Optimization of Surfactin Production by Bacillus subtilis ATCC 6633 in a Miniaturized Bioreactor

In recent years, biosurfactants due to wide applications in chemical, petroleum, food and pharmaceutical industries, have been widely considered by researchers. Biosurfactants are produced by a series of microorganisms, so it is important to screen culture medium and operating conditions in miniaturized bioreactors prior to scaling up to large bioreactors. In this study, using a kind of miniaturized bioreactor called ventilation flask, optimal production conditions, including filling volume and shaking frequency to produce a surfactin-type biosurfactant by Bacillus subtilis ATCC 6633, were examined. Moreover, the effect of oxygen transfer rate (OTR) on the surfactin production was investigated according to Amoabediny and Buechs model. The results indicated that the maximum biomass and biosurfactant yield which obtained under optimal conditions (filling volume of 15 mL and shaking frequency of 300 rpm) were evaluated 0.3 g/L/h and 0.0485 g/L/h, respectively. Also, at the same conditions, the amount of surface tension decreased from 60.5 mN/m to 31.7 mN/m and the maximum oxygen transfer rate (OTR sub(max)) obtained as 0.01 mol/L/h.