Dynamic utilization of low‐molecular‐weight organic substrates across a microbial growth rate gradient

Aim Low‐molecular‐weight organic substances (LMWOSs) are at the nexus between micro‐organisms, plant roots, detritus, and the soil mineral matrix. The nominal oxidation state of carbon (NOSC) has been suggested as a potential parameter for modelling microbial uptake rates of LMWOSs and the efficiency of carbon incorporation into new biomass. Methods and Results In this study, we assessed the role of compound class and oxidation state on uptake kinetics and substrate‐specific carbon use efficiency (SUE) during the growth of three model soil micro‐organisms, a fungal isolate (Penicillium spinulosum) and two bacterial isolates (Paraburkholderia solitsugae, and Ralstonia pickettii). Isolates were chosen that spanned a growth rate gradient (0.046–0.316 h−1) in media containing 34 common LMWOSs at realistically low initial concentrations (25 μM each). Clustered, co‐utilization of LMWOSs occurred for all three organisms. Potential trends (p