Khmelenina V N, Sakharovskiĭ V G, Reshetnikov A S, Trotsenko Iu A
Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Russia.
Mikrobiologiia. 2000 Jul-Aug;69(4):465-70.
The 1H-NMR analysis of methanol extracts of halophilic and halotolerant alkaliphilic methanotrophs isolated from the soda lakes of Southern Transbaikal and Tuva showed that bacterial cells grown at an optimum salinity accumulated mainly sucrose and 5-oxo-1-proline, whereas cells adapted to 0.5-1.0 M NaCl additionally synthesized ectoine. A more detailed study showed that nitrogen deficiency in the growth medium of Methylobacter alcaliphilus 20Z decreased the synthesis of nitrogen-containing osmoprotectants, ectoine and 5-oxo-1-proline. M. alcaliphilus 20Z cells exhibited activities of UDP-glucose pyrophosphorylase and sucrose-phosphate synthase involved in sucrose synthesis. Glutamine synthetase in vitro did not require NH4+ ions, which implies that this enzyme is involved in 5-oxo-1-proline synthesis. Cells grown at high salinity exhibited elevated levels of aspartate kinase, aspartate-semialdehyde dehydrogenase, and ectoine synthase. This suggests that ectoine is synthesized via aspartate and aspartate-semialdehyde, i.e., via the route earlier established for extremely halophilic bacteria.
对从南贝加尔湖和图瓦的苏打湖分离出的嗜盐和耐盐嗜碱甲烷氧化菌的甲醇提取物进行的¹H-NMR分析表明，在最佳盐度下生长的细菌细胞主要积累蔗糖和5-氧代-1-脯氨酸，而适应0.5-1.0 M NaCl的细胞还额外合成了四氢嘧啶。更详细的研究表明，嗜碱甲基杆菌20Z生长培养基中的氮缺乏会降低含氮渗透保护剂、四氢嘧啶和5-氧代-1-脯氨酸的合成。嗜碱甲基杆菌20Z细胞表现出参与蔗糖合成的UDP-葡萄糖焦磷酸化酶和蔗糖磷酸合酶的活性。体外谷氨酰胺合成酶不需要NH₄⁺离子，这意味着该酶参与5-氧代-1-脯氨酸的合成。在高盐度下生长的细胞中，天冬氨酸激酶、天冬氨酸半醛脱氢酶和四氢嘧啶合成酶的水平升高。这表明四氢嘧啶是通过天冬氨酸和天冬氨酸半醛合成的，即通过先前为极端嗜盐细菌确定的途径合成。
