Enhancing surfactant production in Bacillus subtilis UTB96 by fermentation optimization

A biocontrol bacterium, Bacillus subtilis is well known for producing wide spectrum of antimicrobial compounds. Among these products, biosurfactant compounds such as surfactin have high importance. Biosurfactants that are produced by the microorganisms are applied in the various aspects of industry, medicine and agriculture because of their low toxicity and individual properties. However, these compounds are not produced in high quantity due to their low production yield and high purification cost. In the current study for investigating the production of surfactin in the isolate (UTB96), recognition of srf gene and determination of the amount of surfactin production, we used Drop collapse, PCR and HPLC methods. Molecular analysis with specific primer indicated that the isolate had srf gene. To optimize the fermentation process, influence of various inducers and physiochemical factors were studied on the biomass and surfactin production. The results indicated that maximum surfactin production occurred after amending the culture medium with glucose (1.243 g/l) solution. After that influence of the combined inducer elements were studied in increasing the amount of surfactin production. Results revealed that maximum production (5.055 g/l) was done in the presence of Fe2+, Mn2+ and Mg2+ mixture in the culture medium. The results also showed that the amount and the type of the food sources had remarkable impact on the surfactin production efficiency. The changes in the amount and composition of the food sources therefore, could be economically considered for the commercial production of this compound.