Biodegradation of chlorpropham and its major products by Bacillus licheniformis NKC-1

Abstract

Chlorpropham [isopropyl N-(3-chlorophenyl) carbamate] (CIPC), an important phenyl carbamate herbicide, has been used as a plant growth regulator and potato sprout suppressant (Solanum tuberosum L) during long-term storage. A bacterium capable of utilizing the residual herbicide CIPC as a sole source of carbon and energy was isolated from herbicide-contaminated soil samples employing selective enrichment method. The isolated bacterial strain was identified as Bacillus licheniformis NKC-1 on the basis of its morphological, cultural, biochemical characteristics and also by phylogenetic analysis based on 16S rRNA gene sequences. The organism degraded CIPC through its initial hydrolysis by CIPC hydrolase enzyme to yield 3-chloroaniline (3-CA) as a major metabolic product. An inducible 3-CA dioxygenase not only catalyzes the incorporation of molecular oxygen but also removes the amino group by the deamination yielding a monochlorinated catechol. Further, degradation of 4-chlorocatechol proceeded via ortho- ring cleavage through the maleylacetate process. 3-Chloroaniline and 4-chlorocatechol are the intermediates in the CIPC degradation which suggested that dechlorination had occurred after the aromatic ring cleavage. The presence of these metabolites has been confirmed by using ultra-violet (UV), high-performance liquid chromatography (HPLC), thin layer chromatography (TLC), Fourier transmission-infrared (FT-IR), proton nuclear magnetic resonance (H NMR) and gas chromatography-mass (GC-MS) spectral analysis. Enzyme activities of CIPC hydrolase, 3-CA dioxygenase and chlorocatechol 1, 2-dioxygenase were detected in the cell-free-extract of the CIPC culture and are induced by cells of NKC-1 strain. These results demonstrate the biodegradation pathways of herbicide CIPC and promote the potential use of NKC-1 strain to bioremediate CIPC-contaminated environment with subsequent release of ammonia, chloride ions and carbon dioxide.

Comparative genome analysis and mining of secondary metabolites of <i>Paenibacillus polymyxa</i>

“…The genome A18, which encodes the gene involved in the response to X2-CBM3, was selected as bait for mining the genome of P. polymyxa (Pasari et al, 2017). Bacillus can secrete CIPC hydrolase, 3-CA dioxygenase and chlorocatechol 1, 2-dioxygenase, which can degrade the herbicide phenyl carbamate (CIPC) and reduce herbicide damage to animals and plants (Pujar et al, 2018). Paenibacillus polymyxa natto kinase (NK), trehalose-6-phosphoric acid hydrolase (TreA), glycine oxidase (BliGO), gamma glutamyl transpeptidase (BlGGT), methyl pectin enzyme (BliPME), meso-2,3-butanediol dehydrogenase (BlBDH), glucose transferase (YjiC) and tagatose sugar-1-phosphokinase (TagK) were included in our genome mining work.…”

Wide substrate range for a candidate bioremediation enzyme isolated from Nocardioides sp. strain SG-4 G

“…Thus, the strain and enzyme have activity against carboxylester, carbamate, and amide linkages. Importantly, the hydrolysis of the phthalates greatly reduces their toxicity, and the hydrolysis of the carbendazim, anilides, and chlorpropham eliminates their respective fungicidal and herbicidal activities (Jonsson and Baun 2003 , Pandey et al 2009 , Carvalho et al 2010 , Pujar et al 2018 ). Given the ubiquity of the phthalates in various industries and the large numbers of benzimidazole fungicides and anilide and carbamate herbicides used in agriculture, strain SG-4 G and MheI are potentially versatile bioremediant resources.…”

Efficient Remediation of p-chloroaniline Contaminated Soil by Activated Persulfate Using Ball Milling Nanosized Zero Valent Iron/Biochar Composite: Performance and Mechanisms

“…PCA is a kind of persistent organic pollutants (POPs), which have environmental toxicity and will accumulate in the environment. A series of serious injuries to the blood system and nervous system (LD 50 orally in rats: 0.31 g kg −1 ) were observed when humans were exposed to PCA [3]. Due to its environmental toxicity, adverse impacts on human health, and persistence, PCA has been listed as a priority pollutant by the US Environmental Protection Agency (EPA) and EU legislation [4].…”