BS EN ISO 9308-2:2014 - Water quality. Enumeration of Escherichia coli and coliform bacteria. Most probable number method
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BS EN ISO 9308-2:2014

Water quality. Enumeration of Escherichia coli and coliform bacteria. Most probable number method

Status : Current, Under review   Published : June 2012



ISO 9308-2:2012 specifies a method for the enumeration of E. coli and coliform bacteria in water. The method is based on the growth of target organisms in a liquid medium and calculation of the "Most Probable Number" (MPN) of organisms by reference to MPN tables. This method can be applied to all types of water, including those containing an appreciable amount of suspended matter and high background counts of heterotrophic bacteria. However it must not be used for the enumeration of coliform bacteria in marine water. When using for the enumeration of E. coli in marine waters, a 1?10 dilution in sterile water is typically required, although the method has been shown to work well with some marine waters that have a lower than normal concentration of salts. In the absence of data to support the use of the method without dilution, a 1?10 dilution is used. This method relies upon the detection of E. coli based upon expression of the enzyme b?D?glucuronidase and consequently does not detect many of the enterohaemorhagic strains of E. coli, which do not typically express this enzyme. Additionally, there are a small number of other E. coli strains that do not express b?D?g lucuronidase. The choice of tests used in the detection and confirmation of the coliform group of bacteria, including E. coli, can be regarded as part of a continuous sequence. The extent of confirmation with a particular sample depends partly on the nature of the water and partly on the reasons for the examination. The test described in ISO 9308-2:2012 provides a confirmed result with no requirement for further confirmation of positive wells.

Standard NumberBS EN ISO 9308-2:2014
TitleWater quality. Enumeration of Escherichia coli and coliform bacteria. Most probable number method
StatusCurrent, Under review
Publication Date30 June 2012
Normative References(Required to achieve compliance to this standard)ISO 19458, ISO/IEC Guide 2:2004, ISO 8199
Informative References(Provided for Information)ISO/TR 13843
International RelationshipsEN ISO 9308-2 (ISO 9308-2:2012
Amended ByCorrigendum, June 2014
DescriptorsCounting, Bacteria, Microorganisms, Coliform bacteria, Count methods (microbiology), Escherichia coli, Bacteria count methods, Microbiological analysis, Water, Water testing
Title in FrenchQualité de l'eau. Dénombrement des Escherichia coli et des organismes coliformes. Méthode du nombre le plus probable
Title in GermanWasserbeschaffenheit. Zählung von Escherichia coli und coliformen Bakterien. Verfahren zur Bestimmung der wahrscheinlichsten Keimzahl
ISBN978 0 580 84023 4
File Size1.303 MB

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