Wang Linlin, Zhao Mingliang, Du Xiongfeng, Feng Kai, Gu Songsong, Zhou Yuqi, Yang Xingsheng, Zhang Zhaojing, Wang Yingcheng, Zhang Zheng, Zhang Qi, Xie Baohua, Han Guangxuan, Deng Ye
Institute of Marine Science and Technology, Shandong University, Qingdao, China.
CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.
Front Microbiol. 2023 Jan 6;13:1076610. doi: 10.3389/fmicb.2022.1076610. eCollection 2022.
Wetlands are natural sources of methane (CH) emissions, providing the largest contribution to the atmospheric CH pool. Changes in the ecohydrological environment of coastal salt marshes, especially the surface inundation level, cause instability in the CH emission levels of coastal ecosystems. Although soil methane-associated microorganisms play key roles in both CH generation and metabolism, how other microorganisms regulate methane emission and their responses to inundation has not been investigated. Here, we studied the responses of prokaryotic, fungal and cercozoan communities following 5 years of inundation treatments in a wetland experimental site, and molecular ecological networks analysis (MENs) was constructed to characterize the interdomain relationship. The result showed that the degree of inundation significantly altered the CH emissions, and the abundance of the gene for methanotrophs shifted more significantly than the gene for methanogens, and they both showed significant positive correlations to methane flux. Additionally, we found inundation significantly altered the diversity of the prokaryotic and fungal communities, as well as the composition of key species in interactions within prokaryotic, fungal, and cercozoan communities. Mantel tests indicated that the structure of the three communities showed significant correlations to methane emissions ( < 0.05), suggesting that all three microbial communities directly or indirectly contributed to the methane emissions of this ecosystem. Correspondingly, the interdomain networks among microbial communities revealed that methane-associated prokaryotic and cercozoan OTUs were all keystone taxa. Methane-associated OTUs were more likely to interact in pairs and correlated negatively with the fungal and cercozoan communities. In addition, the modules significantly positively correlated with methane flux were affected by environmental stress (i.e., pH) and soil nutrients (i.e., total nitrogen, total phosphorus and organic matter), suggesting that these factors tend to positively regulate methane flux by regulating microbial relationships under inundation. Our findings demonstrated that the inundation altered microbial communities in coastal wetlands, and the fungal and cercozoan communities played vital roles in regulating methane emission through microbial interactions with the methane-associated community.
湿地是甲烷（CH）排放的天然来源，对大气中的CH库贡献最大。沿海盐沼生态水文环境的变化，尤其是地表淹没水平，导致沿海生态系统CH排放水平不稳定。尽管与土壤甲烷相关的微生物在CH的产生和代谢中都起着关键作用，但其他微生物如何调节甲烷排放及其对淹没的反应尚未得到研究。在这里，我们研究了在湿地实验场地进行5年淹没处理后原核生物、真菌和丝足虫群落的反应，并构建了分子生态网络分析（MENs）来表征域间关系。结果表明，淹没程度显著改变了CH排放，甲烷氧化菌基因的丰度变化比产甲烷菌基因更显著，且它们与甲烷通量均呈显著正相关。此外，我们发现淹没显著改变了原核生物和真菌群落的多样性，以及原核生物、真菌和丝足虫群落内相互作用的关键物种组成。Mantel检验表明，这三个群落的结构与甲烷排放显著相关（P < 0.05），表明所有这三个微生物群落直接或间接地促成了该生态系统的甲烷排放。相应地，微生物群落之间的域间网络显示，与甲烷相关的原核生物和丝足虫OTU都是关键分类群。与甲烷相关的OTU更有可能成对相互作用，并且与真菌和丝足虫群落呈负相关。此外，与甲烷通量显著正相关的模块受到环境胁迫（即pH值）和土壤养分（即总氮、总磷和有机质）的影响，这表明这些因素倾向于通过在淹没条件下调节微生物关系来正向调节甲烷通量。我们的研究结果表明，淹没改变了沿海湿地的微生物群落，真菌和丝足虫群落通过与甲烷相关群落的微生物相互作用在调节甲烷排放中发挥了重要作用。
