Species composition and growth-temperature characteristics of coliforms in relation to their sources.

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Abstract
Species composition and growth-temperature characteristics of coliforms isolated from several types of environmental samples were investigated. It was possible to divide these isolates into 8 distinct groups, 6 species groups and 2 unidentified, on the basis of their biochemical properties. The isolates included in the unidentified groups, giving IMViC [indole, methyl red, Voges-Proskauer, citrate] reactions of --++ and -+-+, were tentatively termed typical psychrotrophic coliform (TPC) bacteria because of their ability to grow at 1.degree. C. The TPC bacteria and Citrobacter freundii constituted the normal coliform flora of mountain soil and stream water samples. Escherichia coli and Klebsiella pneumoniae were major predominant coliforms in polluted river water and sewage samples, the former being most common in human feces samples. In testing the growth response at different temperatures, the isolates of E. coli and the TPC bacteria showed relatively constant temperature preferences regardless of origin; other coliform members gave varied results dependent on their sources. The results provided circumstantial evidence that environmental population densities of coliforms able to grow in EC broth at .gtoreq. 43.degree. C but not in ordinary nutrient broth at 5.degree. C within 7 days of incubation are directly proportional to the degree of potential fecal contamination.