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Differential enumeration of silage inoculants based on utilization of enzymatic activity and antibiotic sensitivity of bacteria
Author(s) -
Kneifel W.,
Toros Arzu,
Viernstein H.
Publication year - 1994
Publication title -
journal of applied bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 0021-8847
DOI - 10.1111/j.1365-2672.1994.tb03042.x
Subject(s) - silage , agar , microbial inoculant , bacteria , enumeration , microbiology and biotechnology , lactic acid , agar plate , food science , biology , chemistry , mathematics , genetics , combinatorics
A plate count method for the selective enumeration of silage inoculants is described. On the basis of a screening of lactic acid bacteria for various physiological criteria, enzyme profiles and antibiotic sensitivity, three MRS‐based agar media were developed. Pediococci but not lactobacilli and enterococci produced colonies on MRS agar containing ampicillin at 5 mg 1 ‐1 , whereas only the enterococci grew on MRS agar containing clindamycin at the same level. On MRS‐X‐Gal agar with 50 μg ml ‐1 5‐bromo‐4‐chloro‐3‐indolyl‐β‐D‐galactopyranoside (X‐Gal) and 1% (w/v) glucose lactobacilli colonies were blue‐coloured (because of their β‐D‐galactosidase activity) while all cocci gave white colonies. The performance of these media was demonstrated by examining two commonly applied silage culture preparations.