Methane-cycling microorganisms in soils of a high-alpine altitudinal gradient

Abstract

Methanogens and methanotrophs play unique roles as producers and consumers of the greenhouse gas methane (CH4) in soils, respectively. Here, we aimed to reveal whether and to which extent methane-cyclers occur in high-alpine soils, and to assess their spatial distribution along an altitudinal gradient (2700-3500 m) in the Austrian Alps at sites located within the alpine (2700-2900 m), the alpine-nival (3000-3100 m) and the nival belts (3200-3500 m). Methanococcales and Methanocella spp. were most abundant among all quantified methanogenic guilds, whereas Methanosarcinales were not detected in the studied soil. The detected methanogens seem to be capable of persisting despite a highly oxic low-temperature environment. Methanogenic and methanotrophic activities and abundances of methanotrophs, Methanococcales and Methanocella spp. declined with altitude. Methanogenic and methanotrophic abundances were best explained by mean annual soil temperature and dissolved organic carbon, respectively. Alpine belt soils harbored significantly more methane-cyclers than those of the nival belt, indicating some influence of plant cover. Our results show that methanogens are capable of persisting in high-alpine cold soils and might help to understand future changes of these environments caused by climate warming.

Proteogenomic analyses indicate bacterial methylotrophy and archaeal heterotrophy are prevalent below the grass root zone

“…These studies found that methanol-oxidizing enzymes of Proteobacteria have micro- and nanomolar affinity for methanol, the highest activity occurring in the root-associated soil, and that methylotrophic communities thrive under the full range of plant diversity and soil pH (Radajewski et al, 2002; Stacheter et al, 2013). Further, methylotrophic methanogenesis can occur under aerobic conditions (Hofmann et al, 2016; Karl et al, 2008; Metcalf et al, 2012). However, in our study, no methyl-coenzyme M reductase complex ( mcrA ) gene was predicted in any dataset.…”

“…Prior studies of microbial functions (i.e., ammonia oxidation, methylotrophy) in soil have used targeted approaches such as gene amplification (qPCR, pyrosequencing) (Hofmann et al, 2016; Pester et al, 2012; Stacheter et al, 2013), culturing of isolates and enrichments (Beck et al, 2014). More recently, metagenomic methods have been applied to soil samples with the objective of providing a cultivation- and primer-independent view of microbial community composition and functional capacities (Delmont et al, 2015; Hultman et al, 2015; Luo et al, 2014; White et al, 2016).…”

Side by side? Vascular plant, invertebrate, and microorganism distribution patterns along an alpine to nival elevation gradient

“…Archaeal distribution is more pronouncedly affected by elevation than bacteria, leading to an increasing bacteria/archaea ratio with increasing elevation (Hofmann et al 2016b). The ratio between methaneproducing archaea and methane-oxidizing bacteria (mainly belonging to the phylum of proteobacteria) was surprisingly constant throughout the entire elevation gradient at Mt.…”

“…Only the abundance of Methanocella is shown separately in the results because it may stand for the copy number of all methanogenic archaea, and was the only group that was found in all soil samples of a study investigating more than thirty sites across Tyrol (Hofmann et al 2016c). For more details concerning the microbial parameters measured along the elevation gradient of our site, see Hofmann et al (2016b).…”

“…For alpine soil arthropod abundance, experimental warming was most effective when combined with nutrient addition (Hågvar and Klanderud 2009), whereas a long-term warming experiment had no effect on richness and abundance of springtails in alpine subarctic ecosystems (Alatalo, Jägerbrand, and Čuchta 2015). Changes in occurrence and activities of microorganisms would be especially relevant to climate change considering their attributes as key players for methane formation and consumption, belonging to methanogenic archaea and methanotrophic bacteria, respectively (Crutzen and Lelieveld 2001;Hofmann et al 2016b;Praeg, Wagner, and Illmer 2017).…”