A Comparison of Glucosamine and Biovolume Conversion Factors for Estimating Fungal Biomass

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Abstract
Glucosamine content or biovolume of fungi cannot be used to estimate fungal biomass unless the ratio of these quantities to fungal mass is known. The interspecific and temporal variation was measured for 7 attributes of 3 salt-marsh fungi grown on damp Spartina alterniflora. Glucosamine (.mu.g) and biovolume (mm3 fresh) per mg dry weight, mg C and mg N were calculated. There were significant differences (P < 0.01) among species (Buergenerula spartinae, Fusarium sp., Phaeosphaeria typharum) and among ages (2, 4, 12 wk) for glucosamine. Glucosamine and biovolume per unit mass increased with age. There were significant correlations (P < 0.01) between glucosamine and biovolume conversion factors (r = 0.89) and between residual hyphal mass after amino sugar analysis and hyphal N content (r = -0.85). Glucosamine did not correlate as well with hyphal surface area (P < 0.05). Considering all species and ages, glucosamine content varied from 8.5-92.8 .mu.g GlcN mg-1 dry weight (23-299 .mu.g GlcN mg-1 C; 170-3094 .mu.g GlcN mg-1 N). It is necessary to know species-specific and age-specific biomass conversion factors to accurately estimate fungal biomasses using biochemical or direct-count quantification techniques.