铁呼吸细菌Shewanella统筹呼吸作用的新机制及其环境意义的研究

独特的呼吸作用是铁呼吸细菌(IRB)推动元素循环、作为生物修复和能源微生物的关键。IRB同时维持有氧和厌氧呼吸的电子传递链，耗费能量和营养，却为何未被选择压力淘汰，目前尚不清楚。课题组前期报道了模式IRB Shewanella中受氧气调控的转录因子FlrA。RNA-Seq显示有氧条件下，FlrA激活厌氧呼吸而抑制有氧呼吸，是控制上述现象的新型呼吸调控因子。基于此，本项目拟围绕FlrA的调控与被调控机制及生物学作用展开：①结合ChIP-Seq和RNA-Seq，区分FlrA直接和间接调控的基因；分析直接调控的分子机制；突变体库筛选介导间接调控的中间基因。②分析不同电子受体对FlrA表达的影响；筛选介导该影响的基因。③通过竞争实验，分析FlrA对Shewanella适应和利用三种常见电子受体的作用。通过解析FlrA响应电子受体以统筹呼吸和环境适应的机制，深化对IRB呼吸作用生物和环境意义的认识。

Based on their unique respiration, iron reducing bacteria (IRB) not only play a role in the biogeochemical cycling of many elements, but also are used for bioremediation and energy production. IRB maintain an electron transfer web for anaerobic and aerobic respiration under aerobic condition. It is still unknown how such an energy- and nutrient-consuming regulation has retained under selection pressure. We have previously reported an oxygen-regulated transcription factor FlrA in model IRB Shewanella. RNA-Seq analysis showed that FlrA inhibits aerobic respiration while activates anaerobic respiration under the aerobic condition. These results suggested that FlrA is the key factor to control the aerobic and anaerobic respiration. In this study, we will illustrate how FlrA orchestrates expression of genes involved in respiration in response to available electron acceptors. First, we will distinguish genes that are directly and indirectly regulated by FlrA, and reveal the underlying transcription regulation. Second, we will test the influence of common electron acceptors in FlrA expression as well as the underlying mechanism. Third, we will evaluate the effect of FlrA on the fitness of Shewanella in response to electron acceptors. In summary, this study will deepen our understanding of the biological and environmental significance of IRB respiration and underlying regulation.