Microbial minorities modulate methane consumption through niche partitioning

Abstract

Microbes catalyze all major geochemical cycles on earth. However, the role of microbial traits and community composition in biogeochemical cycles is still poorly understood mainly due to the inability to assess the community members that are actually performing biogeochemical conversions in complex environmental samples. Here we applied a polyphasic approach to assess the role of microbial community composition in modulating methane emission from a riparian floodplain. We show that the dynamics and intensity of methane consumption in riparian wetlands coincide with relative abundance and activity of specific subgroups of methane-oxidizing bacteria (MOB), which can be considered as a minor component of the microbial community in this ecosystem. Microarray-based community composition analyses demonstrated linear relationships of MOB diversity parameters and in vitro methane consumption. Incubations using intact cores in combination with stable isotope labeling of lipids and proteins corroborated the correlative evidence from in vitro incubations demonstrating c-proteobacterial MOB subgroups to be responsible for methane oxidation. The results obtained within the riparian flooding gradient collectively demonstrate that niche partitioning of MOB within a community comprised of a very limited amount of active species modulates methane consumption and emission from this wetland. The implications of the results obtained for biodiversity-ecosystem functioning are discussed with special reference to the role of spatial and temporal heterogeneity and functional redundancy.

Methane oxidation coupled to oxygenic photosynthesis in anoxic waters

“…Our nanoSIMS results are thus consistent with our molecular studies, which also failed to detect alpha-proteobacterial pmoA in situ (Figure 3c). These results are also consistent with previous studies of other freshwater lakes (for example, Blees et al, 2014), rice-field soils and wetlands Qiu et al, 2008;Bodelier et al, 2013) where predominantly gamma-MOB were found to be active.…”

Large‐scale biogeography and environmental regulation of methanotrophic bacteria across boreal inland waters

“…Rare taxa, however, might actually represent a very responsive part of the community and may have exert a disproportionate influence on biogeochemical cycles (Pedrós‐Alió, ). For example, the experimental rewetting of soil communities resulted in a net reduction of methane emissions driven by the resuscitation of rare methanotrophic bacteria (Aanderud, Jones, Fierer, & Lennon, ), and efficient methane consumption from a wetland was driven by methanotrophs that constituted <0.1% of the communities (Bodelier et al, ). Consequently, the low relative abundance of methanotrophs may not imply lack of activity or a minor biogeochemical role.…”

Termites Facilitate Methane Oxidation and Shape the Methanotrophic Community

“…Previously, the upland grassland soil clusters were detected in other upland soils (15,51) and thought to form the dominant population responsible for atmospheric methane oxidation in a desert soil (52). However, they were rarely detected in methane-emitting environments and are not as strictly correlated with environments which act as a sink for atmospheric methane as the USC groups (5,16,27,(53)(54)(55). Although putative atmospheric methane oxidizers (USC␥) (13) cluster within the Methylococcaceae, cultured Methylobacter and Methylococcus species have not been shown to oxidize methane at low or atmospheric concentrations; their role as atmospheric methane oxidizers remains elusive.…”