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

Abstract

Compound 2-chloro-5-nitrophenol (2C5NP) is a typical chlorinated nitroaromatic pollutant. To date, the bacteria with the ability to degrade 2C5NP are rare, and the molecular mechanism of 2C5NP degradation remains unknown. In this study, Cupriavidus sp. strain CNP-8 utilizing 2-chloro-5-nitrophenol (2C5NP) and meta-nitrophenol (MNP) via partial reductive pathways was isolated from pesticide-contaminated soil. Biodegradation kinetic analysis indicated that 2C5NP degradation by this strain was concentration dependent, with a maximum specific degradation rate of 21.2 ± 2.3 μM h−1. Transcriptional analysis showed that the mnp genes are up-regulated in both 2C5NP- and MNP-induced strain CNP-8. Two Mnp proteins were purified to homogeneity by Ni-NTA affinity chromatography. In addition to catalyzing the reduction of MNP, MnpA, a NADPH-dependent nitroreductase, also catalyzes the partial reduction of 2C5NP to 2-chloro-5-hydroxylaminophenol via 2-chloro-5-nitrosophenol, which was firstly identified as an intermediate of 2C5NP catabolism. MnpC, an aminohydroquinone dioxygenase, is likely responsible for the ring-cleavage reaction of 2C5NP degradation. Gene knockout and complementation indicated that mnpA is necessary for both 2C5NP and MNP catabolism. To our knowledge, strain CNP-8 is the second 2C5NP-utilizing bacterium, and this is the first report of the molecular mechanism of microbial 2C5NP degradation.

Biodegradation of 2-chloro-4-nitrophenol via a hydroxyquinol pathway by a Gram-negative bacterium, Cupriavidus sp. strain CNP-8

“…Strain CNP-8 was recently isolated from the pesticide-contaminated soil collected from Yantai, Shandong, China (Min et al 2017b ). It has been deposited in the China Center for Type Culture Collection (Wuhan) with accession number CCTCC M 2017546.…”

Biodegradation of 2,6-dibromo-4-nitrophenol by Cupriavidus sp. strain CNP-8: Kinetics, pathway, genetic and biochemical characterization

“…Cupriavidus sp. strain CNP-8 isolated previously [22] has been deposited in the China Center for Type Culture Collection (accession number: M 2017546). Escherichia coli strains were grown in lysogeny broth (LB) (tryptone: 10 g L −1 , NaCl: 10 g L −1 and yeast extract: 5 g L −1 ) at 37°C.…”

“…Brominated nitrophenols (BNPs) are structurally analogues of chlorinated nitrophenols (CNPs) which are the most common halogenated nitrophenols. To data, many microorganisms have evolved their capacity to degrade various isomers of mono-chlorinated nitrophenols (MCNPs) including 2-chloro-4-nitrophenol (2C4NP) [16][17][18][19], 4-chloro-2-nitrophenol [20], 4-chloro-3-nitrophenol [21] and 2-chloro-5-nitrophenol [22]. Noteworthily, the relative position of nitro and chloro significantly affected MCNPs degradation by microorganisms because of electron delocalization on the aromatic ring.…”

Microbial degradation kinetics and molecular mechanism of 2,6-dichloro-4-nitrophenol by a Cupriavidus strain

“…Up to now, studies on microbial degradation of CNPs by pure culture bacteria were mainly focused on monochlorinated nitrophenols. Many bacteria with the ability to degrade monochlorinated nitrophenols such as 2-chloro-4-nitrophenol (2C4NP) (Ghosh et al, 2010;Arora and Jain, 2011;Pandey et al, 2011;Arora and Jain, 2012;Min et al, 2014;Min et al, 2016;Tiwari et al, 2017), 2-chloro-5-nitrophenol (2C5NP) (Schenzle et al, 1999;Min et al, 2017b), 4-chloro-2-nitrophenol (Arora et al, 2012a,b) or 4-chloro-3-nitrophenol (Arora et al, 2014) have been isolated. Due to the different substitutional position of chloro and nitro groups on the aromatic ring, these bacteria exhibited various catabolic pathways against different isomers (Arora et al, 2018).…”

“…Previously, Cupriavidus sp. strain CNP-8 isolated by us has been reported to degrade several nitrophenols including meta-nitrophenol (MNP) and 2C5NP (Min et al, 2017b), 2C4NP (Min et al, 2018) and 2,6dibromo-4-nitrophenol (2,6-DBNP) (Min et al, 2019). Moreover, it degraded (halogenated)-meta-nitrophenol (such as MNP and 2C5NP) via the partial reductive pathways, whereas degraded halogenated para-nitrophenols (such as 2C4NP and 2,6-DBNP) via the oxidative pathways.…”