Rapid detection of coliform bacteria and influence of non-target bacteria

Enzymatic hydrolysis of fluorogenic substrates (4-methylumbelliferyl-beta-D-galactoside, 4-methylumbelliferyl-beta-D-glucuronide) has been used for rapid (25min) detection of indicators of faecal water pollution, i.e. coliform and thermotolerant coliform bacteria. In the present work, enzymatic activities and different groups of bacteria (i.e. thermotolerant coliforms, coliforms, beta-galactosidase positive and beta-glucuronidase positive bacteria) from sewage effluent and polluted river water have been investigated. Ratios of the order of 1:10 between coliforms and beta-galactosidase positive bacteria were demonstrated. The contribution from beta-galactosidase positive non-coliform bacteria to the measured enzyme activity should not, therefore, be neglected. Numbers of beta-glucuronidase positive non-coliforms indicate interference of this group in the rapid assay. (C) 1997 IAWQ. Published by Elsevier Science Ltd.