沉积物电缆细菌的生长特征及其对物质循环影响的研究进展

沉积物-水界面物质循环主要受铁锰化合物和微生物氧化还原过程的影响. 微生物氧化还原通常发生在细胞周质空间和外膜表层，或通过微生物纳米导线、细胞被膜等机制发生在细胞间. 近年来，电缆细菌介导的长距离电子传递机制的发现，使得微生物氧化还原反应的发生距离从纳米级扩展到厘米级. 本文重点综述了电缆细菌的生理特性及其对沉积物-水界面物质循环的影响，总结了电缆细菌的环境效应及未来的研究方向. 电缆细菌主要栖息于高硫化物含量、高电导率和低生物扰动的咸水沉积物中，在淡水沉积物中较少见. 电缆细菌对硫化物的氧化是一种反向硫酸盐还原过程，使得表层沉积物处于偏碱性的环境中，并利用多种电子受体来实现硫氧化，从而在与其他微生物的竞争中获得优势. 电缆细菌通常以O₂为电子受体将H₂S和FeS氧化为硫酸盐，并在沉积物-水界面处形成一层铁氧化物保护层，在吸附间隙水中磷的同时也阻止了其他物质的释放. 电缆细菌能够通过溶解FeS间接地促进硝酸盐异化还原作用，进而影响沉积物氮循环. 未来有必要加强微尺度电缆细菌对物质循环的影响和电缆细菌与其他细菌的协作关系研究，建议创新电缆细菌的纯化培育条件并开展其在硫污染沉积物修复中的应用，从而为水生态环境保护工作的开展提供技术支持. 

Research Progress on Growth Characteristics of Cable Bacteria and Their Effects on Material Cycling in Sediments

The material cycling at the sediment-water interface is primarily affected by the redox processes of iron and manganese oxides and microorganisms. Microbial redox processes usually occur in the periplasm space and the outer membrane of cells or are mediated by nanowire and conductive biofilms between cells. Recently, the long-distance electron transport mediated by cable bacteria has been discovered in different environments, which extended the known length of electron transport from nanometer scale to centimeter scale. In this paper, we provide an overview of current understanding on the physiological characteristics of cable bacteria and their influences on material cycling at the sediment-water interface, then summarize the potential environmental significance of cable bacterial activities, and finally propose the future research perspectives in this field. Cable bacteria are frequently found in marine sediments with high sulfide content, high conductivity and less bioturbation. However, it is rarely observed in freshwater sediments. Sulfide oxidization mediated by cable bacteria is an inverse process of sulfate reduction, resulting in alkalization of the surface sediments. In addition, cable bacteria can use various electron acceptors for sulfide oxidation, which gives them a strong competitive advantage over other microorganisms. Generally, cable bacteria oxidize H₂S and FeS into sulfate using O₂ as electron acceptor. This process generates a firewall of iron oxides in surface sediments, which can efficiently sequestrate phosphorus in porewater and prevent other material release. Besides, the metabolism of cable bacteria can affect nitrogen cycling by indirectly promoting dissimilatory nitrate reduction to ammonium (DNRA) through iron sulfide dissolution. In future, it is necessary to study the effects of cable bacteria on sediment material cycling and their cooperative relationship with other microbe communities at micro-scale. Moreover, it is necessary to develop the pure culture technology of cable bacteria and its application in the remediation of sulphur-contaminated sediments to provide technical support for future water ecological environment protection.