation. The yield of the biosurfactant was 3.15 ± 0.25 g/L at 48 h of incubation. The obtained biosurfactant exhibited efficient emulsifying activity against a wide range of hydrophobic substrates such as crude oil, olive oil, engine oil, and kerosene oil used in the study. The critical micelle concentration of the biosurfactant was found to be 80 mg/L. Structural characterization using FT-IR and TLC revealed that the biosurfactant produced by the strain in the wastewater is a lipopeptide consisting of surfactin and iturin. LCMS analysis revealed that the surfactin homologs range from C12 to C17-surfactin while the iturin contains C13 to C17-iturin homologs. It also revealed an in vitro study that the biosurfactant has antifungal properties against dermatophyte fungi Trichophyton ajelloi and Microsporum fulvum. Microscopic observation of the hyphae of the treated dermatophyte revealed disruption and fissure of the mycelia. The chemical composition of the wastewater revealed that it contains adequate nutritional composition and micronutrients to support bacterial growth. This is the first report that the wastewater of parboiled paddy could be used as a low-cost substrate for the production of lipopeptide biosurfactant, and the biosurfactant could be used for preventing dermatophytes fungi.