Selective enumeration of Lactobacillus casei from yogurts and fermented milk drinks

被引:93
作者
Ravula, RR [1 ]
Shah, NP [1 ]
机构
[1] Victoria Univ Technol, Sch Life Sci & Technol, Melbourne City Mail Ctr, Melbourne, Vic 8001, Australia
关键词
selective enumeration; ribose; L-casei; fermented milk drinks;
D O I
10.1023/A:1008829004888
中图分类号
Q5 [生物化学];
学科分类号
071010 ; 081704 ;
摘要
A selective medium (LC agar) was developed for enumeration of Lactobacillus casei populations from commercial yogurts and fermented milk drinks that may contain strains of yogurt bacteria (Streptococcus thermophilus and Lactobacillus delbrueckii sap. bulgaricus), probiotic bacteria (Lactobacillus acidophilus and bifidobacteria) and L. casei. Appropriate dilutions were pour-plated in specially formulated LC agar acidified to pH 5.1 and the plates incubated at 27 degrees C for 72 to 96 h under anaerobic conditions. Growth of S. thermophilus was prevented by adjusting pH to 5.1. L. delbrueckii ssp. bulgaricus did not ferment ribose as the carbon source, as a result the organisms did not form colonies. L. acidophilus formed colonies on MRS-ribose agar; however, this organism did not grow in the specially formulated LC agar containing ribose. Similarly, Bifidobacterium spp, did not form colonies in LC agar. L. casei formed colonies on LC agar.
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页码:819 / 822
页数:4
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