Full Length Research Paper

Function and safety assessment of Lactococus lactis subsp. lactis LB12 as potential probiotic strain

Daodong Pan^{1, 2}* and Dezhen Zhang¹

¹Food Science and Nutrition Department of Nanjing Normal University, Nanjing 210097, China.

²Life Science and Biotechnology Faculty of Ningbo University, Ningbo 315211, China

*Corresponding author. E-mail: daodongpan@163.com. Tel: + 86 - 25 – 83598286. Fax: + 86 - 25 - 83707623.

Accepted 17 October, 2008

The effect of yogurt fermented by Lactococus lactis subsp. lactis LB12 isolated from traditional Chinese pickled cabbage on serum cholesterol and triacylglycerol levels were investigated in mice. In the same, the characterizations of the strain, such as acid-tolerance, bile-tolerance, antimicrobial activity, antibiotic sensitivity and safety were also examined. The serum total cholesterol, triglyceride and bile acid levels significantly decreased of mice given a high-cholesterol diet supplemented with yogurt fermented by Lactococus lactis subsp. lactis LB12. Characterization of L. lactis subsp. lactis LB12 showed that it was bile- and acid-tolerant, resistant to five commercial antibiotics tested, and possessed antimicrobial activity to pathogenic Escherchia coli and Staphylococcus aureus. None of morphological changes was noted as a result of L. lactis subsp. lactis LB12 treatment, nor were there significant differences in the visceral weight indices of the lymph nodes, spleen, bacterial translocation, or aberration rate of sperm of mice compared to control. The results indicated that L. lactis subsp. lactis LB12 might be effective as a probiotic with cholesterol-lowering activities.

Key words: Yogurt, Lactococus lactis subsp. lactis LB12, acid and bile tolerance, antimicrobial and antibiotic sensitivity, cholesterol-lowering effect.