DEHALOBACTER RESTRICTUS GEN. NOV. AND SP. NOV., A STRICTLY ANAEROBIC BACTERIUM THAT REDUCTIVELY DECHLORINATES TETRACHLOROETHENE AND TRICHLOROETHENE IN AN ANAEROBIC RESPIRATION

The highly enriched anaerobic bacterium that couples the reductive dec hlorination of tetrachloroethene to growth, previously referred to as PER-K23, was obtained in pure culture and characterized. The bacterium , which does not form spores, is a small, gram-negative rod with one l ateral flagellum. It utilized only H-2 as an electron donor and tetrac hloroethene and trichloroethene as electron accepters in an anaerobic respiration process; it could not grow fermentatively. Acetate served as a carbon source in a defined medium containing iron as the sole tra ce element, the two vitamins thiamine and cyanocobalamin, and the thre e amino acids arginine, histidine, and threonine. The cells contained menaquinones and b-type cytochromes. The G+C content of the DNA was 45 .3 +/- 0.3 mol%. The cell wall consisted of type-A3 gamma peptidoglyca n with LL-diaminopimelic acid and one glycine as an interpeptide bridg e. The cells are surrounded by an S-layer, an outer membrane was absen t. Comparative sequence analysis of the 16S rRNA sequence showed that PER-K23 is related to gram-positive bacteria with a low G+C content of the DNA, Based on the cytological, physiological, and phylogenetic ch aracterization, it is proposed to affiliate the isolate to a new genus , Dehalobacter, with PER-K23 as the type strain of the new species Deh alobacter restrictus.