电缆细菌(Cable bacteria)对水体沉积物有机污染的响应与调控机制

Cable bacteria which were chemoorganotrophic filamentous Desulfobulbaceae have been discovered to commonly exist in sediment and efficiently control both the cathodic and anodic reactions and the associated long-distance electron transport. However, the function of cable bacteria for in-situ remediation of organic polluted aquatic sediments is presently known. We hypothesize that cable bacteria would play important roles in in-situ remediation of organic polluted aquatic sediments; the sediment microbial respiration and metabolic networks would be significantly regulated by the enhancements of conductivities of cable bacteria, consequently promoting the in-situ biodegradation of organic pollutants. In this project, a suite of remediation technologies and advanced microbial eco-physiological approaches will be combined to explore the function and enhancement mechanisms of cable bacteria to in in-situ remediation of organic polluted aquatic sediments. The responses of cable bacteria to organic pollution and the functions of cable bacteria on the biodegradation of organic pollutants in sediments will be determined by combining the field investigations and laboratory experiments. Furthermore, the relationships between the conductivities of cable bacteria and the efficiencies of in-situ remediation will be illuminated by microbial respiration regulations. The possible enhancement strategies and mechanisms for in-situ remediation of organic polluted aquatic sediments based on the conductivity of cable bacteria will also be proposed. The study aims to provide new insights into the in-situ remediation of organic polluted aquatic sediments and lead the new theories and technologies for in-situ sediment bioremediation based on the functions of cable bacteria.

电缆细菌(Cable bacteria)是最近被证实的、普遍存在于水体沉积物中、具有跨越氧化还原环境进行长距离电子传递功能、归属于Desulfobulbaceae科的有机化能营养型长线状细菌。推测：电缆细菌极有可能是有机污染水体沉积物原位修复的重要驱动者；强化电缆细菌的导电活性将有效调动系统中微生物的呼吸和代谢网络，加速有机污染物的原位降解转化。本项目将现场调查与实验室模拟研究紧密结合，在深入探讨电缆细菌对水体沉积物有机污染的响应方式及其对有机污染物原位降解转化的驱动作用基础上，结合微生物原位呼吸调控，提出基于电缆细菌导电活性的有机污染水体沉积物原位修复强化措施，揭示电缆细菌对水体沉积物有机污染的响应与调控机制。本研究将从一个全新的视角揭示有机污染水体沉积物原位修复机理，并有望开辟基于电缆细菌功能活性的水体沉积物原位修复理论和技术研究方向。

本项目以我国有机污染问题较为突出的珠江三角洲地区水体沉积物为主要研究对象，以典型有机污染水体沉积物中电缆细菌结构和功能活性特点原位调查为基础，深入探讨电缆细菌对水体沉积物中有机污染的响应方式及对有机污染物原位降解转化的驱动作用。研究结果表明：受污染水体沉积物中存在多种电缆细菌。这些电缆细菌具有糖酵解途径、糖异生途径、丙酮酸代谢和TCA循环的大部分基因，以及WL碳固定通路和乙酸代谢相关基因。电缆细菌的富集生物可显著提高沉积物中多环芳烃的生物可利用性。上覆水溶氧浓度升高能够显著提高沉积物中电缆细菌的丰度和产电硫氧化活性，造成厌氧沉积物pH值显著下降并伴随硫酸根离子累积，进而影响沉积物中微生物群落组成结构和种间互作模式变化。伴随电缆细菌增殖，大量功能菌群（硫代谢、有机质降解、电活性微生物等）丰度明显上升并与电缆细菌形成紧密的互利共生网络，影响沉积物碳、硫循环等关键生态过程。尤其是以硫酸盐为代谢底物的硫还原菌群（Sulfate-reducing-bacteria，SRB）丰度显著上升，其硫酸盐呼吸耦合复杂有机质降解活性有效促进了沉积物中多环芳烃（PAH）等复杂污染物的原位降解速率。基于上述结果，率先提出了电缆细菌介导的上覆水溶氧波动影响沉积物生物地化学循环的电动氧气扩散机制（Electric Oxygen Extension，EOE）。相关工作为基于电缆细菌导电活性的有机污染水体沉积物原位强化修复技术的建立提供了科学理论指导。