Premium
Comparison of indole production and β‐glucuronidase activity for the detection of Escherichia coli in a membrane filtration method
Author(s) -
Schets F.M.,
Havelaar A.H.
Publication year - 1991
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1111/j.1472-765x.1991.tb00626.x
Subject(s) - escherichia coli , reagent , membrane filter , filtration (mathematics) , indole test , glucuronidase , membrane , chromatography , bacteria , chemistry , glucuronide , enumeration , biology , fluorescence , microbiology and biotechnology , biochemistry , enzyme , metabolism , gene , statistics , genetics , mathematics , combinatorics , physics , quantum mechanics
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.