Rapid enzymatic detection of Escherichia coli contamination in polluted river water

Aims: The relationship between the rate Of beta -D-glucuronidase hydrolysis (GLUase-HR) and the E. coli concentration in rivers differing in the exten t of faecal pollution was investigated. It was hypothesized that the rate o f GLUase-HR is a better surrogate parameter for E. coli concentrations than estimated numbers of faecal coliforms (FC). Methods and Results: The GLUase-HR of the water sample filter residues was determined as the rate of cleavage of 4-methylumbelliferyl-beta -D-glucuron ide. FC and E. coli concentrations were enumerated using mFC and Chromocult Coliform agar, respectively. Regression analysis revealed that a 90% varia tion of the variable log GLUase-HR was directly related to the variable log E. coli concentrations. The observed relationship between the log of the F C count and the log of the GLUase activity could be explained by the hydrol ysis activity of the E. coli population, as E. coli is a part of the FC gro up. Conclusions: The data suggest that the log of the GLUase-HR can be used as a surrogate parameter for the log of the E. coli concentrations. Significance and Impact of the Study: GLUase-HR determination may provide a rapid alternative technique to estimate E. coli concentrations in freshwat ers.