Vertical profiles of sediment methanogenic potential and communities in two plateau freshwater lakes

Abstract

Abstract. Microbial methanogenesis in sediment plays a crucial role in CH4 emission from freshwater lake ecosystems. However, knowledge of the layer-depth-related changes of methanogen community structure and activities in freshwater lake sediment is still limited. The present study was conducted to characterize the methanogenesis potential in different sediment-layer depths and the vertical distribution of microbial communities in two freshwater lakes of different trophic status on the Yunnan Plateau (China). Incubation experiments and inhibitor studies were carried out to determine the methanogenesis potential and pathways. 16S rRNA and mcrA genes were used to investigate the abundance and structure of methanogen and archaeal communities, respectively. Hydrogenotrophic methanogenesis was mainly responsible for methane production in sediments of both freshwater lakes. The layer-depth-related changes of methanogenesis potential and the abundance and community structure of methanogens were observed in both Dianchi Lake and Erhai Lake. Archaeal 16S rRNA and mcrA genes displayed a similar abundance change pattern in both lakes, and the relative abundance of methanogens decreased with increasing sediment-layer depth. Archaeal communities differed considerably in Dianchi Lake and Erhai Lake, but methanogen communities showed a slight difference between these two lakes. However, methanogen communities illustrated a remarkable layer-depth-related change. Order Methanomicrobiales was the dominant methanogen group in all sediments, while Methanobacteriales showed a high proportion only in upper layer sediments. The trophic status of the lake might have a notable influence on the depth-related change pattern of methanogenesis activity, while the methanogen community structure was mainly influenced by sediment depth.

Diversity of methanogenic archaea in freshwater sediments of lacustrine ecosystems

“…A plenty of research has been done in the field of methanogenesis in different types of lake ecosystems such as humic, oligotrophic, and meromictic lakes but shallow eutrophic and mesotrophic lakes have not been given much attention [26,[34][35][36][37][38]. The substrates play a significant role during selection of methanogenic pathway, such that the substrate present in the eutrophic and mesotrophic lakes may prefer a different pathway of methanogenesis from that of other lakes in consideration [26]. In order to determine the diversity of sedimentary methanogens of lakes, it is required to combine the culture-independent and -dependent techniques together.…”

“…Sequencing of both 16S rRNA and mcrA genes were performed for analyzing the structure and abundance of methanogenic communities of the sediments of two freshwater lakes of Yunnan Plateau, China [26]. The sedimentary methanogens displayed a pre-dominantly hydrogenotrophic pathway for the methanogenesis process in both the lakes studied.…”

“…In fresh water environments, active archaeal community is engaged in nitrogen conversion and CH 4 release, predominantly in benthonic water and sediments [24]. In FIGURE 1 Distribution of methanogens depending on the pathway of metabolism [11] lacustrine ecosystems, CH 4 emitted at a rate of about 6-16% naturally [25,26]. A huge quantity of CH 4 is emitted by the process of microbial methanogenesis in the sediments of freshwater lakes [27,28].…”

Trophic Status Is Associated With Community Structure and Metabolic Potential of Planktonic Microbiota in Plateau Lakes

“…Eutrophication is one of the biggest of such challenges; it changes the diversity and composition of lake organisms and poses a serious threat to ecosystem service function (Liu et al, 2012; Shi et al, 2016; Dong et al, 2018). To date, most studies have concentrated on microbial communities in sediment from Yun-Gui Plateau lakes with different trophic levels (Bai et al, 2012; Dai et al, 2016; Yang et al, 2017a, b). Only a few studies have focused on microbiota in lake surface waters, in which the microorganisms are more sensitive to lake eutrophication than those in sediment (Zeng et al, 2019).…”

Metal contaminations impact archaeal community composition, abundance and function in remote alpine lakes

“…Hence, our results underlined again the critical ecological consequences of long range metal contaminations, which have reduced the abundance and activity of methanogens in impacted sediments. A huge amount of methane is produced by the process of microbial methanogenesis in lacustrine sediments Yang et al, 2017). During this process, methanogens play a key role in the mineralization of organic matter by removing the excess hydrogen and fermentation products generated by other forms of anaerobic respiration.…”