AWWA ACE63190

AWWA ACE63190 Evaluation of the Methods for Enumerating Coliform Bacteria from Water Samples Using Precise Reference Standards
Conference Proceeding by American Water Works Association, 06/01/2006

Wohlsen, T.; Bates, J.; Vesey, G.; Robinson, W.A.; Katouli, M.; Napoli, M.

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The objective of this slide presentation was to evaluate enumeration methods for the detection ofcoliform bacteria in water samples using a precise numberof organisms. Escherichia coli (ATCC = 11775) and Enterobacteraerogenes (ATCC = 13048) BioBall cultures were used.All methods were tested 10 times using each culture andthe mean number ¿¿¿¿ SD of all readings was calculated. Eight methods were evaluated using BioBall cultures:membrane filtration;mFC and mLS;defined substrate technology systems;Colilert and Colisuremultiple tube fermentation (MPN);Petrifilm;standard plate count; and, pour and spread plate method. Results of the methods are given, and conclusions were that: Petrifilm and PCA-P produced the most accurate andconsistent results(1 mL);Colilert produced the most consistent results with the lowestcoefficient of variation (100 mL);MF, Colisure and MPN may be producing results withgreater variability; and,BioBall is a very useful quality control tool for evaluatingthe efficiency of water testing procedures. Includes figures.