Recovery of 13C from both sugars was highest in the Gram negative PLFA on both days, with a
maximum of 0.8%. Two of the Gram positive groups - Gram positive
I and actinomycetes e also showed elevated maximum incorporations
into their PLFAs of 0.2e0.4%. For most microbial
groups, significant differences between the recovery of 13C from
individual sugar positions were observed on both days. Glucose
13C-2 and ribose 13C-5 tracer had the highest recovery in most
microorganism groups. There was little to no incorporation of
glucose 13C-4 and ribose 13C-1 in all microorganisms' PLFAs. However,
due to differences in absolute tracer uptake, comparison of
position-specific 13C behavior between the microbial groups is
difficult. Therefore, the relative tracer 13C incorporation (divergence
index (DI)) is better suited for detailed comparison.