Microbial structure of an anaerobic bioreactor population that continuously dechlorinates 1,2-dichloropropane

The bacterial diversity of an anaerobic 1,2-dichloropropane (DCP) dechlorinating bioreactor consortium derived from river sediment has been investigated by a combined molecular approach. By using rDNA clone libraries, denaturing gradient gel electrophoresis and quantitative real-time PCR, both Dehalococcoides ethenogenes- and Dehalobacter restrictus-like 16S rDNA sequences were found within the community. Both species are known for reductive dechlorination of tetrachloroethene. Furthermore, numerous yet-uncultured members of the Green non-sulfur bacteria occurred within the consortium. The community analyses over a period of 14 months revealed a clear population shift. D. restrictus 16S rDNA was enriched significantly and became the most abundant rDNA sequence type, suggesting that Dehalobacter spp. play a key role within the reductive dechlorination of DCP in this consortium. We propose the use of this species as an indicator to monitor the transformation process within the bioreactor.