Section 10
Chapter 9,703

Use of 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside for the isolation of beta-galactosidase-positive bacteria from municipal water supplies

Ley, A.; Barr, S.; Fredenburgh, D.; Taylor, M.; Walker, N.

Canadian Journal of Microbiology 39(9): 821-825


ISSN/ISBN: 0008-4166
PMID: 10755843
DOI: 10.1139/m93-122
Accession: 009702322

Download citation:  

A new medium, mX-Gal, has been developed for the membrane filter enumeration of beta-galactosidase-positive bacteria in municipal water supplies. mX-Gal medium contains the chromogenic beta-galactosidase substrate 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside (X-Gal). All Aeromonas, Citrobacter, and Enterobacter strains isolated from raw water on mX-Gal medium were beta-galactosidase positive. In contrast, only 10 to 20% of these strains produced a red colony with a metallic sheen on m-Endo agar LES medium. Of 674 chlorinated water samples analyzed for total coliforms on m-Endo agar LES medium and for beta-galactosidase-positive bacteria on mX-Gal medium, 18 that were negative for coliforms on m-Endo agar LES showed beta-galactosidase-positive bacteria on mX-Gal. Of a total of 50 beta-galactosidase-positive bacteria isolated from these samples, 76% were identified as Aeromonas hydrophila.

PDF emailed within 0-6 h: $19.90