BayCEER Workshop 2008

Application of kinetic respiratory analysis for monitoring of soil microbial communities under environmental impact

Kinetics of respiratory response of soil microbial communities growing on ample quantity of glucose and nutrients (NPK) were studied for different soils  using an automated continuous-flow system with infrared gas analyser. Soil respiration rate (v) varied with time (t) as:  v(t) = A + B * exp(µ^.t), where µ - specific growth rate of microorganisms, A - initial rate of non-growth respiration, B - initial rate of growth respiration. Best-fitted parameters of this equation described the slope of respiration curve (µ), duration of lag-phase, and the ratio between the growing and sustaining parts of soil microbial biomass. Significant increase in µ was observed for soil microbial communities (1) under long-termed organic or mineral fertilization as compared to non-fertilized soil; (2) in rhizosphere versus root-free soil; (3) under elevated versus ambient atmospheric CO₂ concentrations. Industrial contamination, soil pollution with lead resulted in strong decrease in microbial growth rates. The use of automated recording of soil respiration rate together with application of simple model for data description gives a qualitatively new information about the state of soil microbial community. This approach showed a good potential for soil ecological studies.