Fessler Mathias, Madsen Jonas Stenløkke, Zhang Yifeng
Department of Environmental and Resource Engineering, Technical University of Denmark, Kongens Lyngby, Denmark.
Section of Microbiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark.
Front Microbiol. 2023 Mar 17;14:1150091. doi: 10.3389/fmicb.2023.1150091. eCollection 2023.
is part of a specialized group of microbes with the unique ability to exchange electrons with insoluble materials, such as iron oxides and electrodes. Therefore, plays an essential role in the biogeochemical iron cycle and microbial electrochemical systems. In this ability is primarily dependent on electrically conductive nanowires that link internal electron flow from metabolism to solid electron acceptors in the extracellular environment. Here we show that when carrying conjugative plasmids, which are self-transmissible plasmids that are ubiquitous in environmental bacteria, reduces insoluble iron oxides at much slower rates. This was the case for all three conjugative plasmids tested (pKJK5, RP4 and pB10). Growth with electron acceptors that do not require expression of nanowires was, on the other hand, unaffected. Furthermore, iron oxide reduction was also inhibited in , but not in where electron export is nanowire-independent. As determined by transcriptomics, presence of pKJK5 reduces transcription of several genes that have been shown to be implicated in extracellular electron transfer in , including and . These results suggest that conjugative plasmids can in fact be very disadvantageous for the bacterial host by imposing specific phenotypic changes, and that these plasmids may contribute to shaping the microbial composition in electrode-respiring biofilms in microbial electrochemical reactors.
是一类特殊微生物群体的一部分，具有与不溶性物质（如氧化铁和电极）交换电子的独特能力。因此，在生物地球化学铁循环和微生物电化学系统中发挥着重要作用。在 中，这种能力主要依赖于导电纳米线，这些纳米线将内部电子流从新陈代谢连接到细胞外环境中的固体电子受体。在这里我们表明，当携带接合质粒时（接合质粒是环境细菌中普遍存在的自我传递质粒）， 还原不溶性氧化铁的速度要慢得多。所有测试的三种接合质粒（pKJK5、RP4 和 pB10）都是这种情况。另一方面，使用不需要纳米线表达的电子受体进行生长不受影响。此外， 在 中氧化铁还原也受到抑制，但在电子输出不依赖纳米线的 中则不受抑制。通过转录组学确定，pKJK5 的存在会降低几个已被证明与 细胞外电子转移有关的基因的转录，包括 和 。这些结果表明，接合质粒实际上可能通过施加特定的表型变化对细菌宿主非常不利，并且这些质粒可能有助于塑造微生物电化学反应器中电极呼吸生物膜中的微生物组成。
