Chemoselective Nitro Group Reduction and Reductive Dechlorination Initiate Degradation of 2-Chloro-5-Nitrophenol by Ralstonia eutropha JMP134

Abstract

Ralstonia eutropha JMP134 utilizes 2-chloro-5-nitrophenol as a sole source of nitrogen, carbon, and energy. The initial steps for degradation of 2-chloro-5-nitrophenol are analogous to those of 3-nitrophenol degradation in R. eutropha JMP134. 2-Chloro-5-nitrophenol is initially reduced to 2-chloro-5-hydroxylaminophenol, which is subject to an enzymatic Bamberger rearrangement yielding 2-amino-5-chlorohydroquinone. The chlorine of 2-amino-5-chlorohydroquinone is removed by a reductive mechanism, and aminohydroquinone is formed. 2-Chloro-5-nitrophenol and 3-nitrophenol induce the expression of 3-nitrophenol nitroreductase, of 3-hydroxylaminophenol mutase, and of the dechlorinating activity. 3-Nitrophenol nitroreductase catalyzes chemoselective reduction of aromatic nitro groups to hydroxylamino groups in the presence of NADPH. 3-Nitrophenol nitroreductase is active with a variety of mono-, di-, and trinitroaromatic compounds, demonstrating a relaxed substrate specificity of the enzyme. Nitrosobenzene serves as a substrate for the enzyme and is converted faster than nitrobenzene.

Characterization of a Nitroreductase with Selective Nitroreduction Properties in the Food and Intestinal Lactic Acid Bacterium Lactobacillus plantarum WCFS1

“…The enzyme was not able to reduce the hydroxylamine further to p-aminobenzoate. This behaviour agrees well with other microbial nitroreductases (39) that afford nitrosoaromatic as a limiting step that quickly react to give hydroxylamine products (29,49).…”

Change of bacterial communities in sediments along Songhua River in Northeastern China after a nitrobenzene pollution event

“…The most notable characteristics for clones of contaminated and downstream sites B–E were the predominance of Betaproteobacteria and Firmicutes . Until now, many reported nitrobenzene‐degrading bacteria are Comamonadaceae of the class Betaproteobacteria (Groenewegen & de Bont, 1992; Schenzle et al , 1999; Zhao & Ward, 1999). The clones belonging to Comamonadaceae were indeed similar to the reported nitroaromatic compounds‐utilizing strains.…”

Genetic and Biochemical Characterization of 2-Chloro-5-Nitrophenol Degradation in a Newly Isolated Bacterium, Cupriavidus sp. Strain CNP-8

“…The phylogenetic relationships of the 16S rRNA gene sequences of strain CNP-8 and other representative Cupriavidus strains are shown in Figure 1B . Before this study, there is only one bacterium, Cupriavidus pinatubonensis JMP134 (Schenzle et al, 1999b ), was reported to be able to degrade 2C5NP.…”

“…The aromatics with nitro group at meta position are considered to be more resistant to microbial attack than the compounds that have nitro group at para position (Arora et al, 2012b ). To date, only one bacterium, Cupriavidus pinatubonensis JMP134 (formerly Cupriavidus necator JMP134 or Ralstonia eutropha JMP134), was reported to degrade 2C5NP (Schenzle et al, 1999b ), and the molecular mechanism of 2C5NP degradation remains unknown.…”