DESULFITOBACTERIUM SP STRAIN PCE1, AN ANAEROBIC BACTERIUM THAT CAN GROW BY REDUCTIVE DECHLORINATION OF TETRACHLOROETHENE OR ORTHO-CHLORINATED PHENOLS

A strictly anaerobic bacterium, strain PCE1, was isolated from a tetra chloroethene-dechlorinating enrichment culture. Cells of the bacterium were motile curved rods, with approximately four lateral flagella. Th ey possessed a gram-positive type of cell wall and contained cytochrom e c. Optimum growth occurred at pH 7.2-7.8 and 34-38 degrees C. The or ganism grew with L-lactate, pyruvate, butyrate, formate, succinate, or ethanol as electron donors, using either tetrachloroethene, 2-chlorop henol, 2,4,6-trichlorophenol, 3-chloro-4-hydroxy-phenylacetate, sulfit e, thiosulfate, or fumarate as electron accepters. Strain PCE1 also gr ew fermentatively with pyruvate as the sole substrate. L-Lactate and p yruvate were oxidized to acetate. Tetrachloroethene was reductively de chlorinated to trichloroethene and small amounts (< 5%) of cis-1,2-dic hloroethene and trans-1,2-dichloroethene. Chlorinated phenolic compoun ds were dechlorinated specifically at the ol-tho-position. On the basi s of 16S rRNA sequence analysis, the organism was identified as a spec ies within the genus Desulfitobacterium, which until now only containe d the chlorophenol-dechlorinating bacterium, Desulfitobacterium dehalo genans.