Bacteria of an anaerobic 1,2-dichloropropane-dechlorinating mixed culture are phylogenetically related to those of other anaerobic dechlorinating consortia

A 16S-rDNA-based molecular study was performed to determine the bacterial d iversity of an anaerobic, 1,2-dichloropropane-dechlorinating bioreactor con sortium derived from sediment of the River Saale, Germany. Total community DNA was extracted and bacterial 16S rRNA genes were subsequently amplified using conserved primers. A clone library wits constructed and analysed by s equencing the 16S rDNA inserts of randomly chosen clones followed by dot bl ot hybridization with labelled polynucleotide probes. The phylogenetic anal ysis revealed significant sequence similarities of several as yet unculture d bacterial species in the bioreactor to those found in other reductively d echlorinating freshwater consortia. In contrast, no close relationship was obtained with as yet uncultured bacteria found in reductively dechlorinatin g consortia derived from marine habitats. One rDNA clone showed >97% sequen ce similarity to Dehalobacter species, known for reductive dechlorination o f tri- and tetrachloroethene. These results suggest that reductive dechlori nation in microbial freshwater habitats depends upon a specific bacterial c ommunity structure.