Filamentous fungal growth assay: Correlation between [U-14C] glucose uptake and dry weight determinations

Abstract
The filamentous fungus T. mentagrophytes was grown in [U-14C] glucose supplemented nutrient broth. Growth was monitored in 200 .mu.l microcultures and 5 ml macrocultures by measuring the incorporation of 14C into trichloroacetic acid-insoluble macromolecules and in macrocultures by dry weight determination. Adjustment of the specific activity of the [U-14C] glucose medium supplement from 1080 .mu.Ci/mmol to 108 .mu.Ci/mmol decreased the rate of isotope uptake and prolonged availability so that growth beyond 36 h could be monitored radiometrically. The dry mycelial weight of the fungus was directly proportional (r = 0.995) to the amount of isotope incorporated. Isotope uptake in microcultures and macrocultures was kinetically identical. The uptake of 14C by T. mentagrophytes can be used to monitor fungal growth accurately in both macrocultures and microcultures.