PARENT SESSION
PW7 - Biotransformation / Metabolisms / Degradation
Wednesday, 20 November 2002
8:00 AM to 6:30 PM
Exhibit Hall

(P794) Predicting fate of chemicals based on a quantity of degrading microorganisms determined by real-time PCR.

Yamane, Hidefumi^*,1, Nishiyama, Naohiro¹, Suzuki, Hiroyuki¹, Nasu, Masao², ¹ Safety and Microbial Control Research Center, Kao Corporation, Haga, Tochigi² Graduate School of Pharmaceutical Sciences, Osaka University, Suita, Osaka

ABSTRACT- Microbial degradation is important factor to predict fate of chemical substances in aquatic environment. Although it seems that degradation rate of chemical substances in aquatic environment depend on a quantity of degrading microorganisms, there is few report on their relationship. In this study, we developed a rapid and specific enumeration method for polyvinyl alcohol (PVA), as a model chemical substance, degrading bacteria by means of real-time PCR and investigated relationship between the cell number and degradation rate in environmental samples. PVA-degrading bacteria, Sphingomonas capsulata UP-3 was isolated from surface water of Tagawa River, Utsunomiya City, Tochigi, Japan. The PCR primers and probe for real-time PCR were designed based on the polyvinyl alcohol dehydrogenase gene (pvaA) fragment of UP-3 strain. Bacterial DNA for PCR amplification was extracted by freeze-thaw method. The linearity and detection limit of this assay showed 10⁰ to 10⁷ cells (R²=0.999) and 200 cells/L in artificial river water, respectively. Cell-addition experiment gave predicted results, suggesting that this assay provides an accurate measure of PVA-degrading bacteria abundance in environmental samples. Degradation rate of PVA was determined according to OECD test guideline 301A (River die-away test). In the assay of environmental samples, PVA-degrading bacteria was detected from three river water samples. The cell number range between 10³ and 10⁶ cells/L. The correlation between the cell number and degradation rate was extremely high (R²=0.999). These results indicate that a quantity of degrading microorganisms might be index to predict fate of chemical substances in aquatic environment.

Key words: Biodegradation, Degrading microorganisms, Environmental fate, Quantitative PCR