Comparison of the direct enzyme assay method with the membrane filtration technique in the quantification and monitoring of microbial indicator organisms - seasonal variations in the activities of coliforms and E. coli, temperature and pH

Wutor, V. C. and Togo, C.A. and Pletschke, B.I. (2007) Comparison of the direct enzyme assay method with the membrane filtration technique in the quantification and monitoring of microbial indicator organisms - seasonal variations in the activities of coliforms and E. coli, temperature and pH. Water SA, 33 (1). pp. 107-110. ISSN 0378-4738

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Abstract

The aim of this project was to monitor variations and relationships between coliform and E. coli counts, the activities of their marker enzymes GAL and GUD, and temperature and pH over a period of 12 months in river samples obtained from the Eastern Cape, South Africa. Several polluted water samples were collected for direct coliform β-D-galactosidase (B-GAL) and Escherichia coli β-D-glucuronidase (B-GUD) assays and the membrane filtration technique. While all the samples showed enzyme activities, not all exhibited growth on CM1046 media. Variation in B-GAL activity (40%) was observed between November (highest activity month) and May (lowest activity month). The highest and lowest B-GUD activities were observed in the months of September and May/June, respectively. The sensitivity of the spectrophotometric assay method was indicated by a limit of detection (LOD) of 1 coliform forming unit (CFU)/100 mℓ and 2 CFU/100 mℓ for coliforms and E. coli, respectively. There was a significant (P < 0.05) positive correlation between E. coli counts and GUD activity (R2 = 0.8909). A correlation of R2 = 0.9151 was also observed between total coliforms and B-GAL activity, even though the CFUs were not evenly distributed. Direct enzyme assays were also shown to be more sensitive than the membrane filtration (MF) technique.

Item Type:Article
Uncontrolled Keywords:Chlorophenol red β-D-galactopyranoside (CPRG); Chlorophenol red (CPR); Coliforms; E. coli; p-nitrophenyl (PNP); p-nitrophenyl-β-D-glucuronide (PNPG)
Subjects:Y Unknown > Subjects to be assigned
Divisions:Faculty > Faculty of Science > Biochemistry, Microbiology & Biotechnology
ID Code:1372
Deposited By: Mrs Eileen Shepherd
Deposited On:15 May 2009
Last Modified:01 Aug 2012 13:23
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