AWWA ACE63190

The objective of this slide presentation was to evaluate enumeration methods for the detection of coliform bacteria in water samples using a precise number of organisms. Escherichia coli (ATCC = 11775) and Enterobacter aerogenes (ATCC = 13048) BioBall™ cultures were used. All methods were tested 10 times using each culture and the 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 Colisure™ multiple 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 and consistent results(1 mL); Colilert produced the most consistent results with the lowest coefficient of variation (100 mL); MF, Colisure and MPN may be producing results with greater variability; and, BioBall™ is a very useful quality control tool for evaluating the efficiency of water testing procedures. Includes figures.