Maximize rhamnolipid production with low foaming and high yield.

Rhamnolipids are well-known microbial surfactants with many potential applications. Their production cost, however, remains high due to the severe foaming tendency in aerobic fermentation and the relatively low productivity and yield. In this study, we assessed the boundaries set by these constraints after optimization of basic parameters such as dissolved oxygen concentration (DO), pH and carbon sources. DO 10% and pH 5.5-5.7 were found optimal; cell growth and/or rhamnolipid production were slower at lower DO (5%) or pH (5.0) while foaming became hard to control at higher DO (30%) or pH (6.0 and 6.5). Although the Pseudomonas aeruginosa strain used was selected for its high rhamnolipid production from glycerol as substrate, soybean oil was still found to be a better substrate that increased specific rhamnolipid productivity to 25.8mg/g cells-h from the glycerol-supported maximum of 8.9mg/g cells-h. In addition, the foam volume was approximately halved by using soybean oil instead of glycerol as substrate. Analysis by liquid chromatography coupled with mass spectrometry revealed that rhamnolipid compositions from the two carbon sources were also very different, with primarily (82%) monorhamnolipids from soybean oil and more (64%) dirhamnolipids from glycerol. The optimized fermentation produced 42g/l rhamnolipids at a yield of approximately 47% and a volumetric productivity of 220mg/l-h. These values are among the highest reported.

Sodagari M ，Invally K ，Ju LK 《-》

Production of rhamnolipids in solid-state cultivation using a mixture of sugarcane bagasse and corn bran supplemented with glycerol and soybean oil.

Camilios-Neto D ，Bugay C ，de Santana-Filho AP ，Joslin T ，de Souza LM ，Sassaki GL ，Mitchell DA ，Krieger N ... -  《-》

Rhamnolipid biosurfactant production by strains of Pseudomonas aeruginosa using low-cost raw materials.

Rahman KS ，Rahman TJ ，McClean S ，Marchant R ，Banat IM ... -  《-》

Evaluation of different carbon and nitrogen sources in production of rhamnolipids by a strain of Pseudomonas aeruginosa.

Santos AS ，Sampaio AP ，Vasquez GS ，Santa Anna LM ，Pereira N Jr ，Freire DM ... -  《-》

Rhamnolipid production, characterization and fermentation scale-up by Pseudomonas aeruginosa with plant oils.

Gong Z ，Peng Y ，Wang Q 《-》