Promising abilities of mercapto-degrading Staphylococcus capitis strain SH6 in both crude oil and waste motor oil as sole carbon and energy sources: its biosurfactant production and preliminary characterization

BACKGROUND: It was shown previously that a Staphylococcus capitis strain SH6 was able to degrade several malodorous mercaptans and simultaneously reduce the surface tension. RESULTS: This present work revealed the capacity of strain SH6 to grow on various hydrocarbons, used as the only carbon and energy sources. Based on GC–MS analyses, the substantial ability to degrade up to 45% and 64% of aliphatic hydrocarbons (n-alkanes) of crude oil and waste motor oil, respectively, after 30 days of incubation at 37 °C and 180 rpm, was shown. The properties of biosurfactant produced by strain SH6 grown on different oil substrates (diesel oil and waste motor oil) were studied. Biosurfactants exhibited enhanced emulsification capacities and significant stabilities over a wide range of salinity (20–150 g L-1), temperature (–20–100 °C), and pH, and also the ability to remove crude oil from contaminated soils. Their critical micelle concentrations (CMC) were of 800 mg L-1. FTIR analyses suggested the lipopetide nature of biosurfactants. CONCLUSION: The stabilities of biosurfactants over a wide pH range, high temperatures and variable concentrations of salt, as well as emulsifying properties, suggest potential applications in bioremediation processes. © 2017 Society of Chemical Industry.