Study on Biosurfactant Production by Two Bacillus Species

With increasing demand of biosurfactants for environmental and industrial application, there is increased interest in prospecting of microorganisms and substrates for production of substantial quantities of biosurfactants. A study was carried out to investigate the ability of Bacillus sphaericus EN3 and Bacillus azotoformans EN16 to produce large quantities of biosurfactants and determine a suitable substrate for its production. The organisms were previously screened for biosurfactant production and found to be good candidates. Three carbon sources including glucose, diesel and crude oil were used and incorporated into modified Bushnell - Haas medium at 2% w/v concentration. Large quantities of biosurfactants were observed when glucose was used as substrate with a mean production of 1.01 ± 0.3 g/L and 0.58 ± 0.17 g/L for B. sphaericus EN3 and B. azotoformans EN16 respectively after 10 days. The surfactants were shown to be stable at various pH (2 - 12), temperature (50°C - 100°C) and salinity (2 - 10% NaCl) ranges. The biosurfactants were however more effective at pH of 8 to 10, 50 0 C and salinity of 2 to 4% NaCl. Chromatographic analysis revealed that the surfactants produced by both organisms were principally phospholipids. Therefore, the organisms were capable of producing substantial amounts of surfactants and harnessing their potentials would be essential.