Ryzhkova E P, Briukhanov A L
Mikrobiologiia. 2009 Jan-Feb;78(1):5-11.
Methanosarcina barkeri is capable of synthesizing large amounts of corrinoids, compounds of the vitamin B12 group, although not cobalamin. In the present work, exogenous cobalamin was demonstrated to upregulate DNA synthesis in M. harkeri cell suspensions incubated under air. The effect is similar to the one in Propionibacterium freudenreichii cells, though less pronounced. The growth of the archaeon under anaerobic conditions was shown to be suppressed by cobalamin and 5,6-dimethylbenzimidazole. The data obtained suggest the presence of a corrinoid-dependent ribonucleotide reductase in the archaeon cells which provides for deoxyribose precursors for DNA biosynthesis independently of the presence of molecular oxygen in the medium. Growth suppression under anoxic conditions by cobalamin and 5,6-dimethylbenzimidazole may be due to a decrease in the concentration of factor III, a polyfunctional corrinoid dominating in M. barkeri cells.
巴氏甲烷八叠球菌能够合成大量类咕啉，即维生素B12族化合物，但不能合成钴胺素。在本研究中，已证明外源性钴胺素可上调在空气中孵育的巴氏甲烷八叠球菌细胞悬液中的DNA合成。该效应与费氏丙酸杆菌细胞中的效应相似，不过不太明显。已表明钴胺素和5,6-二甲基苯并咪唑会抑制古生菌在厌氧条件下的生长。所获得的数据表明古生菌细胞中存在一种类咕啉依赖性核糖核苷酸还原酶，该酶可独立于培养基中分子氧的存在为DNA生物合成提供脱氧核糖前体。钴胺素和5,6-二甲基苯并咪唑在缺氧条件下对生长的抑制作用可能是由于因子III浓度降低所致，因子III是巴氏甲烷八叠球菌细胞中占主导地位的多功能类咕啉。
