• Journal of Microbiology and Biotechnology
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• v.26 no.1
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• pp.120-129
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• 2016

An industrial complex in Wonju, contaminated with trichloroethene (TCE), was one of the most problematic sites in Korea. Despite repeated remedial trials for decades, chlorinated ethenes remained as sources of down-gradient groundwater contamination. Recent efforts were being made to remove the contaminants of the area, but knowledge of the indigenous microbial communities and their dechlorination abilities were unknown. Thus, the objectives of the present study were (i) to evaluate the dechlorination abilities of indigenous microbes at the contaminated site, (ii) to characterize which microbes and reductive dehalogenase genes were responsible for the dechlorination reactions, and (iii) to develop a PCE-to-ethene dechlorinating microbial consortium. An enrichment culture that dechlorinates PCE to ethene was obtained from Wonju stream, nearby a trichloroethene (TCE)-contaminated industrial complex. The community profiling revealed that known organohalide-respiring microbes, such as Geobacter, Desulfuromonas, and Dehalococcoides grew during the incubation with chlorinated ethenes. Although Chloroflexi populations (i.e., Longilinea and Bellilinea) were the most enriched in the sediment microcosms, those were not found in the transfer cultures. Based upon the results from pyrosequencing of 16S rRNA gene amplicons and qPCR using TaqMan chemistry, close relatives of Dehalococcoides mccartyi strains FL2 and GT seemed to be dominant and responsible for the complete detoxification of chlorinated ethenes in the transfer cultures. This study also demonstrated that the contaminated site harbors indigenous microbes that can convert PCE to ethene, and the developed consortium can be an important resource for future bioremediation efforts.

• Journal of Life Science
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• v.26 no.6
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• pp.711-720
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• 2016

To determine the degree of common genes and the phylogenetic relationships among genome-sequenced 680 prokaryotes, the similarities among 4,631 clusters of orthologous groups of protein (COGs)’ presence/ absence and gene content trees were analyzed. The number of COGs was in the range of 103–2,199 (mean 1377.1) among 680 prokaryotes. Candidatus Nasuia deltocephalinicola str. NAS-ALF, an obligate symbiont with insects, showed the minimum COG, while Pseudomonas aeruginosa PAO1, an opportunistic pathogen, represented the maximum COG. The similarities between two prokaryotes were 49.30–99.78 % (mean 72.65%). Methanocaldococcus jannaschii DSM 2661 (hyperthermophilic and autotrophic, Euryarchaeota phylum) and Mesorhizobium loti MAFF303099 (mesophilic and symbiotic, alpha-Proteobacteria class) had the minimum amount of similarities. As gene content may represent the potential for an organism to adapt to each habitat, this may represent the history of prokaryotic evolution or the range of prokaryotic habitats at present on earth. COG content trees represented the following. First, two members of Chloroflexi phylum (Dehalogenimonas lykanthroporepellens BL-DC-9 and Dehalococcoides mccartyi 195) showed a greater relationship with Archaea than other Eubacteria. Second, members of the same phylum or class in the 16S rRNA gene were separated in the COG content tree. Finally, delta- and epsilon-Proteobacteria were in different lineages with other Proteobacteria classes in neighbor-joining (NJ) and maximum likelihood (ML) trees. The results of this study would be valuable to identifying the origins of organisms, functional relationships, and useful genes.