Methods of analysis for bacterial contamination in environmental waters

Water pollution by faecal contamination is a serious problem due to the potential for contracting disease if the water is consumed untreated. Coliform bacteria Escherichia coli and Enterococci are used as primary indicators of contamination in fresh and marine water respectively. The presence and levels of these organisms are indicative of the presence of a number of pathogenic organisms of animal origin and thus for a potential threat to human health. The acceptable levels of indicator organisms are defined by legislation and vary for drinking, river, well and marine water.
This review will consider currently employed methods of analysis for coliform bacteria, compare them with recently developed procedures and evaluate advantages and limitations of different methods. Emphasis will be placed on methods which can be used on-site with laboratory procedures as confirmatory procedures. Established culture methods use chromogenic substrates for β-glucuronidase to identify E. coli and β-galactosidase to detect Enterococci . Rapid non-culture based fluorimetric procedures have been developed that can be used on-site. In addition to culture and biochemical procedures, advances have been made in developing genomic, proteomic and metabolomic methods. Methods must be quantitative in order to comply with legal norms and in this regard the potential involvement of biosensor technology will be of great value in successfully transferring laboratory procedures to the field.
The review will conclude with a recommendation of the most valuable laboratory and on-site methods for water analysis given the constraints of the current legal framework governing acceptable water quality.