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Ecoenzymatic Stoichiometry of Microbial Organic Nutrient Acquisition in Soil and Sediment
Citation:
SINSABAUGH, R. L. AND B. H. HILL. Ecoenzymatic Stoichiometry of Microbial Organic Nutrient Acquisition in Soil and Sediment. NATURE. Macmillan Publishers Ltd., London, Uk, 462(7274):795-798, (2009).
Impact/Purpose:
The results identify the boundaries of microbial community response to environmental nutrient dynamics and show that heterotrophic microbial communities of diverse composition share a common functional organization.
Description:
Terrestrial soils and freshwater sediments contain reserves of organic carbon estimated at 1500 Pg and 0.2 Pg, respectively. Mineralization of this organic matter by heterotrophic microorganisms drives global carbon and nutrient cycles, controlling plant production and atmospheric composition. Ecoenzymes deconstruct plant and microbial cell walls, depolymerize macromolecules, and ultimately produce soluble substrates for microbial assimilation. The enzymatic degradation of biopolymers requires the synergistic interaction of several classes of enzymes. The mostly widely measured activities include BG, NAG, LAP and AP. The potential activities of these enzymes are frequently linked to rates microbial metabolism and biogeochemical process, and used as indicators of microbial nutrient demand. Analysis of ecoenzymatic C:N:P activity ratios supports the biogeochemical hypothesis that soil microbial communities are generally C limited, and extends the hypothesis that terrestrial communities tend to be N limited and aquatic communities P limited to include heterotrophic microbial communities. More fundamentally, the results identify the boundaries of microbial community response to environmental nutrient dynamics and show that heterotrophic microbial communities of diverse composition share a common functional organization. The approximate 1:1:1 functional C:N:P stoichiometry of these enzyme activities is metabolically significant because it indicates that the rates of supply of assimilable substrates from the respective C, N and P reservoirs are similar in magnitude. Our analyses show that the range of response for these models is similar for all ecosystems independent of microbial community composition.
