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Oxygen consumption by soil microorganisms as affected by oxygen and carbon dioxide levels

Abstract : Models of soil anaerobiosis generally describe microbial O-2 consumption as independent of O-2 and CO2 concentrations. In the present work, the effects of these gases on soil respiration were studied using artificial and natural aggregates without gas transport limitation. The chemical reactions of CO2 in soil solution were analysed to assess the actual CO2 levels affecting microorganisms. Both O-2 and CO2 affected O-2 consumption, For artificial aggregates, respiration was partially inhibited by CO2 at all tested concentrations (4-12% (v/v) CO2). Respiration of natural aggregates was stimulated at 4% CO2 and inhibited at higher concentrations. These different aggregate behaviours could be attributed to changes in microbial populations associated with the preparation of artificial aggregates. A model based on Michaelis-Menten kinetics and including competitive inhibition by CO2, adequately described the effects of O-2 and CO2 concentrations on O-2 consumption by artificial aggregates. The model was partially modified to account for CO2 stimulation effect in natural aggregates. K-M values for O-2 consumption were 1.69% O-2 for artificial aggregates and 5.80% O-2 for natural aggregates. Calculations to estimate soil anaerobiosis showed that the effects of O-2 and CO2 on respiration may not be ignored to predict the anaerobic regions within aggregates. However, the dissolved CO2 corresponds to a small fraction of the mineral carbon present in soil solution, and its effect on microorganisms will depend on the position within the soil aggregate or the soil profile.
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Submitted on : Monday, June 1, 2020 - 7:03:50 PM
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Jorge Sierra, Pierre Renault. Oxygen consumption by soil microorganisms as affected by oxygen and carbon dioxide levels. Applied Soil Ecology, Elsevier, 1995, 2 (3), pp.175-184. ⟨10.1016/0929-1393(95)00051-L⟩. ⟨hal-02713577⟩



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