BIOSYNTHESIS OF VITAMIN B12 AND ANAEROBIC METABOLISM

维生素B12是人体必需的营养素，它只能合成 被微生物感染。 关于它的生物合成或其生理特性， 重要性的微生物。沙门氏菌 鼠伤寒沙门氏菌能够完全合成B12，但只有 在厌氧条件下。 因为复杂的遗传学可以在 这种细菌，我们提出了一种遗传学方法来了解 维生素B12的生物合成。 我们会找出 参与（可能超过30），并将追求这条途径是如何 特别强调如何涉及O2。 对肠道细菌的遗传和生化研究已经做了大量的工作 在有氧条件下。 关于这件事的细节我们知之甚少 这些生物的厌氧生活方式，尽管几乎所有的 与人类宿主的相互作用（定植和发病机制）在 缺乏氧气 我们怀疑B12的厌氧产生 表明存在大量代谢活动， 仅在厌氧条件下发生，完全未知。 我们建议接近 通过研究B12在厌氧代谢中的作用， 沙门氏菌的生活

Vitamin B12 is an essential nutrient for humans, that is only synthesized by microbes. Little is known about its biosynthesis or its physiological importance to the microbes that produce it. The bacterium Salmonella typhimurium is capable of a complete synthesis of B12, but does so only under anaerobic conditions. Since sophisticated genetics can be done in this bacterium, we propose a genetic approach to understanding the biosynthesis of vitamin B12 in this organism. We will identify the genes involved (probably an excess of thirty) and will pursue how this pathway is regulated with special emphasis on how 02 is involved. The genetic and biochemical study of enteric bacteria has been done largely under aerobic conditions. Relatively little is known about the details of the anaerobic life-style of these organisms even though virtually all their interactions with human hosts (colonization and pathogenesis) proceed in the absence of oxygen. We suspect that production of B12 anaerobically indicates the existence of a substantial body of metabolic activity that occurs only anaerobically and is totally unknown. We propose to approach these aspects of metabolism by studying the role of B12 in the anaerobic life of Salmonella.