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Vector analysis of ecoenzyme activities reveal constraints on coupled C, N and P dynamics
Citation:
Moorhead, D., R. Sinsabaugh, B. Hill, AND M. Weintraub. Vector analysis of ecoenzyme activities reveal constraints on coupled C, N and P dynamics. SOIL BIOLOGY AND BIOCHEMISTRY. Elsevier Science Ltd, New York, NY, 93:1-7, (2016).
Impact/Purpose:
• We developed a quantitative method for estimating resource allocation strategies of microbial communities based on the proportional activities of four, key extracellular enzymes, glucosidase (BG), leucine aminopeptidase (LAP), N-acetylglucosaminidase (NAG) and acid (alkaline) phosphatases (AP). • Proportional activity of C vs. N acquiring enzymes (BG/[BG+NAG+LAP]) was plotted against C vs. P acquiring enzymes (BG/[BG+AP]). • We then calculated the length and angle of the vector created by connecting a line between the plot origin and point represented by these proportions; the length quantifies relative C vs. nutrient limitation and the angle quantifies the relative P vs. N limitation. • Analyses of large data sets obtained from soil, periphyton and aquatic sediments revealed that logarithmic, arcsine, arcsine-square-root and logit transformations did little to improve the statistical distribution of data over raw proportions. • Vector characteristics of enzyme activity loci are much easier to interpret for raw proportions than when these data have been previously transformed.
Description:
We developed a quantitative method for estimating resource allocation strategies of microbial communities based on the proportional activities of four, key extracellular enzymes, 1,4-ß-glucosidase (BG), leucine amino-peptidase (LAP), 1,4-ß-N-acetylglucosaminidase (NAG) and acid (alkaline) phosphatases (AP). The proportional activity of C vs. N acquiring enzymes (BG/[BG+NAG+LAP]) was plotted against C vs. P acquiring enzymes (BG/[BG+AP]). We then calculated the length and angle of the vector created by connecting a line between the plot origin and point represented by these proportions; the length quantifies relative C vs. nutrient limitation and the angle quantifies the relative P vs. N limitation. Analyses of large data sets obtained from soil, periphyton and aquatic sediments revealed that logarithmic, arcsine, arcsine-square-root and logit transformations did little to improve the statistical distribution of data over raw proportions. More importantly, the vector characteristics of enzyme activity loci are much easier to interpret for raw proportions than when these data have been previously transformed. Analyses of terrestrial communities revealed the importance of using consistent methods, i.e., omitting NAG analyses for an acidic soil led to overestimates of P limitations, and the importance of understanding the nature of the system, i.e., soils of the Antarctic Dry Valleys had low BG activities, likely because there is little to no local production of cellulose. In addition, vector characteristics may not reflect differences in individual enzyme activities between sites or over time because the latter can result from changes in microbial biomass pool size and/or level of activity without necessarily altering the overall resource acquisition strategy.
