Abundance of planktonic methane-oxidizing bacteria in a subtropical reservoir

Abstract

Methane-oxidizing bacteria (MOB) are regarded as key players in aquatic ecosystems, which can mitigate greenhouse gas emissions to the atmosphere. Among phylogenetically diverse MOB, those of the phylum Proteobacteria have been regarded as major methane oxidizers in environments, and they are classified into two major groups, type I and type II. Another group of MOB, Candidatus Methylomirabilis oxyfera and its close relatives have also been detected in various environments, but their predominance over proteobacterial MOB has hardly ever been reported. Feitsui Reservoir (FTR) is a subtropical reservoir situated in Taiwan, where the predominance of M. oxyfera -like phylotypes in a planktonic MOB community was first reported. In this study, planktonic MOB of three types ( M. oxyfera -like, type I and type II) were quantified with catalyzed reporter deposition-fluorescence in situ hybridization, to reveal seasonal variation and vertical distribution in the FTR. The MOB were enumerated for 161 samples obtained from 8 water depths on 23 sampling days over 16 months. The results obtained in this study will provide valuable basic data for a better understanding of MOB communities in the environment, giving insights into the global methane budget.

Integrating isotopic, microbial, and modeling approaches to understand methane dynamics in a frequently disturbed deep reservoir in Taiwan

“…The coupling effect has a time delay because of the time required for sedimentation of particulate organic matter from the pelagic zone to the benthic zone and for subsequent biogeochemical processes in benthic habitats (sediment plus deep water column), which supply resources to zooplankton through methane-based food webs (Ho et al 2016). Second, our microbial ecology studies (Kojima et al 2014;Kobayashi et al 2016) and other existing evidence (refs. in Fig.…”

“…Molecular analyses of bacterial communities indicated that the taxonomic composition of MOB (i.e., anaerobic MOB phylogenetically close to NC10 and aerobic Types I and II) changed seasonally and vertically (Kojima et al 2014;Kobayashi et al 2016). However, because of the limited availability of quantitative data, MOB functional activity in the food web model was parameterized following an earlier experimental study (Harrits and Hanson 1980).…”

Identification of aquatic consumer trophic pathways in four volcanic tropical lakes using fatty acid biomarkers

“…3). This was also in contrast to tropical and subtropical lakes, in which Type II is widely distributed throughout the oxic layer (Zigah et al, 2015;Kobayashi et al, 2016). Although MOBs are commonly present through the whole water column (Lew and Glinska-Lewczuk, 2018), they have low methane oxidation activity in surface waters due to the inhibitory effect of strong light (Dumestre et al, 1999;Murase et al, 2005).…”

“…MOB subsidize zooplankton production in oligotrophic to mesotrophic lakes (Bastviken et al, 2004;Kankaala et al, 2010;Ho et al, 2016) and sometimes provide the dominant carbon pathway for zooplankton during unproductive seasons (Taipale et al, 2007). The MOB are divided into three major taxa, Type I, Type II, and NC10, which are differently distributed both vertically and geographically (Kobayashi et al, 2016;Ghashghavi et al, 2019). Since they produce taxon-specific FAs based on different metabolic pathways for the assimilation of formaldehyde (Hanson and Hanson, 1996), these specific FAs can be used as tracers for aquatic consumers' methane-derived trophic pathways (Sanseverino et al, 2012).…”

Food web properties of the recently constructed, deep subtropical Fei-Tsui Reservoir in comparison with the ancient Lake Biwa

“…Long-term monitoring of methanotrophic food webs is of ecological importance in understanding how carbon cycling is altered in lakes affected by anthropogenic activities. In the FTR, it has been reported that MOBs dominate profundal bacterial communities, showing remarkable vertical and seasonal variations in community compositions (Kojima et al, 2014;Kobayashi et al, 2016). Itoh et al (2015) experimentally demonstrated that the methane oxidation activity is highest in deep sub-oxic layers, in which both dissolved methane and oxygen are available to MOBs.…”