Isolation and Characterization of Desulfovibrio dechloracetivorans sp. nov., a Marine Dechlorinating Bacterium Growing by Coupling the Oxidation of Acetate to the Reductive Dechlorination of 2-Chlorophenol

Abstract

Strain SF3, a gram-negative, anaerobic, motile, short curved rod that grows by coupling the reductive dechlorination of 2-chlorophenol (2-CP) to the oxidation of acetate, was isolated from San Francisco Bay sediment. Strain SF3 grew at concentrations of NaCl ranging from 0.16 to 2.5%, but concentrations of KCl above 0.32% inhibited growth. The isolate used acetate, fumarate, lactate, propionate, pyruvate, alanine, and ethanol as electron donors for growth coupled to reductive dechlorination. Among the halogenated aromatic compounds tested, only the ortho position of chlorophenols was reductively dechlorinated, and additional chlorines at other positions blocked ortho dechlorination. Sulfate, sulfite, thiosulfate, and nitrate were also used as electron acceptors for growth. The optimal temperature for growth was 30°C, and no growth or dechlorination activity was observed at 37°C. Growth by reductive dechlorination was revealed by a growth yield of about 1 g of protein per mol of 2-CP dechlorinated, and about 2.7 g of protein per mole of 2,6-dichlorophenol dechlorinated. The physiological features and 16S ribosomal DNA sequence suggest that the organism is a novel species of the genus Desulfovibrio and which we have designated Desulfovibrio dechloracetivorans. The unusual physiological feature of this strain is that it uses acetate as an electron donor and carbon source for growth with 2-CP but not with sulfate.Substantial amounts of halogenated aromatic compounds have been released to the environment and many of them have accumulated in groundwater and sediments (11,14,24,26). Many of these compounds are resistant to aerobic microbial metabolism often because the chlorine substitution blocks oxygenase attack. Fortunately, many halogenated compounds can be dehalogenated by anaerobic microorganisms. Several bacteria capable of dehalogenating halogenated aromatic compounds have been isolated and characterized (2,3,4,5,18,25,27,28,29). One previous isolate has been described which reductively dechlorinates 2-chlorophenol (2-CP) to phenol (5). This organism was isolated from freshwater sediment and is unique for dechlorinators in that it could also grow as a microaerophile, although it did not dechlorinate under this condition. Bacteria, such as this one, which use the dehalogenation reaction as their sole electron acceptor for energy generation and growth are termed halorespirers (25) or dehalorespirers (11).To date, much of the dehalogenation research has been directed toward understanding the fate and behavior of halogenated pollutants in freshwater sediments, soils, and sludges. Comparatively little is known about the fates of these pollutants or dehalogenating organisms from the marine environment despite the fact that marine biota produce a remarkable array of halogenated compounds (12). For example, studies by King (15) indicate that 2,4-dibromophenol occurred at concentrations of up to several hundred micromolar in hemichordate burrow walls and that this chemical was dehalogenated in these sediments under anae...

Desulfoluna spongiiphila sp. nov., a dehalogenating bacterium in the Desulfobacteraceae from the marine sponge Aplysina aerophoba

“…Desulfovibrio were isolated by using halophenols as electron acceptors (Boyle et al, 1999, Sun et al, 2000. Sun et al (2000) isolated a halobenzoate-dehalogenating Desulfomonile limimaris strain from marine sediments.…”

“…Desulfovibrio were isolated by using halophenols as electron acceptors (Boyle et al, 1999, Sun et al, 2000. Sun et al (2000) isolated a halobenzoate-dehalogenating Desulfomonile limimaris strain from marine sediments. Propionigenium maris, isolated from bromophenol-producing worms, is capable of debrominating 2,4,6-tribromophenol to 4-bromophenol (Steward et al, 1995;Watson et al, 2000).…”

Desulfomonile limimaris sp. nov., an anaerobic dehalogenating bacterium from marine sediments.

“…A sulfate-free, anaerobic, synthetic sea-water medium (Sun et al, 2000) with 2n5% (w\v) NaCl was used to favour dechlorinators rather than sulfate-reducers. Shallow marine sediments were collected from Gulf Breeze (north-west Florida, USA), Big Pine Key (south Florida, USA), King Salmon (Alaska, USA), San Francisco Bay (California, USA), Pearl Harbour and Kanehoe Bay (Hawaii, USA), Johnston Island (Pacific Ocean) and Mayaguez (Puerto Rico).…”

“…Whilst these organisms were very difficult and tedious to isolate in the initial studies, several have now been isolated and characterized (Shelton & Tiedje, 1984 ;Madsen & Licht, 1992 ;Cole et al, 1994 ;Utkin et al, 1994 ;Steward et al, 1995 ;Bouchard et al, 1996 ;Christiansen & Ahring, 1996 ;Sanford et al, 1996 ;Boyle et al, 1999 ;Sun et al, 2000). Desulfomonile tiedjei strain DCB-1 T , the first such strain, was isolated from sewage sludge in which 3-chlorobenzoate (3CB) was being used as the electron acceptor (Shelton & Tiedje, 1984).…”

“…The first marine dechlorinating isolate, Desulfovibrio dechloracetivorans strain SF3 T , dechlorinates 2-chlorophenol reductively to phenol and grows at concentrations of NaCl ranging from 0n16 to 2n5% (w\v) (Sun et al, 2000).…”