地杆菌生物膜驱动土壤氧化铁还原的电信号-化学信号协同通讯机制

地杆菌是驱动土壤铁循环的最重要微生物，其还原氧化铁矿物的关键是在铁矿表面聚集形成细菌数庞大的生物膜。微生物个体间的通讯交流（cell-cell communication）是微生物聚集成膜的前提。本项目基于地杆菌作为革兰氏阴性电活性菌的特点，提出地杆菌还原土壤铁矿的“电信号—化学信号协同通讯”假说，以Geobacter metallireducens GS-15为研究对象，以申请人前期构建的两株突变株——敲除高丝氨酸内酯（AHL）受体蛋白基因的G.m∆luxR和敲除钾离子通道阀门控制蛋白基因的G.m∆trkA——为切入点，系统研究“K+通道介导的电信号”及“AHL介导的化学信号”在地杆菌通讯中的角色与功能，揭示电信号“远程（毫米尺度）招募细菌成员”与化学信号“近程（微米尺度）调控生物膜形成”的协同机制，有助于从分子水平认知电活性生物膜的形成过程，为理解土壤矿物与微生物互作提供新的科学视角。

Geobacter species plays a central role in the iron redox cycling. The key of Geobacter to reduce iron-oxide mineral is to form biofilm with a huge number of bacteria on the surface of the mineral. The cell-cell communication is the premise of microbial aggregation. Based on characteristics of Gram-negative electroactive bacteria which involving Geobacter, this project proposes the “Collaborative electrical-chemical signaling communication” hypothesis of Geobacter biofilm during the iron-oxide reduction process in soils. Geobacter metallireducens GS-15 and two mutants engineered by our group, G.m∆luxR deficient in the acylhomoserinre lactone (AHL) receptor and G.m∆trkA deficient in the gated domain of potassium channels, are taken as the research objects to systematically study roles and functions of the “K+-channel-mediated electrical signal” and the “AHL-mediated chemical signal” in Geobacter communication, and to reveal the collaborative communication mechanism of “electrical signaling in charge of recruiting long-range (millimeter scale) members” and “chemical signaling responsible for short-range (micrometer scale) regulation”. Results from this project are expected to further understand the formation of electroactive biofilm at the molecular level, and provide a new scientific perspective for interactions between soil minerals and microbes.