Ecology, Environment and Conservation Paper

COMPARISON OF READYCULT CONFORM-50 WITH CONVENTIONAL METHODS FOR DETECTION OF TOTAL COLIFORMS AND FAECAL ESCHERICHIA COLL IN DRINKING WATER SAMPLES

Malkit Singh, Neelam Taneja, Devinder Bhatti and Meera Sharma

Abstract

Readycult coliform-50 (RCC-50) system was compared with traditional and most widely used Most Probable Number-Multiple Tube Fermentation" (MPN-MTF) method for detection of coliforms and faecal Escherichia coli in drinking water samples. Fifty water samples, collected from four different sources (Tap, hand pump, open well and tube well) were tested by both the methods (RCC-50 and MPN-MTF). RCC-50 was found to be equally sensitive in detecting coliform and faecal E.coll if counts of these organisms were higher (>5 coliforms/ 100 ml) as detected by MPNMTF method (Sensitivity 100%). But for the samples where coliform counts were low, the sensitivity of RCC-50 was found to be as low as 62.5%. In general for detection of coliforms, the sensitivity of RCC-50 was 88.88% and for faecal Ecoh it was 80% as compared with MPN method,The lowest limit of RCC-50 for detection of faecal E.coli was found to be 3 E.coli bacteria/I00 ml of water sample under experimental conditions. RCC-50 produced blue-green colour with light blue fluorescence under UV light with only Esch.coli and not with any of the other organism tested. It is suggested that RCC-50 is a simple, less laborious and less time consuming system which can be used routinely for screening of untreated drinking water samples where coliforrn counts are expected to be high. But the utility of this kit for testing treated water samples where coliform count is low, needs further evaluation with large number of samples. Its lowest limit of detecting coliforms also needs to be determined by comparing with membrane filter technique.