Isolation and Characterization of Desulfitobacterium frappieri sp. nov., an Anaerobic Bacterium Which Reductively Dechlorinates Pentachlorophenol to 3-Chlorophenol

Abstract

An anaerobic bacterium, strain PCP-lT (T = type strain), which dechlorinates pentachlorophenol (PCP) to 3-chlorophenol, was isolated from a methanogenic consortium. This organism is a spore-forming rod-shaped bacterium that is nonmotile, asaccharolytic, and Gram stain negative but Gram type positive as determined by electron microscopic observations. Inorganic electron acceptors, such as sulfite, thiosulfate, and nitrate (but not sulfate), stimulate growth in the presence of pyruvate and yeast extract. The optimum pH and optimum temperature for growth are 7.5 and 38"C, respectively. The dechlorination pathway is: PCP -+ 2,3,4,5-tetrachlorophenol + 3,4,5-trichlorophenoI + 3,5-dichlorophenol + 3-chlorophenol. This bacterium dechlorinates several different chlorophenols at ortho, meta, and para positions; exceptions to this are 2,3-dichlorophenol, 2,5-dichlorophenol, 3,4-dichlorophenol, and the monochlorophenols. The time course of PCP dechlorination suggests that two enzyme systems are involved in dehalogenation in strain PCP-lT. One system is inducible for ortho dechlorination, and the second system is inducible for meta and para dechlorinations. A 16s rRNA analysis revealed that strain PCP-lT exhibits 95% homology with Desu@tobacterium dehalogenans JW/IU-DCl, an anaerobic bacterium which can dehalogenate chlorophenols only in ortho positions. These results suggest that strain PCP-lT is a member of a new species and belongs to the recently proposed genus DesuZjhbacteriurn. Strain PCP-lT differs from D. dehalogenans JW/IU-DCl by its broader range of chlorophenol dechlorination. Strain PCP-1 is the type strain of the new species, DesuEftobacterium frappieri.Only a few anaerobic bacteria that can reductively dechlorinate chlorophenols have been isolated in pure culture. Desulfornonile tiedjei DCB-1 is the best-described dechlorinating anaerobic bacterium to date (7). This organism is a strictly anaerobic, gram-negative, sulfate-reducing bacterium that obtains energy for growth from reductive dehalogenation of 3-chlorobenzoate with formate as an electron donor (8, 19). In the presence of 3-chlorobenzoate, this strain can also dechlorinate rneta-substituted halobenzoates (9, 15) and chlorophenols (18). Madsen and Licht (16) isolated a Clostridium-like microorganism, strain DCB-2, that can dechlorinate 2,4,6-chlorophenol to 2,4-chlorophenol and finally to 4-chlorophenol; removal of rneta-substituted chlorine has been observed only with 3,s-chlorophenol. DesulJitobacteriurn dehalogenans JWf IU-DC1, a gram-positive anaerobic bacterium, can dehalogenate a wide range of chlorophenols, including pentachloropheno1 (PCP) and related compounds, at the ortho position (22, 23). This strain can use various alternative electron acceptors, including sulfur, sulfoxy anions (except sulfate), nitrate, and fumarate. Recently, a novel, gram-negative, facultatively anaerobic, rod-shaped bacterium which can grow anaerobically via reductive dehalogenation of 2-chlorophenol was isolated (5). This microaerophilic bacterium is a member of th...

Dehalogenation of the Herbicides Bromoxynil (3,5-Dibromo-4-Hydroxybenzonitrile) and Ioxynil (3,5-Diiodino-4-Hydroxybenzonitrile) by Desulfitobacterium chlororespirans

“…Additionally, D. chlororespirans can form spores; thus, its survival under unfavorable (e.g., aerobic) conditions in soil is likely. This type of bacterium, along with other dehalogenating soil microbes living in anoxic microhabitats, is poised to respond to transient anaerobic conditions (e.g., when soils flood) and metabolize halogenated herbicides like bromoxynil (4,7,14,39). Future research will focus on actual contributions of anaerobic dehalogenation activity to the metabolic fate of halogenated pesticides in the soil environment.…”

The Hydrogenase Chip: a tiling oligonucleotide DNA microarray technique for characterizing hydrogen-producing and -consuming microbes in microbial communities

“…hydrogenase genes, some showed significant differences between the probe intensities for the propionate and formate amendments. In general, genes from the Dehalococcoides strain CBDB1 genome were enriched in the propionate amendment, genes from the genome of Dehalococcoides ethenogenes strain 195 showed no significant difference between the two treatments (Utkin et al, 1994;Bouchard et al, 1996;Christiansen and Ahring, 1996;Sanford et al, 1996;Finneran et al, 2002). Notably, no hydrogen-producing fermenting microorganisms were detected in any of the samples analyzed from the soil column.…”

Biodiversity of Dehalorespiring Bacteria with Special Emphasis on Polychlorinated Biphenyl/Dioxin Dechlorinators

“…At the same time, Desulfitobacterium hafniense was described with the type strain DCB-2 T (=DSM 10664 T ) 30) , which is able to dechlorinate pentachlorophenol and 3-chloro-4-hydroxyphenylacetate but not PCE. Some other strains of Desulfitobacterium hafniense were reported to dechlorinate pentachlorophenol 22,79,122) , 2,4,6-trichlorophenol 24) , 3-chloro-4-hydroxy-phenylacetate 51,52) , and PCE 51,120) . Strain PCP-1 was isolated from a methanogenic consortium and classified originally as a new species of the genus Desulfitobacterium with the name Desulfitobacterium frappieri 22) .…”

“…Some other strains of Desulfitobacterium hafniense were reported to dechlorinate pentachlorophenol 22,79,122) , 2,4,6-trichlorophenol 24) , 3-chloro-4-hydroxy-phenylacetate 51,52) , and PCE 51,120) . Strain PCP-1 was isolated from a methanogenic consortium and classified originally as a new species of the genus Desulfitobacterium with the name Desulfitobacterium frappieri 22) . However, this organism has been reclassified as a strain of Desulfitobacte-rium hafniense 98) .…”