The Roles of Soil Microbes in the Global Environment

Abstract

Attention has been paid to CO₂ balance of atmosphere along with global warming. The soil stores carbon in organic matters twice as much as carbon in atmosphere, and, on the other hand, the soil releases CO₂ into atmosphere by soil respiration. Therefore, the soil has two characteristics as C storing warehouse and a supplier of CO₂. Though soil respiration is chiefly due to the activity of soil microbes, the behavior of them has been hardly evaluated from the aspect of the CO₂ generation. The microbe calorimeter is a suitable device for catching the behavior of the microbes in the soil nondestructively. In the present manuscript, the calorimetric studies about influences of soil microbes on the environmental condition were explained. A change in the metabolic heat (thermogram) of the soil microbes with decomposition of organic matters was similar to a change in the CO₂ generation under the same condition, and profiles of the thermograms and of the CO₂ generation curves varied according to the different kinds of organic matter and the soil. A microbe composition was known to change dynamically with decomposing the organic matters using the microbe calorimetry and the DGGE (Denaturing Gradient Gel Electrophoresis) technique. Soil microbes could not decompose a specific amino acid easily, and on the other hand, could decompose rapidly catechins and bio-degradable plastics beyond our expectation. The calorimetric method can offer the kinetically evaluating technique about the influence of herbicides, pesticides and heavy metals on the decomposing activity of soil microbes. The microbe calorimetry is useful for the investigation about the generation mechanism of CO₂ in the soil.