Gong Xiaowei, Ma Guanghui, Duan Yanqing, Zhu Donglai, Chen Yongkuan, Zhang Ke-Qin, Yang Jinkui
State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming, 650091, People's Republic of China.
R & D Center of China Tobacco Yunnan Industrial Co., Ltd., Kunming, 650024, People's Republic of China.
World J Microbiol Biotechnol. 2016 Nov;32(11):188. doi: 10.1007/s11274-016-2147-8. Epub 2016 Sep 27.
Nicotine in tobacco is harmful to health and the environment, so there is an environmental requirement to remove nicotine from tobacco and tobacco wastes. In this study, the biotransformation of nicotine by Rhodococcus sp. Y22 was investigated, and three metabolites (NIC1, NIC4 and NIC5) were isolated by column separation, preparative TLC and solid plate's method, respectively. NIC1 was identified as 6-hydoxynicotine based on the results of NMR, MS, HPLC-UV and HRESIMS analysis; NIC4 was a novel compound and identified as 5-(3-methyl-[1,3]oxazinan-2-ylidene)-5H-pyridin-2-one based on the results of NMR, MS and UV analysis; NIC5 was identified as nicotine blue based on the results of NMR and MS analysis. Meanwhile, two metabolites NIC2 and NIC3 were identified as 6-hydroxy-N-methylmyosmine and 6-hydroxypseudooxynicotine by HRESIMS analysis, respectively. According to these metabolites, the possible pathway of nicotine degradation by Rhodococcus sp. Y22 was proposed. The nicotine can be transformed to nicotine blue through two pathways (A and B), and 6-hydroxy-N-methylmyosmine is the key compound, which can be converted to 6-hydroxypseudooxynicotine (pathway A) and 5-(3-methyl-[1,3]oxazinan-2-ylidene)-5H-pyridin-2-one (pathway B), respectively. Moreover, the encoding gene of nicotine dehydrogenase, ndh, was amplified from Rhodococcus sp. Y22, and its transcriptional level could be up-regulated obviously under nicotine induction. Our studies reported the key metabolites and possible biotransformation pathway of nicotine in Rhodococcus sp. Y22, and provided new insights into the microbial metabolism of nicotine.
烟草中的尼古丁对健康和环境有害，因此存在从烟草及烟草废弃物中去除尼古丁的环境要求。在本研究中，对红球菌属菌株Y22对尼古丁的生物转化进行了研究，并分别通过柱色谱分离、制备薄层层析和固体平板法分离出了三种代谢产物（NIC1、NIC4和NIC5）。基于核磁共振（NMR）、质谱（MS）、高效液相色谱-紫外检测（HPLC-UV）和高分辨电喷雾电离质谱（HRESIMS）分析结果，NIC1被鉴定为6-羟基尼古丁；NIC4是一种新化合物，基于NMR、MS和紫外分析结果被鉴定为5-(3-甲基-[1,3]恶唑烷-2-亚基)-5H-吡啶-2-酮；基于NMR和MS分析结果，NIC5被鉴定为尼古丁蓝。同时，通过HRESIMS分析，两种代谢产物NIC2和NIC3分别被鉴定为6-羟基-N-甲基麦斯明和6-羟基假氧化尼古丁。根据这些代谢产物，提出了红球菌属菌株Y22降解尼古丁的可能途径。尼古丁可通过两条途径（A和B）转化为尼古丁蓝，6-羟基-N-甲基麦斯明是关键化合物，它可分别转化为6-羟基假氧化尼古丁（途径A）和5-(3-甲基-[1,3]恶唑烷-2-亚基)-5H-吡啶-2-酮（途径B）。此外，从红球菌属菌株Y22中扩增出了尼古丁脱氢酶的编码基因ndh，其转录水平在尼古丁诱导下可明显上调。我们的研究报道了红球菌属菌株Y22中尼古丁的关键代谢产物和可能的生物转化途径，为尼古丁的微生物代谢提供了新的见解。
