豆腐酸浆老汤中产酸菌的分离筛选与鉴定

Isolation and identification of acid- producing lactic acid bacteria from tofu acid whey

利用MRS选择性培养基,从分别采自山东邹平、陕西榆林、河北涞源、云南石屏、云南建水及云南元阳的6份酸浆老汤中分离纯化出12种菌落形态不一样的乳酸菌,分别采用MC改良培养基和发酵黄浆水p H及产酸量的监测对12种菌进行初筛及复筛,筛选出一株产酸较快、较高的乳酸菌,并对该菌株进行了菌落形态、生理生化及16S r DNA序列分析的鉴定实验,结果表明:该菌株为革兰氏阳性菌,菌落特征为白色,圆形,表面突起,不透明,边缘整齐,镜检发现该菌为球菌、直径为0.8μm,四联或成串排列,经生理生化及16S r DNA序列鉴定确定该菌为肠球菌属中的屎肠球菌(Enterococcus faecium),遗传稳定性较好。

12 strains of lactic acid bacterium were isolated from 6 different tofu acid whey from Shandong zouping, Shanxi yulin,Hebei laiyuan,Yunnan shiping,Yunnan jianshui and Yunnan yuanyang by MRS selective medium, 12 strains of lactic acid bacterium were preliminary screed by MC selective medium.On the basis of the measurement of fermented tofu whey＇ s pH values and lactic acid production in different fermented time,the high acid producing strain was screened out.The identification tests of colony morphology,physiology and biochemistry and 16S rDNA sequence analysis were studied for the acid producing strain. The results showed that the strain was gram- positive,circular, white, surface convex, opaque, and entire. According to physiology and biochemistry and 16S rDNA sequence analysis,the strain was identified as Enterococcus faecium.