P. G. Department of Studies in Biochemistry, Karnatak University, Dharwad, Karnataka, 580 003, India.
P. G. Department of Studies in Chemistry, Karnatak University, Dharwad, Karnataka, 580 003, India.
World J Microbiol Biotechnol. 2018 Jul 6;34(8):112. doi: 10.1007/s11274-018-2494-8.
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.
氯丙酰基[异丙基 N-(3-氯苯基)氨基甲酸酯]（CIPC），一种重要的苯氨基甲酸酯类除草剂，曾被用作植物生长调节剂和马铃薯发芽抑制剂（Solanum tuberosum L），以在长期储存过程中抑制其发芽。本研究采用选择性富集方法，从受除草剂污染的土壤样品中分离出一种能够利用残留除草剂 CIPC 作为唯一碳源和能源的细菌。根据其形态学、培养特性、生化特性以及基于 16S rRNA 基因序列的系统发育分析，将分离到的细菌菌株鉴定为地衣芽孢杆菌 NKC-1。该菌通过 CIPC 水解酶的初始水解作用将 CIPC 降解为 3-氯苯胺（3-CA），作为主要代谢产物。诱导型 3-CA 双加氧酶不仅能催化分子氧的掺入，还能通过脱氨作用去除氨基，生成单氯邻苯二酚。此外，4-氯邻苯二酚通过顺式-环裂解通过马来酸乙酰酯途径进行降解。3-氯苯胺和 4-氯邻苯二酚是 CIPC 降解的中间产物，这表明在芳环裂解后发生了脱氯作用。这些代谢物的存在通过使用紫外线（UV）、高效液相色谱（HPLC）、薄层层析（TLC）、傅里叶变换红外（FT-IR）、质子核磁共振（H NMR）和气相色谱-质谱（GC-MS）光谱分析得到了证实。在 CIPC 培养物的无细胞提取物中检测到 CIPC 水解酶、3-CA 双加氧酶和邻氯邻苯二酚 1,2-双加氧酶的酶活性，并且这些酶活性可被 NKC-1 菌株的细胞诱导。这些结果表明了除草剂 CIPC 的生物降解途径，并促进了 NKC-1 菌株在 CIPC 污染环境中的生物修复潜力，随后释放氨、氯离子和二氧化碳。
