A Gram-positive bacterium was isolated from mangrove soil and was identified as Bacillus licheniformis (KC710973). The potential of a mangrove microorganism to utilize different natural waste carbon substrates for biosurfactant production and biodegradation of hydrocarbons was evaluated. Among several substrates used in the present study, orange peel was found to be best substrate of biosurfactant yield with 1.796 g/L and emulsification activity of 75.17 % against diesel. Fourier transform infrared spectroscopy analysis of biosurfactant compound revealed that the isolated biosurfactant is in lipopeptide nature. The 1H-NMR of the extracted biosurfactant from B. licheniformis has a doublet signal at 0.8-0.9 ppm corresponding to six hydrogen atoms suggests the presence of a terminal isopropyl group. The spectra showed two main regions corresponding to resonance of α-carbon protons (3.5-5.5 ppm) and side-chain protons (0.25-3.0 ppm). All the data suggests that the fatty acid residue is from lipopeptide. From the biodegradation studies, it concluded that the biosurfactant produced by B. licheniformis further can add to its value as an ecofriendly and biodegradable product.
Keywords: Bacillus licheniformis; Emulsification activity; Lipopeptide; NMR analysis; Orange peels.