Lipopeptide production from Bacillus sp. GB16 using a novel oxygenation method

During lipopeptide (biosurfactant) production by Bacillus sp. GB16, conventional aeration method using added antifoam agent was unsuccessful due to the excessive formation of foam and the inhibitory effects of the antifoam chemical. A novel integrated method was developed to increase the dissolved oxygen concentration during the microbial production of biosurfactant lipopeptides. This novel method consisted of adding hydrogen peroxide to the medium, which decomposed to oxygen and water by cell's catalase and adding a vegetable oil and Ca-stearate to the medium as antifoam agents, as well as oxygen vectors. The dissolved oxygen concentration could be controlled by the automatic addition of hydrogen peroxide to the bioreactor. A significant improvement, i.e., suppression of foaming and, therefore, a three-fold extension of the cultivation time and, consequently, remarkable increase in the lipopeptide production could be achieved. This result showed that a novel aeration method was effective, especially when excessive foaming caused problems during microbial production of biosurfactant.