Evaluation of Recovery Methods to Detect Coliforms in Water

AUTOR(ES)

Bissonnette, G. K.

RESUMO

Various recovery methods used to detect coliforms in water were evaluated by applying the membrane filter chamber technique. The membrane filter chambers, containing pure-culture suspensions of Escherichia coli or natural suspensions of raw sewage, were immersed in the stream environment. Samples were withdrawn from the chamber at regular time intervals and enumerated by several detection methods. In general, multiple-tube fermentation techniques gave better recovery than plating or membrane filtration procedures. The least efficient method of recovery resulted when using membrane filtration procedures, especially as the exposure period of the organisms to the stream environment increased. A 2-h enrichment on a rich, nonselective medium before exposure to selective media improved the recovery of fecal coliforms with membrane filtration techniques. Substantially enhanced recoveries of E. coli from pure-culture suspensions and of fecal coliforms from raw-sewage suspensions were observed when compared with recoveries obtained by direct primary exposure to selective media. Such an enrichment period appears to provide a nontoxic environment for the gradual adjustment and repair of injured cells.

Documentos Relacionados

• Failure of the most-probable-number technique to detect coliforms in drinking water and raw water supplies.
• Evaluation of methods to detect oxidase activity in the genus Pasteurella.
• Evaluation of Different Methods To Detect Methicillin Resistance in Small-Colony Variants of Staphylococcus aureus
• Evaluation of Five Membrane Filtration Methods for Recovery of Cryptosporidium and Giardia Isolates from Water Samples
• Evaluation of the 7-h membrane filter test for quantitation of fecal coliforms in water.