Abstract
To understand the extent of natural adaptation to chemical exposure within a microbial consortium, we scrutinized the dynamic relationship between the microbial diversity and biodegradation capacity of octylphenol polyethoxylates (OPEOn), as representative alkylphenol polyethoxylates (APEOn), using enrichment cultures of various sediments from the Iwata River system. To address the potential of microbes in river sediments to transform a surfactant into endocrine-disrupting chemicals, the ability of the microbes to degrade OPEOn in six different sediment samples was assessed by enrichment culture. In addition, 16S rRNA gene-based denaturing gradient gel electrophoresis (DGGE) analysis was conducted to elucidate the microbial communities before and after enrichment of OPEOn-degrading microbes. Functional gene (adh1) copies were also enumerated to estimate the potential of OPEOn degradation in the six sediment samples. Moreover, microbial communities in three of the six sediment samples were characterized by 16S rRNA-based clone analysis. OPEOn-degrading activity was determined to be present in five of the six enrichment cultures; however, no predominant species could be found by clone analysis. DGGE analysis revealed that the genus Pseudomonas, which contributes to the degradation of OPEOn, was one of the major populations in the enrichment cultures. The adh1 gene enumeration was shown to be relatively high when river flow was relatively slow. These results suggest that potential OPEOn degraders are widely distributed in Iwata River with differences in their history of chemical exposure.
