16S rRNA Gene-Based Detection of Tetrachloroethene-DechlorinatingDesulfuromonasandDehalococcoidesSpecies

Abstract

Members of the genera Desulfuromonas andDehalococcoides reductively dechlorinate tetrachloroethene (PCE) and trichloroethene. Two primer pairs specific to hypervariable regions of the 16S rRNA genes of the Dehalococcoides group (comprising Dehalococcoides ethenogenes andDehalococcoides sp. strain FL2) and the acetate-oxidizing, PCE-dechlorinating Desulfuromonas group (comprisingDesulfuromonas sp. strain BB1 and Desulfuromonas chloroethenica) were designed. The detection threshold of a nested PCR approach using universal bacterial primers followed by a second PCR with the Desulfuromonas dechlorinator-targeted primer pair was 1 × 10³ BB1 cells added per gram (wet weight) of sandy aquifer material. Total community DNA isolated from sediments of three Michigan rivers and six different chloroethene-contaminated aquifer samples was used as template in nested PCR. All river sediment samples yielded positive signals with the BB1- and the Dehalococcoides-targeted primers. One chloroethene-contaminated aquifer tested positive with theDehalococcoides-targeted primers, and another contaminated aquifer tested positive with the Desulfuromonasdechlorinator-targeted primer pair. Restriction fragment analysis of the amplicons could discriminate strain BB1 from other knownDesulfuromonas species. Microcosm studies confirmed the presence of PCE-dechlorinating, acetate-oxidizingDesulfuromonas and hydrogenotrophicDehalococcoides species in samples yielding positive PCR signals with the specific primers.