Lactobacillus Producing Extracellular Polysaccharides In Plant Research

Exopolysaccharide(EPS), one kind of carbohydrates, was secreted by lactic acid bacteria during its growth metabolism. EPS produced by lactic acid bacteria can increase the viscosity and organizational status of dairy products, and it was widely used as stabilizer, gelling agent and thickener.The researching progress of EPS at home and abroad was introduced in the paper. Physiological functions, factors affecting the production of EPS and applications was summarized. The optimizing fermentation conditions, purification and component analysis of EPS were investigated in this research.Glucose, MnSO4, peptone, pH, fermentation time, inoculum concentration and fermentation temperature, which affect the yield of EPS produced by Lactobacillus plantarum, was studied by single-factor test. The fractional factorial design was employed to screen on factors which significant variables to improve the yield of EPS. The results showed that the addition of glucose, pH and fermentation time were significant variables to improve the yield of EPS. A three-level Box-Behnken factorial design was employed for maximizing the EPS. The optimal conditions was glucose4.68%, MnSO40.006%, peptonel%, inoculum concentration3%, pH6.32, fermentation time27.51h, fermentation temperature 30℃. The results indicated that EPS was 1.5 times higher in this condition than before.In order to improve the extraction rate of EPS, the abstraction conditions were optimized. The results showed that the best optimization condition was:it should adopt 3times the volume of ethanol to settle down the EPS. Removal rate of protein reach 89.51%, loss rate of EPS was 18.12%.DEAE-52 was established to isolate and purify the EPS.The result of qualitative analysis showed that the EPS was composed of rhamnose, mannose, glucose by thin-layer chromatography. Infrared spectrum showed that the sample had the characteristic absorption peak of polysaccharides.