Biosurfactant production by Alcaligenes sp. using agro-industrial wastes.

Biosurfactants are amphipathic, surface-active, nontoxic, and biodegradable compounds with wide applications in different industrial preparations. The present study was carried out to identify the biosurfactant-producing bacterial strains and surfactant production optimization with agro-industrial wastes. The potential biosurfactant-producing bacterial strain SS-1 was isolated from industrial effluent, and its surfactant-producing capabilities were determined via drop collapse assay, emulsification index, and reduction in surface tension. 16 S rRNA gene sequencing revealed 99% homology of isolate SS-1 with Alcaligenes sp. Agro-industrial wastes, namely, molasses, whey, and rapeseed cake, were optimized for biosurfactant production by the SS-1 strain, and maximum production was reported with molasses (4%). The present research has also documented an emulsification index of 93.26 ± 0.76% and surface tension reduction up to 35.26 ± 0.70 mN/m with an overall yield of biosurfactant approximately 2.38 g/L using 4% molasses at pH 7 and a temperature of 36 °C by Alcaligenes sp. FT-IR analysis revealed the presence of various functional groups, including O-H, N-H, C = O, C-H, and C-O-C, which suggest the lipopeptide nature of the biosurfactant. This was further validated by the distinctive resonance peaks observed in the NMR spectrum. The molecular mass of the biosurfactant was deduced to be 1382 Da via LC-MS. The partially purified biosurfactant was stable over a wide range of temperatures and pH values, with a maximum emulsification at pH 7 and a temperature of 30 °C. [ABSTRACT FROM AUTHOR]