The Effect of pH on Biosurfactant Production by Bacillus Subtilis DSM10

Abstract

The genus Bacillus has long been known for its ability to produce many industrially useful products. These bacteria mostly produce extracellular products like organic acids, enzymes and biosurfactants. In this paper, the production of surfactin using the Bacillus subtilis strain DSM10 is investigated. Biosurfactant was produced in a lab-scale 1-liter fermenter. pH control using different bases (NH 4 OH and NaOH) was compared to observe whether the amount of produced biosurfactant or the quality of the product was influenced. The formation of the product was followed by measuring the surface tension, and the product formed was analyzed by reversed-phase chromatography. The investigation of the effect of pH control showed that it can be omitted during the fermentation of the biosurfactant. The highest concentration of surfactin ( 5 g/L) was achieved without pH control in contrast with when the pH was kept constant ( pH = 7 ).