Comparing PLFA and amino sugars for microbial analysis in an Upper Michigan old growth forest

Phospholipid fatty acid (PLFA) analysis and amino sugars analysis were compared with respect to their capacity to reliably indicate microbial biomass and gross community structure (e.g. fungi to bacteria ratio). We sampled three sets of soils beneath dominant canopy-tree species in an old growth forest and extracted them using both PLFA and amino sugars procedures. Amino sugars data had a lower coefficient of variation among sample replicates and therefore may be better for quantitative application compared to PLFA data. However, when considering microbial community structure, PLFA had an advantage over amino sugars due to its more straightforward interpretation. Finally, because each biomarker derives from different portions of the microbial biomass, a conversion factor between cell membrane PLFA and cell wall amino sugars may be valuable in understanding soil carbon cycling.