Abstract: In this paper,we use the Lactococcus lactis subsp.lactis of bile salt hydrolase screened from kefir grains to the study environment factors of increasing enzyme vires. For four factors to affect synthesize of bile salt hydrolase,the fermentation conditions of high yield bile salt hydrolase were determined by the four factors and three levels orthogonal test L9(34). As followglucose 2%,soya-peptone 2%,fermentation temperature 37℃,amount of inoculation 2%. In optimization conditions,the vires of bile salt hydrolase is 11.84 times before optimize.

Key words:  , Lactococcus lactis subsp.lactis； bile salt hydrolase； optimization conditions；