Graduate School of Environmental and Life Science, Okayama University, Okayama, Japan.
Biosci Biotechnol Biochem. 2021 Mar 24;85(4):989-997. doi: 10.1093/bbb/zbaa121.
Norathyriol is an aglycone of a xanthonoid C-glycoside mangiferin that possesses different bioactive properties useful for humans compared to mangiferin. Mangiferin is more readily available in nature than norathyriol; thus, efficient mangiferin conversion into norathyriol is desirable. There are a few reports regarding mangiferin C-deglycosylation because of the C-C bond resistance toward acid, alkaline, and enzyme hydrolysis. In this study, we isolated a mangiferin-deglycosylating bacterium strain KM7-1 from the mouse intestine. 16S rDNA sequencing indicated that KM7-1 belongs to the Bacillus genus. Compared to the taxonomically similar bacteria, the growth characteristic of facultative anaerobic and thermophilic resembled, yet only Bacillus sp. KM7-1 was able to convert mangiferin into norathyriol. Resting cells of Bacillus sp. KM7-1 obtained from aerobic cultivation at 50 °C showed high norathyriol formation from 1 m m of mangiferin. Norathyriol formation can be conducted either under aerobic or anaerobic conditions, and the reaction depended on time and bacterial amount.
诺拉曲醇是一种荭酮类 C-糖苷芒果苷的苷元，与芒果苷相比，它具有对人类不同的生物活性。芒果苷在自然界中比诺拉曲醇更容易获得；因此，将芒果苷有效地转化为诺拉曲醇是可取的。由于 C-C 键对酸、碱和酶水解的抵抗力，有关芒果苷 C-去糖基化的报道很少。在这项研究中，我们从老鼠肠道中分离出一株芒果苷去糖基化细菌 KM7-1。16S rDNA 测序表明，KM7-1 属于芽孢杆菌属。与分类上相似的细菌相比，兼性厌氧和嗜热的生长特性相似，但只有芽孢杆菌 KM7-1 能够将芒果苷转化为诺拉曲醇。从 50°C 好氧培养获得的芽孢杆菌 KM7-1 的静止细胞显示出从 1m m 的芒果苷中形成高量的诺拉曲醇。诺拉曲醇的形成可以在有氧或无氧条件下进行，反应取决于时间和细菌数量。
