Microbial Metabolism in Soil at Subzero Temperatures: Adaptation Mechanisms Revealed by Position-Specific C Labeling.

Although biogeochemical models designed to simulate carbon (C) and nitrogen (N) dynamics in high-latitude ecosystems incorporate extracellular parameters, molecular and biochemical adaptations of microorganisms to freezing remain unclear. This knowledge gap hampers estimations of the C balance and ecosystem feedback in high-latitude regions. To analyze microbial metabolism at subzero temperatures, soils were incubated with isotopomers of position-specifically C-labeled glucose at three temperatures: +5 (control), -5, and -20°C.

Soil microorganisms can overcome respiration inhibition by coupling intra- and extracellular metabolism: C metabolic tracing reveals the mechanisms.

CO release from soil is commonly used to estimate toxicity of various substances on microorganisms. However, the mechanisms underlying persistent CO release from soil exposed to toxicants inhibiting microbial respiration, for example, sodium azide (NaN) or heavy metals (Cd, Hg, Cu), remain unclear. To unravel these mechanisms, NaN-amended soil was incubated with position-specifically C-labeled glucose and C was quantified in CO, bulk soil, microbial biomass and phospholipid fatty acids (PLFAs).