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THE DETERMINATION OF THE COLI‐AEROGENES CONTENT OF MILK AND DAIRY EQUIPMENT BY PLATING ON VIOLET RED BILE AGAR INCUBATED AT 30°
Author(s) -
DRUCE R. G.,
BEBBINGTON NANCY B.,
ELSON K.,
HARCOMBE JEAN M.,
THOMAS S. B.
Publication year - 1957
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.1365-2672.1957.tb04507.x
Subject(s) - agar , bacteria , food science , agar plate , milking , escherichia coli , biology , raw milk , macconkey agar , enterobacter aerogenes , microbiology and biotechnology , zoology , biochemistry , genetics , gene
SUMMARY: Violet red bile agar (VRB) incubated at 30° for 20–24 hr was as good an indicator of coli‐aerogenes bacteria in milk as MacConkey's broth. A high proportion (82%) of the large, deep red colonies considered to be formed by coli‐aerogenes bacteria were confirmed as such. A British brand of dehydrated VRB agar was as suitable as an American brand of this medium for determining the coli‐aerogenes content of milk. All the strains of typical coli‐aerogenes bacteria tested formed red colonies. In a small proportion of cases the diameter was less than 0·5 mm. The only other milk bacteria which formed colonies resembling those of coli‐aerogenes organisms were some acid forming strains of Gram‐negative rods. Coli‐aerogenes bacteria, determined on VRB agar at 30°, generally constituted only a small proportion of the microflora of fresh raw milk and of farm dairy equipment.