Giménez-Gallego G, del Valle-Tascón S, Ramírez J M
Arch Microbiol. 1976 Aug;109(1-2):119-25. doi: 10.1007/BF00425123.
Anaerobic suspensions of Rhodospirillum rubrum cells which had been grown in the dark under low oxygen tension showed only a small increase of their ATP content when illuminated for 30 s. The same suspensions failed to start immediate growth in the light. Both high light-induced ATP levels and immediate phototrophic growth were elicited by small amounts of oxygen which were insufficient by themselves to raise the ATP levels or to support growth in the dark. The oxygen requirement for growth disappeared after some time of anaerobic illumination and was not observed in suspensions of cells which had been grown in the light under anaerobiosis. Furthermore, these phototrophic cells reached the maximum levels of ATP when illuminated in the absence of oxygen. Strain F11, a mutant derivative of Rhodospirillum rubrum which lacked the ability to photoreduce oxygen in vitro, needed abnormally high amounts of oxygen to increase its ATP levels and to grow in the light. Besides, KCN inhibited the increase of ATP levels in illuminated mutant cells but not in wild type cells. An additional difference between both strains was that the oxygen requirement for growth did not disappear in the mutant after some time of anaerobic incubation in the light. To explain these observations, it is proposed that the photosynthetic system of semiaerobically-grown Rhodospirillum rubrum becomes overreduced under anaerobiosis. The oxygen-photoreducing system, which is impaired in the mutant is apparently used to oxidize the photosynthetic system to its optimal redox state, carrying electrons to oxygen or to other endogenous acceptors which are formed during incubation in the light. The mutant seems to replace the defective system by a cyanide-sensitive pathway which may reduce oxygen but not the alternative endogenous acceptors.
在低氧张力下于黑暗中培养的深红红螺菌细胞的厌氧悬浮液，光照30秒后其ATP含量仅略有增加。相同的悬浮液在光照下未能立即开始生长。少量氧气可引发高光诱导的ATP水平升高和立即的光养生长，而这些氧气本身不足以提高ATP水平或支持黑暗中的生长。经过一段时间的厌氧光照后，生长所需的氧气需求消失，在厌氧条件下于光照中培养的细胞悬浮液中未观察到这种需求。此外，这些光养细胞在无氧光照时达到ATP的最高水平。菌株F11是深红红螺菌的突变衍生物，缺乏体外光还原氧气的能力，在光照下增加其ATP水平和生长需要异常大量的氧气。此外，KCN抑制光照下突变细胞中ATP水平的增加，但不抑制野生型细胞中的增加。这两种菌株的另一个差异是，在光照下进行一段时间的厌氧培养后，突变体中生长所需的氧气需求并未消失。为了解释这些观察结果，有人提出，在半好氧条件下生长的深红红螺菌的光合系统在厌氧条件下会过度还原。突变体中受损的氧光还原系统显然用于将光合系统氧化到其最佳氧化还原状态，将电子传递给氧气或传递给在光照培养过程中形成的其他内源性受体。突变体似乎通过一条对氰化物敏感的途径来替代有缺陷的系统，该途径可能还原氧气，但不能还原替代内源性受体。
