Study Of The Microbial Metabolic Activities By The Microcalorimetric Method

The biothemochemistry is an art of observation, identification, description, experimental investigation, and theoretical explanation of biological phenomena in the view of energy. Calorimetry is the most important tools in the fields of biothermochemistry. Microcalorimetry as a new kind of techniques has been widely used in life sciences, environmental sciences,clinical medicine and agrology for its advantages of high sensitivity, automability. The main interest in this research work was focused on metabolic characteristics of microbes. By using TAM-2277 Thermal Activity Monitor, we have studied the effects of the AlCl₃, CaCl₂ and the associated action of AlCl₃ and CaCl₂ on E.coli(DH5α) metabolic activity by the stopped-flow method, and studied the soil microbial metabolic activity by the ampoule method. The main research includes:1. The effects of AlCl₃, CaCl₂ and the associated action of AlCl₃ and CaCl₂ on the metabolic activity of E. coli(DH5α) were studied by the stopped-flow method. The experimental results show that the inhibitory effect of AlCl₃ on the growth metabolism of E.coli(DH5α), and the mechanism depends on the species of Al(III) in the solution; CaCl₂ has a stimulatory effect on the growth of E.coli(DH5α) at the low concentration, while inhibit at the high concentration; when the two compounds affect E.coli(DH5α) simultaneously, the mechanism is complicated, namely, there are antagonistic or cooperative interaction between AlCl₃ and CaCl₂. This depend on the relative concentrations of AlCl₃ and CaCl₂. It has not been reported that the microcalorimetry method study the effects of the two compounds on the metabolic activity of E.coli.2. The effects of different preserved temperatures on the microorganism activity of the Pingliang soil were studied by the ampoule method. Experimental results show that the heat production rate and the growth rate of the log phase of the soil microoganisms have a positive correlation with the preserved temperature from -20℃to 25℃. But there are the highest total heat production at 4℃, which shows that the soil microbial have the highest activity at this preserved temperature. The effects of preserved temperatures on the microorganism activity of the soil have not been reported previousely by microcalorimetry method.3. The differences of the microbial activity between the permafrost soil samples of different vegetation coverage and degradation in different degree in Tibetan Plateau were studied by the ampoule method. Experimental studies show that the structures of the permofrost microbial and thermal spectra shape of the frozen soils are similar under the same vegetation coverage and the total number of microorganisms is positive correlation with the total heat production, but the frozen soil microbial metabolic activity is small campared to ordinary soil. The more serious degradation degradation of vegetation, the fewer the number of the microbial of permafrost soils, and the lower heat production. The research about the activity of permafrost and the relation between the microbial and the vegetation coverage have not been reported previously by microcalorimetry method.