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Rhizosphere bacterial carbon turnover is higher in nucleic acids than membrane lipids: implications for understanding soil carbon cycling

Malik, Ashish A.; Dannert, Helena; Griffiths, Robert I.; Thomson, Bruce C.; Gleixner, Gerd. 2015 Rhizosphere bacterial carbon turnover is higher in nucleic acids than membrane lipids: implications for understanding soil carbon cycling. Frontiers in Microbiology, 6, 268. 9, pp. 10.3389/fmicb.2015.00268

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Abstract/Summary

Using a pulse chase 13CO2 plant labeling experiment we compared the flow of plant carbon into macromolecular fractions of rhizosphere soil microorganisms. Time dependent 13C dilution patterns in microbial cellular fractions were used to calculate their turnover time. The turnover times of microbial biomolecules were found to vary: microbial RNA (19 h) and DNA (30 h) turned over fastest followed by chloroform fumigation extraction-derived soluble cell lysis products (14 days), while phospholipid fatty acids (PLFAs) had the slowest turnover (42 days). PLFA/NLFA 13C analyses suggest that both mutualistic arbuscular mycorrhizal and saprophytic fungi are dominant in initial plant carbon uptake. In contrast, high initial 13C enrichment in RNA hints at bacterial importance in initial C uptake due to the dominance of bacterial derived RNA in total extracts of soil RNA. To explain this discrepancy, we observed low renewal rate of bacterial lipids, which may therefore bias lipid fatty acid based interpretations of the role of bacteria in soil microbial food webs. Based on our findings, we question current assumptions regarding plant-microbe carbon flux and suggest that the rhizosphere bacterial contribution to plant assimilate uptake could be higher. This highlights the need for more detailed quantitative investigations with nucleic acid biomarkers to further validate these findings.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.3389/fmicb.2015.00268
CEH Sections: Acreman
ISSN: 1664-302X
Additional Information. Not used in RCUK Gateway to Research.: Open Access paper - full text available via Official URL link
Additional Keywords: 13C tracer experiment, bacteria, carbon, DNA, fungi, PLFA, RNA, soil
NORA Subject Terms: Agriculture and Soil Science
Date made live: 08 Jul 2015 15:32 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/511228

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