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IDENTIFICATION OF FECAL INDICATOR BACTERIA ISOLATES FROM AN ICE-COVERED RIVER
Citation:
Sparrow, E., C. Davenport, AND R. Gordon. IDENTIFICATION OF FECAL INDICATOR BACTERIA ISOLATES FROM AN ICE-COVERED RIVER. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/3-79/073 (NTIS PB81233017), 1979.
Description:
The membrane filter technique was used to enumerate the total coliform (TC), fecal coliform (FC), and fecal streptococcus (FS) populations at seven sample stations on an ice-covered river downstream from a major source of domestic pollution. From each membrane filter population (m-TC, m-FC, and m-FS), 210 typical colonies (30 per station) were selected for verification and biochemical differentiation of the component genera. The 210 m-TC isolates were Klebsiella pneumoniae (46.2%), Escherichia coli (20.5%), Enterobacter sp. (18.6%), other total coliforms (5.2%), and 9.5% which did not verify as total coliforms. Among these m-TC cultures, 114 were verified as fecal coliforms (gas production in EC broth at 44.5C). These 114 fecal coliforms were principally K. pneumoniae (53.5%) and E. coli (35.1%). In contrast, the 210 m-FC cultures were predominantly E. coli (77.6%), with K. pneumoniae (10.0%), other fecal coliforms (3.8%), and those not verified as fecal coliforms (8.6%). Of the 210 m-FS isolates, 167 were identified as enterococci, with 165 being Streptococcus faecalis biotypes. The results suggested the majority of these indicator bacteria originated from warm-blooded animal feces. Also, within each population, no overall differences in low temperature survival of the component genera were noted. However, the evidence does suggest that generic selectivity of the m-TC and m-FC techniques biases determination of the FC population composition, and that the m-FC technique underestimates the FC population density.