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

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 p H 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 16 S r DNA 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 and16 S r DNA sequence analysis,the strain was identified as Enterococcus faecium.