Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, 159 Long Pan Road, Nanjing, 210037, China.
College of Tea and Food Science and Technology, Jiangsu Polytechnic College of Agriculture and Forestry, Jurong, 212400, China.
BMC Biotechnol. 2018 May 9;18(1):26. doi: 10.1186/s12896-018-0438-x.
Dihydro-β-ionone is a principal aroma compound and has received considerable attention by flavor and fragrance industry. The traditional method of preparing dihydro-β-ionone has many drawbacks, which has restricted its industrial application. Therefore, it is necessary to find a biotechnological method to produce dihydro-β-ionone.
In this study, the enoate reductase with high conversion efficiency of β-ionone to dihydro-β-ionone, DBR1, was obtained by screening four genetically engineered bacteria. The product, dihydro-β-ionone, was analyzed by GC and GC-MS. The highest dihydro-β-ionone production with 308.3 mg/L was detected in the recombinant strain expressing DBR1 which was later on expressed and purified. Its optimal temperature and pH were 45 °C and 6.5, respectively. The greatest activity of the purified enzyme was 356.39 U/mg using β-ionone as substrate. In the enzymatic conversion system, 1 mM of β-ionone was transformed into 91.08 mg/L of dihydro-β-ionone with 93.80% of molar conversion.
DBR1 had high selectivity to hydrogenated the 10,11-unsaturated double bond of β-ionone as well as high catalytic efficiency for the conversion of β-ionone to dihydro-β-ionone. It is the first report on the bioconversion of β-ionone to dihydro-β-ionone by using enoate reductase.
二氢-β-紫罗兰酮是一种主要的香气化合物，受到了香料和香精行业的广泛关注。传统的二氢-β-紫罗兰酮制备方法存在许多缺点，限制了其工业应用。因此，有必要寻找一种生物技术方法来生产二氢-β-紫罗兰酮。
在本研究中，通过筛选四种基因工程菌，获得了对β-紫罗兰酮到二氢-β-紫罗兰酮具有高转化率的烯醇还原酶 DBR1。通过 GC 和 GC-MS 对产物二氢-β-紫罗兰酮进行分析。在表达 DBR1 的重组菌中检测到最高的二氢-β-紫罗兰酮产量为 308.3mg/L，随后进行了表达和纯化。其最适温度和 pH 值分别为 45°C 和 6.5。以β-紫罗兰酮为底物时，纯化酶的最大酶活为 356.39U/mg。在酶转化体系中，1mM 的β-紫罗兰酮转化为 91.08mg/L 的二氢-β-紫罗兰酮，摩尔转化率为 93.80%。
DBR1 对β-紫罗兰酮的 10,11-不饱和双键具有高选择性，对β-紫罗兰酮转化为二氢-β-紫罗兰酮具有高催化效率。这是首次报道利用烯醇还原酶将β-紫罗兰酮生物转化为二氢-β-紫罗兰酮。
