Abstract: The cholesterol-reducing probiotics——LQ-12 was identified as Lactococus.lactis subsp.lactis. As imitatinggastroenteric environments,such as low pH(1.5～4.5) and high bile salt(0.1%～0.4%),the antagonistic properties of LQ-12were studied.At the same time,the antimicrobial activities on pathogenic E.coli and S.aureus in the intestinal tract and antibiotictolerance of LQ-12 were also studied.The results indicated that LQ-12 survived at pH 1.5～4.5 after 4h culture and the livingbacterial number could reach 106cfu/ml;that living bacterial number were also above 106cfu/ml at the 0.1%～0.3% bile salt andeven survived in 0.4% after 6h culture;that antimicrobial activities to the pathogenic E.coli and S.aureus were obvious;andthat the tolerance to Ampicillin, Tetracycline, Gentamicin, Roxithromycin, Cefradine was power. So LQ-12 can be used as microbialpreparation and starter for yoghurt.

Key words: lactic acid bacteria, antagonistic property, antimicrobe, medicine tolerance