title: Methanogens at the top of the world: occurrence and potential activity of methanogens in newly deglaciated soils in high-altitude cold deserts in the Western Himalayas.
abstract: Methanogens typically occur in reduced anoxic environments. However, in recent studies it has been shown that many aerated upland soils, including desert soils also host active methanogens. Here we show that soil samples from high-altitude cold deserts in the western Himalayas (Ladakh, India) produce CH4 after incubation as slurry under anoxic conditions at rates comparable to those of hot desert soils. Samples of matured soil from three different vegetation belts (arid, steppe, and subnival) were compared with younger soils originating from frontal and lateral moraines of receding glaciers. While methanogenic rates were higher in the samples from matured soils, CH4 was also produced in the samples from the recently deglaciated moraines. In both young and matured soils, those covered by a biological soil crust (biocrust) were more active than their bare counterparts. Isotopic analysis showed that in both cases CH4 was initially produced from H2/CO2 but later mostly from acetate. Analysis of the archaeal community in the in situ soil samples revealed a clear dominance of sequences related to Thaumarchaeota, while the methanogenic community comprised only a minor fraction of the archaeal community. Similar to other aerated soils, the methanogenic community was comprised almost solely of the genera Methanosarcina and Methanocella, and possibly also Methanobacterium in some cases. Nevertheless, ~10(3) gdw(-1) soil methanogens were already present in the young moraine soil together with cyanobacteria. Our results demonstrate that Methanosarcina and Methanocella not only tolerate atmospheric oxygen but are also able to survive in these harsh cold environments. Their occurrence in newly deglaciated soils shows that they are early colonizers of desert soils, similar to cyanobacteria, and may play a role in the development of desert biocrusts.
authors.affiliation: Max Planck Institute for Terrestrial Microbiology Marburg, Germany.
authors.forename: Katrin
authors.initials: K
authors.lastname: Aschenbach
authors.affiliation: Max Planck Institute for Terrestrial Microbiology Marburg, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Conrad
authors.affiliation: Institute of Botany, Academy of Sciences of the Czech Republic Třeboň, Czech Republic.
authors.forename: Klára
authors.initials: K
authors.lastname: Reháková
authors.affiliation: Institute of Botany, Academy of Sciences of the Czech Republic Třeboň, Czech Republic.
authors.forename: Jiří
authors.initials: J
authors.lastname: Doležal
authors.affiliation: Institute of Botany, Academy of Sciences of the Czech Republic Třeboň, Czech Republic ; Faculty of Science, University of South Bohemia České Budějovice, Czech Republic.
authors.forename: Kateřina
authors.initials: K
authors.lastname: Janatková
authors.affiliation: Max Planck Institute for Terrestrial Microbiology Marburg, Germany.
authors.forename: Roey
authors.initials: R
authors.lastname: Angel
keywords: biological soil crust; cold climate; cyanobacteria; deglaciations; desert ecosystems; high-altitude ecosystem; methanogens; stable carbon isotope