产胞外多糖乳球菌的优化培养

Opatimal culture of an exopolysaccharide-producing Lactococcus lactis

以苯酚硫酸法测定乳酸乳球菌乳酸亚种WH-C1在不同培养基中的胞外多糖合成量,试验以WHEY作为基础培养基,比较了添加不同碳源、氮源对EPS合成的影响,并采用正交实验L9(34)对碳源、氮源的添加量及培养基初始pH进行了优化,确定最佳组合为:葡萄糖添加量15 g/L,胰蛋白胨添加量5 g/L,培养基初始pH值为6.5。研究了不同培养温度和接种量条件下该菌株的EPS合成曲线,结果表明温度对发酵液中EPS总积累量的影响较大,通过本研究确定了乳酸乳球菌乳酸亚种WH-C1最佳培养条件为:培养温度25℃,接种量为2%(体积分数),培养时间32 h,EPS合成量为325.8 mg/L。

Whey medium was selected as the base culture medium for exopolysaccharide producing of Lactococcus lactis subsp, Lactis WH-C1 according to the EPS yield determinedetection with phenol-sulfuric acid method. When it was cultured in different media, The effects of different carbon sources and nitrogen sources on exopolysaccharide production were also studied. An orthogonal experiment L9 （3^4） was carried out to explore the interactive effect of different amounts of carbon source, nitrogen source and initial pH of medium. The best medium com- position was： 15 g/L of glucose, 5g/L of tryptone, and the initial pH of 6.5. Later on, the synthesis curves of exopolysaccharide cultured on conditions of different culture temperature and inoculation percentage were tested. The result indicated the culture temperature effected the total accumulation of polysaccharide strongly. While the optimized culture condition was： culture temperature of 25 ℃, inoculation percentage of 2% and culture time of 32 h, with a corresponging EPS yield of 325.8 mg/L.