Both catabolic and anabolic heterotrophic microbial activity proceed in frozen soils
2010 (English)In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 107, no 49, 21046-21051 p.Article in journal (Refereed) Published
A large proportion of the global soil carbon pool is stored in soils of high-latitude ecosystems in which microbial processes and production of greenhouse gases proceed during the winter months. It has been suggested that microorganisms have limited ability to sequester substrates at temperatures around and below 0 °C and that a metabolic shift to dominance of catabolic processes occurs around these temperatures. However, there are contrary indications that anabolic processes can proceed, because microbial growth has been observed at far lower temperatures. Therefore, we investigated the utilization of the microbial substrate under unfrozen and frozen conditions in a boreal forest soil across a temperature range from -9 °C to +9 °C, by using gas chromatography-isotopic ratio mass spectrometry and (13)C magic-angle spinning NMR spectroscopy to determine microbial turnover and incorporation of (13)C-labeled glucose. Our results conclusively demonstrate that the soil microorganisms maintain both catabolic (CO(2) production) and anabolic (biomass synthesis) processes under frozen conditions and that no significant differences in carbon allocation from [(13)C]glucose into [(13)C]CO(2) and cell organic (13)C-compounds occurred between +9 °C and -4 °C. The only significant metabolic changes detected were increased fluidity of the cell membranes synthesized at frozen conditions and increased production of glycerol in the frozen samples. The finding that the processes in frozen soil are similar to those in unfrozen soil has important implications for our general understanding and conceptualization of soil carbon dynamics in high-latitude ecosystems.
Place, publisher, year, edition, pages
2010. Vol. 107, no 49, 21046-21051 p.
soil organic matter mineralization, 13CO2, 13C-NMR
IdentifiersURN: urn:nbn:se:umu:diva-38218DOI: 10.1073/pnas.1008885107ISI: 000285050800038PubMedID: 21078966OAI: oai:DiVA.org:umu-38218DiVA: diva2:373263