Biosurfactant production by a CO2 sequestering Bacillus sp. strain ISTS2

A chemolithotrophic bacterium, Bacillus sp. strain ISTS2, produced biosurfactant when enriched in the chemostat in presence of sodium bicarbonate as carbon source was evaluated for carbon dioxide (CO2) sequestration and biosurfactant production. CO2 sequestration efficiency of the bacterium was determined by enzymatic activity of carbonic anhydrase and ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO). Biosurfactant production ability at 100 mM NHCO3 and 5% CO2 was screened by surface and interfacial tension measurement, emulsification stability test, hydrophobicity test, contact angle measurement, bacterial adhesion to hydrocarbon and purified by silica gel column (60-120 mesh). Thin layer chromatography (TLC) and gas chromatography-mass spectrometry (GC-MS) showed that the crude biosurfactant of ISTS2 were composed of lipopeptides and free fatty acids (FA) and its hydrophobic fraction contained five kinds of fatty acids (FA) with chain lengths of C14-C19. Thus Bacillus sp. strain IST2 can be used as a cleaner bioprocess for the utilization of industrial CO2 as alternate substrate.