Conventional culture for water quality assessment: is there a future?

Abstract

SUMMARY Conventional culture for the detection, enumeration and identification of micro‐organisms has been the traditional tool of the microbiologist. It is, however, time‐consuming and labour‐intensive and confirmed results often require several days of analysis. Culture may not grow the organisms being sought and for enumeration may only detect a small proportion of the total population. However, it does have the advantage of being simple to use and relatively inexpensive. It is also a direct means of assessing cell viability. Novel fluorogenic dyes and fluorgenic and chromogenic substrates have overcome some of these problems by providing a means of rapid and specific detection and enumeration whilst removing the need for subculture and confirmation tests. Immunological tests such as ELISA have significantly reduced analysis time by providing specific target organism detection. Molecular techniques have removed the need for culture. Improvements in sensitivity, and removal of the inhibitory nature of sample matrices, have allowed analysts to detect low levels of micro‐organisms but the questions of viability and comparability with cultural techniques still remain. Are we about to see a change of culture in water quality assessment, or can cultural techniques be developed that reduce analysis time to a few hours and can rapid methods be used for detecting the presence and viability of organisms?

The microbial status of natural waters in a protected wilderness area

“…The membranes were then incubated on Membrane Lactose Glucuronide Agar (m-LGA) contained in sterile 50 mm petri dishes following the methods of Sartory and Watkins (1999) and Watkins and Jian (1997). The media were made up in a sterile laboratory, CREH, in Leeds and were suitable for use for up to seven days when kept cool.…”

Use of the indirect immunofluorescence method for detection and enumeration of Escherichia coli in seawater samples

“…Conventional methods prescribed for its detection, however, are affected by certain limitations (e.g. long incubation and response times, low accuracy) which make their application to seawater monitoring inadequate (Volterra and Garizio 1997;Sartory and Watkins 1999). Rapid techniques developed in recent times include speci®c enzymatic assays based on the evaluation of the presence of b-glucuronidase using¯uorogenic substrates, such as 4-methylumbelliferyl-b-D-glucuronide (MUG test; Caruso et al 1998a), or immunological methods such as thē uorescent antibody technique (immuno¯uorescence) for the speci®c detection of enteropathogenic serotypes (Zaccone et al 1995).…”

Detection and Typing of Campylobacter jejuni and Campylobacter coli and Analysis of Indicator Organisms in Three Waterborne Outbreaks in Finland

“…According to most regulations, a 100-ml sample of drinking water should not contain any coliform bacteria (27); a prerequisite for use of this volume is that the safety of the drinking water has been assessed by risk analysis, and any possibility of fecal contamination thus is minimized (27). Microbiological analysis is an additional tool for safety assessment.…”