Studies on the Plasmid of Photosynthetic Bacterium Rhodospirillum rubrum

光合细菌Rhodocellum rubum是一种紫色非硫细菌。在无氧光照条件下，它们能进行光合作用，而在有氧条件下，它们不能进行光合作用，只能进行异养生长。此外，在厌氧黑暗的条件下，它们可以在发酵提供ATP的情况下生长。这表明，红色红球藻能适应各种环境，对研究生物界的代谢进化具有重要意义。在殖民地中显示紫色的红色细胞用吖啶黄（一种吖啶染料）处理，在肉汤琼脂培养基上出现各种类型的着色;白色、粉红色、弱橙子和果肉。证明了白色（菌落）变体，表明它们没有质粒，尽管野生型菌株携带质粒，并且甚至在任何条件下都不能光合作用，因为它们没有细菌叶绿素和类胡萝卜素作为光合色素，也没有必须含有光合机构的色素体，用各种限制性内切酶消化分离的质粒，制作限制性内切酶图谱，并估计大小。数据显示质粒大小约为50个pais。用分离的质粒dna转化白色突变体，转化子恢复了光合色素合成和叶绿体形成的能力。当然，转移物能够进行光合作用。

Photosynthetic bacterium Rhodospirillum rubum is a kind of purple non-sulfur bacteria. In the conditions of anaerobic lighting, they can photosynthesize, whreas in the aerobic conditions they can not do photo synthesis but can grow only heterotrophically. Further,in the conditions of anaerobic darkness, they can grow with a supply of ATP from fermentation. That is, the R, rubrum can survive adaptively under various environments and thus it is useful for studies on the metabolic evolution in the biological world.It bas found in the course of the present strdies that when the R. rubrum cells, which show purple color in the colony, was treated with acriflavine, a kind of acridine dyes, various types of pigmentations appear on a broth agar medium; White, pink,weak orange, and flesh. The white(colony) variants was demonstrated to show that they have no a plasmid although the wild type strain carry the plasmid and could not photosyhtesize even under any conditions because they have no bacterio chlorophyll and carotenoid as photosynthetic pigments and no chromatophores, which have to contain photosynthetic machineries, in the cell.Plasmid isolated was digested by various types of restriction enzymes to make the restriciton enzyme map and to estimate the size. The data showed that the plasmid size is about 50 kilobase pais. When the white mutants were transformed by plasmid dna isolated, the transformants restored abilities of syntheses of the photosynthetic pigments and of formation of chloromato phore. It is of course that the transfermants are able to photosynthesize.