Gemmatimonas phototrophica is, so far, the only described phototrophic species of the bacterial phylum Gemmatimonadetes. Its cells contain a unique type of photosynthetic complex with the reaction center surrounded by a double ring antenna, however they can also grow in the dark using organic carbon substrates. Its photosynthesis genes were received via horizontal gene transfer from Proteobacteria. This raises two questions; how the horizontally transferred photosynthesis apparatus has integrated into the cellular machinery, and how much light-derived energy actually contributes to the cellular metabolism? To address these points, the photosynthetic reactions were studied on several levels, from photophysics of the reaction center to cellular growth. Flash photolysis measurements and bacteriochlorophyll fluorescence kinetic measurements documented the presence of fully functional type-2 reaction centers with a large light harvesting antenna. When illuminated, the bacterial cells reduced their respiration rate by 58 ± 5%, revealing that oxidative phosphorylation was replaced by photophosphorylation. Moreover, illumination also more than doubled the assimilation rates of glucose, a sugar that is mostly used for respiration. Finally, light increased the growth rates of Gemmatimonas phototrophica colonies on agar plates. All the presented data provide evidence that photosynthetic complexes are fully integrated into cellular metabolism of Gemmatimonas phototrophica, and are able to provide a substantial amount of energy for its metabolism and growth.

Gemmatimonas phototrophica是，到目前为止，唯一描述的细菌门芽单胞菌门的光养物种。它的细胞包含独特类型的光合复合物，其反应中心被双环天线围绕，但是它们也可以在黑暗中使用有机碳底物生长。其光合作用基因通过变形杆菌的水平基因转移。这提出了两个问题。水平转移的光合作用设备如何整合到细胞机械中，以及多少光衍生能量实际上对细胞的代谢有贡献？为了解决这些问题，从反应中心的光物理学到细胞生长，从几个层面研究了光合作用反应。闪光光解测量和细菌叶绿素荧光动力学测量结果表明，存在功能齐全的2型反应中心，并带有大型光收集天线。照亮后，细菌细胞的呼吸速率降低了58±5％，表明氧化磷酸化被光磷酸化所取代。此外，光照还使葡萄糖的同化率提高了一倍以上，一种主要用于呼吸的糖。最后，光线增加了琼脂平板上的Gemmatimonas phototrophica菌落。所有提供的数据提供了光合复合物完全整合到光合芽孢杆菌的细胞代谢中的证据，并能够为其代谢和生长提供大量能量。