Degradation of trichlorophenols by Alcaligenes eutrophus JMP134

Abstract

The degradation of chlorophenols by Alcaligenes eutrophus JMP134 (pJP4) was studied. The strain grew on 2,4,6-trichlorophenol or 2,4,6-tribromophenol as the sole carbon and energy source. Complete degradation of 2,4,6-trichlorophenol was confirmed by chloride release and gas chromatography analysis of supernatants from growth cultures. The 2,3,5-, 2,3,4-, 2,3,6- and 2,4,5-isomers of trichlorophenol did not support growth. However, up to 40% of 2,4,5-trichlorophenol was mineralized during growth of A. eutrophus on chemostats fed with either phenol (0.4 mM) or 2,4,6-trichlorophenol (0.4 mM) plus 2,4,5-trichlorophenol (0.1 mM). Growth on 2,4,6-trihalophenols was also observed in A. eutrophus JMP222, the strain lacking pJP4, suggesting that this new degradative ability reported for A. eutrophus is not related to pJP4 encoded catabolic functions.

Genetic and Biochemical Characterization of a 2,4,6-Trichlorophenol Degradation Pathway in Ralstonia eutropha JMP134

“…strain C964 (6). Several 2,4,6-TCP-degrading bacteria have been reported (1,2,6,9,10,25,30,42,45). Recently, Clement et al (10) have shown that Ralstonia eutropha JMP134 and JMP222 (which does not harbor the 2,4-dichlorophenoxyacetic acid-degrading plasmid pJP4) grow on 2,4,6-TCP as the sole carbon source.…”

“…Several 2,4,6-TCP-degrading bacteria have been reported (1,2,6,9,10,25,30,42,45). Recently, Clement et al (10) have shown that Ralstonia eutropha JMP134 and JMP222 (which does not harbor the 2,4-dichlorophenoxyacetic acid-degrading plasmid pJP4) grow on 2,4,6-TCP as the sole carbon source. The reported cell yields for JMP134 and JMP222 growing on only 2,4,6-TCP are extremely low, and the culture's turbidity at 660 nm reaches a maximum of 0.043 after 5 days of incubation (10).…”

“…Recently, Clement et al (10) have shown that Ralstonia eutropha JMP134 and JMP222 (which does not harbor the 2,4-dichlorophenoxyacetic acid-degrading plasmid pJP4) grow on 2,4,6-TCP as the sole carbon source. The reported cell yields for JMP134 and JMP222 growing on only 2,4,6-TCP are extremely low, and the culture's turbidity at 660 nm reaches a maximum of 0.043 after 5 days of incubation (10). The detection of 2,6-dichloro-p-hydroquinone (2,6-DiCH) during 2,4,6-TCP degradation by JMP134 whole cells and the identification of 6-chlorohydroxyquinol (6-CHQ) 1,2-dioxygenase activities in JMP134 cell extracts have led to a hypothesis that 2,4,6-TCP is degraded via 2,6-DiCH to 6-CHQ, which is subject to ring cleavage to 2-chloromaleylacetate (2-CMA) (37).…”

Biodegradation, Biotransformation, and Biocatalysis (B3)

“…In particular, the contribution of tfdCI was critical to prevent the accumulation of the toxic metabolite chlorocatechol. Both JMP134 (pJP4) and its cured derivative, JMP222, are able to grow on 2,4,6-trichlorophenol (TCP), suggesting that that pathway for TCP degradation is chromosomally encoded (16). However, while JMP222 can only grow with concentrations of TCP of up to 0.2 mM, JMP134(pJP4) can easily tolerate up to 0.5 mM TCP.…”

Engineering bacterial strains through the chromosomal insertion of the chlorocatechol catabolism tfdICDEF gene cluster, to improve degradation of typical bleached Kraft pulp mill effluent pollutants

“…These compounds can be accumulated or, otherwise, further metabolised through the ortho, modified ring-cleavage pathway . One extensively studied example of an efficient chloroaromatic degrading bacteria that use such a chlorocatechol degradation pathway is Ralstonia eutropha JMP134 (pJP4), a strain able to grow on 2,4-dichlorophenoxyacetate (2,4-D), and 3-chlorobenzoate (3-CB), as well as other chloroaromatics (Don and Pemberton, 1981;Pieper et al 1988;Clément et al 1995). Most of its catabolic abilities are encoded on the tfd genes from the plasmid pJP4 (Figure 1a).…”