KMID : 0903519930360030191
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Journal of the Korean Society of Agricultural Chemistry and Biotechnology 1993 Volume.36 No. 3 p.191 ~ p.196
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Detection of Bifidobacteria by ¥á - galactosidase activity
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Abstract
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This method using the synthesis substrate of 5-bromo-4-chloro-3-indolyl-¥á-galactoside (X-¥á-Gal) was examined for the differential enumeration of Bifidobacteria and lactic acid-producing bacteria. Bifidobacteria possess a high level of ¥á-galactosidase activity. Biffdobacterium longum KCTC 3215 exhibited the highest ¥á-galactosidase specific activity (8.57 units/§· protein). Determination of ¥á-galactosidase activity using the PNPG procedure showed that Lactobacillus, Streptococcus, Pediococcus, and Leuconostoc strain had lower ¥á-galactosidase activity as compared to Bifidobacteria. The X-¥á-Gal based medium is useful to identify Bifidobacteria among lactic acid-producing bacteria since the enzyme action of ¥á-glactosidase spilts X-¥á-Gal substrate and releases indol which impacts a blue color to Bifidobacterial colonies on agar plates. All strains of Bifidobacteria appeared as blue colonies on MRS agar medium supplemented with 100 ¥ìM X-¥á-Gal while colonies of other lactic acid-producing bacteria appeared white or light blue.
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