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.

• Klíčová slova
• biological soil crust, cold climate, cyanobacteria, deglaciations, desert ecosystems, high-altitude ecosystem, methanogens, stable carbon isotope,
• Publikační typ
• časopisecké články MeSH

Denaturant gradient gel electrophoresis (DGGE) enables insight into the diversity of the studied microbial communities on the basis of separation of PCR amplification products according to their nucleotide sequence composition. However, the success of the method is accompanied by the inherent appearance of various sequence artifacts that bias the impression of community structure by generating additional bands representing no virtual microbes. PCR-DGGE artifacts require optimization of the method when aiming at the phylogenetic identification of the selected DGGE bands. The aim of our study was to develop a procedure which will increase the reliability of the identification. Samples of rumen fluid were used for the optimization since they contain a complex microbial community that supports the generation of artifactual bands. An optimized procedure following band excision and elution of microbial DNA is proposed including nuclease treatment, selection of DNA polymerase with proofreading activity, and cloning prior to sequencing and identification analysis.

• MeSH
• bachor mikrobiologie   MeSH
• Bacteria klasifikace   genetika   izolace a purifikace   MeSH
• denaturační gradientová gelová elektroforéza metody   MeSH
• DNA bakterií genetika   MeSH
• fylogeneze MeSH
• techniky typizace bakterií metody   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• hodnotící studie MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DNA bakterií MeSH