Effect of Aeration Rate on Biosurfactin Production in a Miniaturized Bioreactor

Recently, the production of biosurfactants in bioreactors and their use in various pharmaceutical,
chemical and food industries have been developed. Optimum production is directly related to the physicochemical
condition of culture medium (such as pH and temperature) and engineering parameters of bioreactors (such as
aeration rate, volume of operation and the amount of energy input). Understanding the gas transfer in shaken
bioreactors equipped with a sterile closure is advantageous to avoid oxygen limitation or carbon dioxide
inhibition of a microbial culture. In this study, the effect of aeration rates (due to using different design
closures) on the amount of biosurfactin production by Bacillus subtilis ATCC 6633 in a ventilation flask as a
miniaturized bioreactor was investigated. The highest biosurfactin concentration (0.0485 g/L/h) was obtained
in the optimum conditions in which the amount of filling volume and shaking frequency were 15 ml and 300
rpm, respectively. The specific aeration rate (qin) and maximum oxygen transfer rate (OTRmax), were calculated
1.88 vvm and 0.01 mol/L/h, respectively. The results showed the significant biosurfactin productivity increase
under non-oxygen limiting condition.