We used metabolic tracers and modeling to analyze the response of soil metabolism to a sudden temperature change from 4 to 20 °C. We hypothesized that intact soil microbial communities would exhibit shifts in pentose phosphate pathway and glycolysis activity as observed for individual microorganisms in pure culture, and that increased maintenance respiration at higher temperature would result in greater energy production and reduced carbon use efficiency (CUE). Two hours after temperature increase, respiration increased almost 10-fold. Although all metabolic processes were increased, the relative activity of metabolic processes, biosynthesis and energy production changed. Pentose phosphate pathway was reduced (17–20%), while activities of specific steps in glycolysis (51%) and Krebs cycle (7–13%) were increased. In contrast, only small but significant changes in biosynthesis (+2%), ATP production (−3%) and CUE (+2%) were observed. In a second experiment, we compared metabolic responses to temperature increase in soil from high and low elevations. The shift in activity from pentose phosphate pathway to glycolysis with higher temperature was confirmed in both soils, but the responses of Krebs cycle, biosynthesis, ATP production, and CUE were site dependent. Our results indicate that 1) in response to temperature, communities behave biochemically similarly to single species and 2) our understanding of temperature effects on CUE, energy production and use for maintenance and growth processes is still incomplete.
Peer Reviewed Literature: Effect of temperature on metabolic activity of intact microbial communities: Evidence for altered metabolic pathway activity but not for increased maintenance respiration and reduced carbon use efficiency
Soil Biology and Biochemistry, June 2011