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The calculation of parameters involved in the kinetics of the microbial soil reactions linked to the carbon cycle is strongly limited by the methodologies employed. Hence, a mathematical model is proposed to quantify easily the specific rate of catabolic activity A(c) by microcalorimetry based on Belaich's model. It permits to quantify A(c) from the plots of the heat flow rate vs. time recorded from soil samples amended with glucose. It was applied for several soil samples collected in the Amazon. The results obtained were compared, and statistical and graphical analyses were used to provide the biophysical significance of A(c) in soils. Results suggest that A(c) could be used as an empirical measure of stress. It correlates positively with the heat yield, Y(Q/X), of the soil microbial growth reactions, indicating that higher specific rates of catabolic activity cause higher dissipation of energy per unit of cell, yielding less-efficient metabolic reactions, which could affect negatively the soil quality. It is strongly affected by the initial microbial population and by the percentage of nitrogen in the samples. The statistical analysis also demonstrated that A(c) is more sensitive to changing environmental conditions than Y(Q/X), yielding more-accurate information about the soil metabolic processes.

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“…If the heat flow rate (dQ/dt) emitted by every bacterium is w [28], then F 0 N 0 ¥ w and F t N t ¥ w. Thus, we have:…”

Section: Experimental Partmentioning

confidence: 99%

Calculation of the Specific Rate of Catabolic Activity (A_c) from the Heat Flow Rate of Soil Microbial Reactions Measured by Calorimetry: Significance and Applications

Barros

Gallego

Feijóo

2004

Chemistry & Biodiversity

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Performance of calorimetric methods for the investigation of microbial systems in combination with additional sensors

et al. 2005

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Calorimetric methods are used in combination with online oxygen measurement (using an amperometric sensor) and determination of the optical density (using a fibre optic sensor) to investigate microbial growth behaviour. The calorimetric curves of different batch experiments show a characteristic and reproducible course. Changes in the slope of the DeltaT-time curves indicate the effects of limiting factors on the microbial activity during the cultivation. A first limitation could be correlated with the depletion of oxygen in the medium; a second correlates with the depletion of the carbon source. Measurements of optical density in some cases provide reliable information about the growth of a microorganism culture. Our measurements show a good correlation of the universal calorimetric signal (heat-time curve) to the signal of the miniaturised photometric (OD) sensor.

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Calorimetric approach to metabolic carbon conversion efficiency in soils

Barros

Salgado

Rodríguez-Añón

et al. 2010

J Therm Anal Calorim

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Cited by 15 publications

References 8 publications

Calculation of the Specific Rate of Catabolic Activity (A_c) from the Heat Flow Rate of Soil Microbial Reactions Measured by Calorimetry: Significance and Applications

Calculation of the Specific Rate of Catabolic Activity (A_c) from the Heat Flow Rate of Soil Microbial Reactions Measured by Calorimetry: Significance and Applications

Performance of calorimetric methods for the investigation of microbial systems in combination with additional sensors

Calorimetric approach to metabolic carbon conversion efficiency in soils

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Untitled

Cited by 15 publications

References 8 publications

Calculation of the Specific Rate of Catabolic Activity (Ac) from the Heat Flow Rate of Soil Microbial Reactions Measured by Calorimetry: Significance and Applications

Calculation of the Specific Rate of Catabolic Activity (Ac) from the Heat Flow Rate of Soil Microbial Reactions Measured by Calorimetry: Significance and Applications

Performance of calorimetric methods for the investigation of microbial systems in combination with additional sensors

Calorimetric approach to metabolic carbon conversion efficiency in soils

Contact Info

Product

Resources

About

Calculation of the Specific Rate of Catabolic Activity (A_c) from the Heat Flow Rate of Soil Microbial Reactions Measured by Calorimetry: Significance and Applications

Calculation of the Specific Rate of Catabolic Activity (A_c) from the Heat Flow Rate of Soil Microbial Reactions Measured by Calorimetry: Significance and Applications