Production, characterization and biotechnological potential of lipopeptide biosurfactants from a novel marine Bacillus stratosphericus strain FLU5

Abstract

This work aimed to study the potential of a newly marine bacterium, Bacillus stratosphericus FLU5, to produce an efficient surface active agent BS-FLU5. Biosurfactant production was examined on different carbon sources using the surface tension measurement and the oil displacement test. Strain FLU5 showed its capacity to produce biosurfactants on the most of tested substrates and in particular the residual frying oil, which is an alternative, cheap and renewable carbon source, thus minimizing the high cost of producing surfactants. MALDI-TOF MS/MS analyses confirmed the presence of lipopeptides identified as members of surfactin and pumilacidin isomers. The critical micellar concentration of the purified lipopeptides produced by strain FLU5 was 50 mg/l and, at this concentration, the surface tension of the water was reduced from 72 to 28 mN/m. Furthermore, the crude lipopeptides showed interest stability against a broad range of pH (2.1-12), temperature (10-121 °C) and salinity (0-120 g/l NaCl). The biosurfactant BS-FLU5 demonstrated negligible cytotoxic effect against mammalian cells (HEK293 human embryonic kidney cell line) at all of tested concentration (125-1000 µg/ml). The application of BS-FLU5 in oil recovery from soil contaminated by hydrocarbons ( used motor oil) showed that it was more effective on the hydrocarbon-remobilization than some tested synthetic surfactants. These results highlight the applicability of the lipopeptides produced by the new marine Bacillus stratosphericus strain FLU5 in different fields, especially in environmental remediation processes. Production of lipopeptides is a characteristic of several Bacillus species, but to the best of our knowledge, this is the first report showing the potential of Bacillus stratosphericus for efficient production of biosurfactants or lipopeptides.