Comparison of indole production and β‐glucuronidase activity for the detection of Escherichia coli in a membrane filtration method

In a membrane filter method for the enumeration of Escherichia coli in water samples, the James' indole reagent has several advantages over the commonly used diaminobenzaldehyde (DAB) reagent. Results with James' reagent were easier to read because the red colour of positive colonies was m...

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Bibliographic Details
Published in:Letters in applied microbiology 1991-01, Vol.13 (6), p.272-274
Main Authors: Schets, F.M., Havelaar, A.H.
Format: Article
Language:English
Subjects:
Bacteriological methods and techniques used in bacteriology
Bacteriology
Biological and medical sciences
Fundamental and applied biological sciences. Psychology
Microbiology
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Summary:In a membrane filter method for the enumeration of Escherichia coli in water samples, the James' indole reagent has several advantages over the commonly used diaminobenzaldehyde (DAB) reagent. Results with James' reagent were easier to read because the red colour of positive colonies was more intensive and developed within a few minutes without exposure to UV light. DAB‐coloured colonies were pale pink with a diffuse pink zone surrounding the colonies after 30 min of exposure to UV‐source radiation. Incorporation of 4‐methylumbelliferyl‐β‐D‐glucuronide (MUG) into the selective medium to detect E. coli by means of β‐glucuronidase‐activity gave discouraging results. Fluorescence was difficult to read on membrane filters incubated on this medium and 14% of E. coli strains were β‐glucuronidase‐negative.
ISSN:0266-8254
1472-765X
DOI:10.1111/j.1472-765X.1991.tb00626.x