干酪乳杆菌LC2W胞外多糖提取工艺研究

Optimization of Preparation Procedures for Exopolysaccharides from Lactobacillus casei LC2W

对影响干酪乳杆菌LC2W胞外多糖提取的主要工艺参数进行了研究。发酵液经超滤浓缩,三氯乙酸脱蛋白,乙醇沉淀等处理,得到粗多糖。单因素和正交试验结果表明,用截留分子量为10 kDa的超滤膜将发酵上清液浓缩4倍后,用终浓度6%的三氯乙酸脱蛋白,再用5倍体积95%乙醇4℃沉淀24 h,多糖提取效果较佳。在此条件下,蛋白脱除率可达88.35%,EPS提取率可达92.17%。

The parameters involved in preparation of exopolysaccharides（EPS） from Lactobacillus casei LC2W were studied.Supernatant fermented MRS broth by Lb.casei LC2W containing EPS was firstly concentrated by ultrafiltration,then proteins in the retentate were eliminated by addition of trichlorocetic acid,and finally exopolysaccharides were precipitated by alcohol.Results of single factor test and orthogonal experiments showed the optimized EPS preparation procedure was as the following：the supernantant of cultured MRS broth was firstly ultrafiltrated to 1/4 of original volume by using MWCO of 10 kDa membrane,the proteins in the retentate was eliminated by TCA at an ultimate concentration of 6%（m/V）,and finnally 5 volumes of 95% ethanol alcohol of the retentate were added and the EPS was allowed to precipate at 4℃ for 24 h.During this procedure,88.35% of the proteins was eliminated and the EPS recovery rate was reached to 92.17%.