SGER: Isolation of a Photoferrotrophic Bacterium from Iron Enriched Environments

光合铁营养细菌（进行光合作用的细菌 并使用亚铁作为还原剂）。 这 有机体是一种假设的光养生物， 的 放氧光系统II反应中心的演化 在 蓝藻和远亲醌型反应 紫色细菌和绿挠曲菌的中心。 大 差异 在反应中心多肽的序列中， 差距 还原电位和还原剂的性质 使用 这些远亲生物的光合作用 的 可能存在一个或多个生物体， 进化 光合作用的中间产物。 这样一种中间有机体 光化学氧化的铁可以解释 在出现之前的太古代出现氧化铁 的 产氧光合作用 虽然中间生物可能 有 存在于反应中心的进化历史中， 今天可能已经灭绝了。 因此，本研究具有探索性 和高风险。 合适的环境已经确定， 仔细分析了微生境的存在， 持续光铁营养。 这些环境包括富含铁的 酸性矿山排水区，铁泉，和沉积物 富含铁的浅湖 这些微生境将由 使用 微电极来寻找暴露于 光 含亚铁高，硫化物低， 一旦找到合适的微生境， 样品 将收集用于显微镜检查、色素含量和培养， 试图分离出光养铁生物

A photoferrotrophic bacterium (one that does photosynthesis and uses ferrous iron as a reductant) will be sought. This organism is a hypothetical phototroph that is a missing link in the evolution of the oxygen-evolving photosystem II reaction center in cyanobacteria and the distantly related quinone type reaction centers of the purple bacteria and Chloroflexus. Large differences in the sequences of the reaction center polypeptides and large gaps in the reduction potentials and hence the nature of reductants used for photosynthesis in these distantly related organisms suggest the probable existence of one or more organisms that were evolutionary intermediates in photosynthesis. Such an intermediate organism that photochemically oxidized iron would explain the geochemical appearance of oxidized iron in the Archean eon before the advent of oxygenic photosynthesis. Although intermediate organisms may have existed in the evolutionary history of the reaction center, they may be extinct today. Consequently this research is exploratory and high risk in nature. Suitable environments have been identified and will be carefully analyzed for the presence of microhabitats the could sustain photoferrrotrophy. These environments include iron-rich acid mine drainage areas, iron springs, and the sediments of shallow iron rich lakes. The microhabitats will be sought by using microelectrodes to find anoxic microzones that are exposed to light and that are high in ferrous iron, low in sulfide, and of neutral or acidic pH. Once suitable microhabitats have been found, samples will be collected for microscopy, pigment content, and culture to attempt to isolate a photoferrotroph.