Testing POXC with glucose and lignin additions to a soil sample result in no significant difference. Therefore I assume it would be hard to relate POXC values with the predominance of fungal or bacterial pathways in C breakdown.
Reactive carbon is linked to a number of soil processes, including microbial biomass growth/activity and nutrient cycling . Researchers have found that POxC is significantly related to MBC and in few cases SOC and, thus, may be equally well suited to track management practices that promote C sequestration. For more tails consult https://www.nrcs.usda.gov