Department of Biochemistry, Tzu Chi University, Hualien 97004, Taiwan; Institute of Medical Sciences, Tzu Chi University, Hualien 97004, Taiwan; Department of Biochemistry, University of Medicine 1 Yangon, Myanmar.
Institute of Medical Sciences, Tzu Chi University, Hualien 97004, Taiwan; Department of Laboratory Medicine and Biotechnology, Tzu Chi University, Hualien 97004, Taiwan.
Enzyme Microb Technol. 2020 Sep;139:109586. doi: 10.1016/j.enzmictec.2020.109586. Epub 2020 May 21.
(-)-Borneol is a bicyclic plant secondary metabolite. Optically pure (-)-borneol can only be obtained from plants, and demand exceeds supply in China. In contrast, chemically synthesized borneol contains four different stereoisomers. A strain of Pseudomonas monteilii TCU-CK1, isolated in Hualien, Taiwan, can accumulate (-)-borneol in growth culture and selectively degrades the other three isomers when chemically synthesized borneol is used as sole carbon source. This (-)-borneol production method can be scaled-up for production of large quantities in the future. More importantly, laborious plant cultivation and harvest is no longer required. The main enzyme that appears in this degradation pathway, borneol dehydrogenase (BDH), and the genome sequence of TCU-CK1 are reported. The k/K values of TCU-CK1 BDH on (+)- and (-)-borneol are 538.4 ± 38.4 and 17.7 ± 1.1 (s mM), respectively. About ∼30 fold difference in the k/K value between (+)-borneol and (-)-borneol was observed, in good agreement with the fact that TCU-CK1 prefers to degrade (+)-borneol, rather than (-)-borneol. A BDH isozyme was identified in a strain in which the primary BDH gene had been knocked out. (-)-Camphor can work as an inhibitor of BDH with a K of 1.03 ± 0.11 mM at pH 7.0, leading to the accumulation of (-)-borneol in culture. (Patent pending).
(-)-龙脑是一种双环植物次生代谢物。光学纯的(-)-龙脑只能从植物中获得，而中国的需求超过了供应。相比之下，化学合成的龙脑含有四个不同的立体异构体。一株从中国台湾花莲分离得到的假单胞菌（Pseudomonas monteilii）TCU-CK1 在生长培养中可以积累（-）-龙脑，并且当使用化学合成的龙脑作为唯一碳源时，它可以选择性地降解其他三种异构体。这种（-）-龙脑生产方法可以在未来进行大规模生产。更重要的是，不再需要费力的植物种植和收获。报告了该降解途径中出现的主要酶，龙脑脱氢酶（BDH），以及 TCU-CK1 的基因组序列。TCU-CK1 BDH 对（+）-和（-）-龙脑的 k/K 值分别为 538.4 ± 38.4 和 17.7 ± 1.1（s mM）。（+）-龙脑和（-）-龙脑之间的 k/K 值差异约为 30 倍，这与 TCU-CK1 更倾向于降解（+）-龙脑而不是（-）-龙脑的事实相符。在主要 BDH 基因被敲除的菌株中鉴定出了一种 BDH 同工酶。（-）-樟脑可以作为 BDH 的抑制剂，在 pH 7.0 时 K 值为 1.03 ± 0.11 mM，导致培养物中（-）-龙脑的积累。（专利待批）。
