ヨーグルト製造に使用する各種乳酸菌の選択培地の開発
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概要
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When simple handmade yogurt was prepared using the mixture of Streptococcus thermophilus NB-1, Lactobacillus bulgaricus NB-15, Lactobacillus acidophilis NB-20 and Bifidobacterium longum NB-26 as a starter, selective media were needed for detecting the bacterial flora, and then developed. TSM agar was devised as a selective medium for S. thermophilus NB-1 by pH (8.0) arrangement of Tryptosoy agar; MSN-LBS agar for L. acidophilus NB-20 by the addition of NaN_3 to LBS agar in which glucose was replaced with maltose and sucrose; BSM agar for B. longum NB-26 by decreasing antibiotic amounts in BS agar. A selective medium of L. bulgaricus NB-15 was not devised, but the viable counts was enumerated by subtracting numbers of colonies on MSN-LBS agar from the ones on modified LBS agar. Tryptosoy agar, LBS agar and BL agar, a main compoment of BS agar are commercial media, while BS agar is well known as a medium for Bifidobacterium isolation from intestinal materials. The developed media were used for analysis of the flora in the handmade yogurt incubated at 37℃ for 6 hours. At the end of incubation the viable counts of S. thermophilus NB-1 and L. bulgaricus NB-15 increased up to 1000 times of those at 0 hours, with being 1.5×10^9/ml and 6.5×10^8/ml, respectively, while those of L. acidophilus NB-20 and B. longum NB-26 increased only 10 times, with being 5.6×10^4/ml and 2.3×10^6/ml, respectively.
- 1999-11-27