我国主要河口沉积物中多环芳烃细菌降解及生物修复强化方式的研究进展

Degradation of polycyclic aromatic hydrocarbons in sediments of main estuaries in China by bacteria and the methods to enhance the degradation

摘要:

河口是海洋及陆地交互作用的集中地带，其生态环境的健康状况对所在地区人类居住及社会经济的可持续发展十分重要。近年来，河口城市的快速发展导致了大量的多环芳烃(polycyclicaromatic hydrocarbons，PAHs)在河口沉积物中积累，持久地影响水生生态系统的健康，其降解与转化逐渐成为近年来的研究热点。本文总结发现，我国主要河口(珠江口、长江口、辽河口、海河口)沉积物中的PAHs降解菌主要分布于假单胞菌门、放线菌门及芽孢杆菌门，其中克雷伯氏菌属、芽孢杆菌属及假单胞菌属报道较多。在河口沉积物中，PAHs的细菌降解主要是通过低效率的厌氧降解途径。低氧、高盐度是PAHs细菌降解的不利条件，温度与pH值的变化也为实地生物修复的应用效率带来了不确定性。表面活性剂、营养物与外源电子受体的添加以及共代谢作用均可促进沉积物细菌对PAHs的降解。目前多数研究以实验室规模开展，而河口沉积物生境复杂，建议未来针对河口沉积物的环境特点进行PAHs降解功能菌株种质资源的挖掘，并根据实际情况灵活制定强化策略。本综述为进一步从我国主要河口沉积物中筛选PAHs高效降解菌及其利用提供了思路与参考。

Abstract:

Estuaries are the transition zones between land and sea, and the health of the ecosystem is essential to the surrounding residents and the sustainable economic development. In recent years, amid the rapid development of the cities nearby, a large number of the permanent polycyclic aromatic hydrocarbons (PAHs) have accumulated in the sediments of estuaries, posing a threat to the health of the aquatic ecosystems. As a result, the degradation and transformation of PAHs have attracted the interest of scholars. According to previous studies, Pseudomonadota, Actinobacteria, and Bacillota dominate the PAHs-degrading bacteria in sediments of main estuaries (Pearl River Estuary, Yangtze River Estuary, Liaohe River Esturay, and Haihe River Estuary) in China, among which Klebsiella, Bacillus, and Pseudomonas have been frequently reported. Bacteria degrade PAHs in estuarine sediments mainly through the anaerobic pathway which is characterized by low efficiency. Low oxygen and high salinity in estuarine sediments are unfavorable for the bacterial degradation of PAHs, and the changeable temperature and pH result in uncertain efficiency of bioremediation. The addition of surfactants, nutrients, and exogenous electron receptors and the co-metabolism can promote the bacterial degradation of PAHs in sediments. At the moment, most studies have been carried out in laboratory, but the environmental conditions of estuarine sediments are complex. Therefore, it is suggested to screen PAHs-degrading strains according to the environmental characteristics of estuarine sediments in the future, and flexibly formulate strategies to enhance the degradation according to the actual situation. This review is expected to serve as a reference for further screening and utilization of indigenous PAHs-degrading bacteria in the sediments of major estuaries in China.