This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Isobe, K. O. Articles by Takada, H. Search for Related Content PubMed PubMed Citation Articles by Isobe, K. O. Articles by Takada, H. Agricola Articles by Isobe, K. O. Articles by Takada, H.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, February 2004, p. 814-821, Vol. 70, No. 2
0099-2240/04/$08.00+0     DOI: 10.1128/AEM.70.2.814-821.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.

Effect of Environmental Factors on the Relationship between Concentrations of Coprostanol and Fecal Indicator Bacteria in Tropical (Mekong Delta) and Temperate (Tokyo) Freshwaters

Faculty of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan,¹ College of Agriculture, Can Tho University, Can Tho City, Can Tho Province, Vietnam²

Received 29 September 2003/ Accepted 30 October 2003

A reliable assessment of microbial indicators of fecal pollution (total coliform, Escherichia coli, and fecal streptococcus) is critical in tropical environments. Therefore, we investigated the relationship between concentrations of indicator bacteria and a chemical indicator, coprostanol (5ß-cholestan-3ß-ol), in tropical and temperate regions. Water samples were collected from the Mekong Delta, Vietnam, during wet and dry seasons, and from Tokyo, Japan, during summer, the aftermath of a typhoon, and winter. During the wet season in the Mekong Delta, higher bacterial densities were observed in rivers, probably due to the higher bacterial inputs from soil particles with runoff. In Tokyo, higher bacterial densities were usually observed during summer, followed by those in the typhoon aftermath and winter. A strong logarithmic correlation between the concentrations of E. coli and coprostanol was demonstrated in all surveys. Distinctive seasonal fluctuations were observed, as concentrations of coprostanol corresponding to 1,000 CFU of E. coli/100 ml were at their lowest during the wet season in the Mekong Delta and the typhoon aftermath in Tokyo (30 ng/liter), followed by the dry season in the Mekong Delta and the summer in Tokyo (100 ng/liter), and they were much higher during the winter in Tokyo (400 ng/liter). These results suggested that E. coli is a specific indicator of fecal contamination in both tropical and temperate regions but that the densities are affected by elevated water temperature and input from runoff of soil particles. The concurrent determination of E. coli and coprostanol concentrations could provide a possible approach to assessing the reliability of fecal pollution monitoring data.