微生物介导的热融湖碳循环关键过程研究进展

Advances in Microbe Mediated Key Processes of the Carbon Cycle in Thermokarst Lakes

极地超常的变暖引起多年冻土不断退化并形成热融湖,该过程释放温室气体与气候变暖形成正反馈。微生物在碳循环不同环节均发挥着重要作用,理解热融湖中微生物对碳循环的调控机制,对于应对未来气候变化具有重要意义。综述了热融湖微生物参与的关键碳循环过程:梳理了热融湖形成过程和形成后微生物群落组成与分布;对有机碳分解、产甲烷和甲烷氧化等过程中涉及的主要微生物类群进行了总结;凝练了微生物对碳循环的调控机制及受环境变化的影响机制与要素。基于已有研究,得出如下认识:(1)多年冻土融化形成热融湖主要以陆生有机质为主,一些营养物质如磷酸盐、植物纤维素和亮氨酸残基等生物聚合物从陆地进入水体。(2)在多年冻土融化形成热融湖过程中,随着温度和通气条件的改善,有机质及各种生物聚合物可利用性增加了微生物功能基因多样性,提高了微生物对有机碳的分解潜势。温度、底物、溶解氧等和微生物群落的变化引起微生物代谢途径等的改变,从而影响了甲烷产生、甲烷氧化及固碳等过程,最终影响碳循环。(3)为了加深对热融湖中微生物介导碳循环过程的理解,提出了未来研究的方向:借助宏基因组技术及室内培养实验更加清晰地揭示微生物对碳循环各个过程的调节机制,加强不同环境条件下热融湖碳排放的野外观测,探索利用微生物来减轻气候变化的负面影响。

As a result of global warming,the melting of ice-rich permafrost causes the ground to collapse,thereby creating thermokarst lakes,while the greenhouse effect caused by the concurrent release of greenhouse gases results in a positive feedback with climate warming.Microorganisms play important roles in various aspects of the carbon cycle.Understanding the mechanisms of microbial regulation of the carbon cycle in thermally melting lakes is of great significance for coping with future climate change.Therefore,by combining previous studies,this paper first elucidates the formation process of thermokarst lakes and the microorganisms inhabiting these special habitats;subsequently,the main microorganisms involved in organic carbon decomposition,methane production,and methane oxidation,and the regulation mechanisms and influencing factors are analyzed in detail.Based on this analysis,we conclude the following:①The organic matter in thermokarst lakes originates from the land,while some nutrients,such as phosphates,plant biopolymers,and leucine residues,are also transported from the land to the water.②With improvements in temperature and aeration conditions,the availability of most nutrients increases the genetic diversity of microorganisms and promotes their roles in organic carbon decomposition.Changes in temperature,substrate,dissolved oxygen,and microbial community affect the processes of methane production,methane oxidation,and carbon sequestration,thereby affecting the carbon cycle.③Some deficiencies in previous studies are summarized,and a new research perspective is proposed to deepen our understanding of microbial involvement in the carbon cycle in thermokarst lakes.With the help of metagenomic technology and incubation,the regulatory mechanisms of microbes for the carbon cycle can be revealed more clearly,and field observations of carbon emissions from thermokarst lakes under different environmental conditions can be strengthened.Exploring the use of microbes for mitigating the negative effects of climate change should be based on the above fundamental research.