Influence of Different Electron Donors and Acceptors on Dehalorespiration of Tetrachloroethene by Desulfitobacterium frappieri TCE1

Abstract

Strain TCE1, a strictly anaerobic bacterium that can grow by reductive dechlorination of tetrachloroethene (PCE) and trichloroethene (TCE), was isolated by selective enrichment from a PCE-dechlorinating chemostat mixed culture. Strain TCE1 is a gram-positive, motile, curved rod-shaped organism that is 2 to 4 by 0.6 to 0.8 μm and has approximately six lateral flagella. The pH and temperature optima for growth are 7.2 and 35°C, respectively. On the basis of a comparative 16S rRNA sequence analysis, this bacterium was identified as a new strain of Desulfitobacterium frappieri, because it exhibited 99.7% relatedness to the D. frappieri type strain, strain PCP-1. Growth with H2, formate,l-lactate, butyrate, crotonate, or ethanol as the electron donor depends on the availability of an external electron acceptor. Pyruvate and serine can also be used fermentatively. Electron donors (except formate and H2) are oxidized to acetate and CO2. When l-lactate is the growth substrate, strain TCE1 can use the following electron acceptors: PCE and TCE (to produce cis-1,2-dichloroethene), sulfite and thiosulfate (to produce sulfide), nitrate (to produce nitrite), and fumarate (to produce succinate). Strain TCE1 is not able to reductively dechlorinate 3-chloro-4-hydroxyphenylacetate. The growth yields of the newly isolated bacterium when PCE is the electron acceptor are similar to those obtained for other dehalorespiring anaerobes (e.g.,Desulfitobacterium sp. strain PCE1 andDesulfitobacterium hafniense) and the maximum specific reductive dechlorination rates are 4 to 16 times higher (up to 1.4 μmol of chloride released · min−1 · mg of protein−1). Dechlorination of PCE and TCE is an inducible process. In PCE-limited chemostat cultures of strain TCE1, dechlorination is strongly inhibited by sulfite but not by other alternative electron acceptors, such as fumarate or nitrate.

Coexistence of a sulphate‐reducing Desulfovibrio species and the dehalorespiring Desulfitobacterium frappieri TCE1 in defined chemostat cultures grown with various combinations of sulphate and tetrachloroethene

“…strain PCE-S (Miller et al, 1997;Townsend and Suflita, 1997;Gerritse et al, 1999), whereas nitrate and fumarate did not appear to have a negative influence on dehalogenation of chlorinated compounds by Desulfomonile tiedjei and Db. frappieri TCE1 (Townsend and Suflita, 1997;Gerritse et al, 1999). The impact of sulphate (as an alternative electron acceptor) on microbially mediated dehalogenation has led to different conclusions in the literature.…”

“…Strain SULF1, tentatively assigned to the genus Desulfovibrio, was also isolated from the aforementioned anoxic PCE-dechlorinating mixed culture, and, therefore, originated from the same polluted soil obtained from a site of a former chemical laundry in Breda (The Netherlands). Both strains were isolated through anoxic dilution series, which were made after 6 months of enrichment (Gerritse et al, 1999).…”

“…sp. strain PCE1) (Gerritse et al, 1999;Holliger et al, 1999). Much like various other dehalorespiring bacteria (for example Desulfomonile tiedjei, Desulfuromonas chloroethenica, Dehalobacter restrictus, Dehalospirillum multivorans, Dehalococcoides ethenogenes) (Holliger et al, 1999), the Desulfitobacteria have attracted a great deal of interest over the past few years as they have considerable potential for the degradation of polyhalogenated pollutants such as tetrachloroethene (PCE), trichloroethene (TCE), carbon tetrachloride, and pentachlorophenol (PCP) in soils and groundwater (Meyer et al, 1993;Dolfing and Beurskens, 1995;Bouchard et al, 1996;Lee et al, 1997;Spuij et al, 1997;DeWeerd et al, 1998;Gerritse et al, 1998).…”

“…On the other hand, sulphate has been described to have no influence on dehalogenation mediated by dehalogenating bacteria or by sulphate-reducing bacteria which use this compound as their terminal electron acceptor (e.g. Bagley and Gossett, 1990;Drzyzga et al, 1994;Gerritse et al, 1999). In this context, Desulfomonile tiedjei was the first sulphate reducer that was shown to couple reductive dechlorination of 3-chlorobenzoate to growth (Mohn and Tiedje, 1992;Townsend and Suflita, 1997).…”

An unusual tandem‐domain rhodanese harbouring two active sites identified in Desulfitobacterium hafniense

“…The expression of PhsE appeared to be influenced by the presence and nature of the sulfur compounds with the most direct effect being observed with addition of sulfide. A delayed induction of PhsE expression could also be attributed to thiosulfate and sulfite, which could be explained by the production of sulfide upon the physiological reduction of these substrates by Desulfitobacterium [39]. The impact of sulfide on microorganisms remains unclear.…”