Optimization Of Rhamnolipid Biosurfactant Production Condition And Its Effect On The Enzyme Production By Microorganism In Submerged Fermentation

The optimal culture medium of Pseudomonas aeruginosa AB93066 for producing rhamnolipid was obtained by orthogonal experiment. The addition of High- performance suspended macroporous carriers (HSMC) into this optimal culture medium increased the rhamnolipid production under almost the same cost. The result showed that the culture with HSMC exhibited 12.1% higher optical density compared to those observed in HSMC-free culture. Adding HSMC into fermentation broth triggered an increase in rhamnolipid production, which was 51.2% higher than the control, and the best period for rhamnolipid production was between 48-60h. The crude rhamnolipid was purified by column chromatography until monorhamnolipid and dirhamnolipid were obtained. Dirhamnolipid was used in the following studies.the effects of biosurfactant dirhamnolipid and anion chemical surfactant sodium dodecylsulfate (SDS) on lignin peroxidase, manganese peroxidase, laccase, CMCase and xylanase from Phanerochaete Chrysosporium were investigated during the whole process of submerged fermentation. The study compared the effects of biosurfactant dirhamnolipid with that of chemical surfactant SDS and offered some useful information on enhancing the enzyme activities for other researchers. The results indicated that dirhamnolipid at both concentration enhanced CMCase, xylanase and lignin peroxidase activities while inhibited manganese peroxidase activities, and the stimulative effect on lignin peroxidase activity and xylanase activity was much more effective, This study showed that the effects of dirhamnolipid on differnt enzymes produced by the same strain were different. During the whole fermentation, dirhamnolipid at the concentration of 0.013% obviously increased the lignin peroxidase, and the peak lignin peroxidase activity was 61.98% higher than that of the control. However, chemical surfactant SDS at both concentrations inhibited or had no effect on the four enzyme activities. Laccase produced by Phanerochaete Chrysosporium was very low under all the treatments.