(211e) Rhamnolipid Production by Long-Term Pseudomonas Aeruginosa Fermentation

Biosurfactans are considered as potential alternative to synthetic surfactants, since they are biodegradable and biocompatible. Rhamnolipids are one of the most promising biosurfactants due to their wide applications in bioremediation, enhanced oil recovery, anti-fouling, wound healing, etc. However, at this point rhamnolipids are not competitive with synthetic surfactants economically. The highly foaming nature of microbial cultures, low productivity and yield are some of the challenges leading to both very low amounts of rhamnlipid production and high production cost.  In this study, rhamnolipid production by P. aeruginosa fermentation under various levels of oxygen has been studied. The effects of two renewable carbon sources including glycerol and soybean oil on rhamnolipid production have been investigated as well. By using soybean oil, the ramnolipid productivity was doubled compared to the productivity obtained from glycerol as the carbon source. A stagnation of rhamnolipid production was observed after few hundred hours of fermentation process. Several possible hypotheses such as rhamnolipid inhibition, accumulation of other inhibitory compounds, nutrients depletion, and accumulation of fatty acids and/or glycerol were investigated. According to these findings, a long-term rhamnolipid fermentation with high productivity has been developed.