Author(s)

J. Koschelnik, W. Vogl, M. Epp, M. Lackner

Abstract

Microbiological cultivation methods estimate the number of bacteria in water samples mainly as an amount of Colony Forming Units in 100 ml (CFU/100ml) or as a Most Probable Number of fecal bacteria in 100 ml (MPN/100ml). The growing amount of molecular methods for specific detection of fecal bacteria allows rapid measurement without the need for cultivation. These methods could determine the presence of specific genetic markers of fecal bacteria in water expressed in Genomic Equivalent Units per 100 ml (GEU/100ml) or Target Sequence Copy (TSC) per 100 ml. Analysis of enzymes, such as β-D-glucuronidase in indicator bacteria have been used for many years to quantify feces-associated contamination, but the measurement parameter which allows the comparison of the obtained results is not clearly defined. In this work we are introducing a novel parameter: enzymatic activity of beta-D-glucuronidase expressed in Modified Fishman Units per 100 ml of water sample (MFU/100ml). A fully automated device to detect enzymatic activity above 0.001 MFU/100ml in freshwater without sample pretreatment within less than 60 minutes was developed and subjected to field tests. The instrument measures enzymatic activity by detection of accumulated reaction product. Due to the short measurement time, the technology can be used both for water quality monitoring purposes and for process control applications.

Keywords

E. coli, fecal contamination, water monitoring, enzymatic activity, glucuronidase, modified fishman units, MFU/100ml, ColiMinder