Carbohydrate Content of Fungal Humic Acid-type Polymers (Melanins)1
- L. F. Linhares and
- J. P. Martin2
The carbohydrate contents of a variety of fungal humic acid-type melanins ranged from 1.1 to 5.9%. Values were 1.7 to 2.6% for soil humic acids and 0.4% for Leonardite peat humic acid. Fungal culture medium polymers not precipitated by acid and fungal cells contained from 12 to 55% carbohydrates. The uronic acid content of all products was very low, ranging from essentially zero (not detected) to 1.1%. Stachybotrys atra was the only fungus where uronic acids were detected in all samples. Uronic acids were, however, present in all soils, the values ranging from 0.3 to 0.4%. Recovery of uronic acids after acid hydrolysis using galacturonic acid as a check gave low values. The necessity of eliminating interferring substances before the colorimetric determination of sugars and uronic acids in soil and fungal polysaccharide hydrolysates was demonstrated. Thin-layer chromatography of concentrated hydrolysates from the humic acid-type fungal melanins and soil humic acids showed the presence of glucose, galactose, mannose, and xylose in most of the samples. A mass spectrum of the pyrolysis fragments of Aspergillus glaucus sp. humic acid-type polymer showed definite series peaks related to polysaccharides, the most prominent, however, were related to proteins and phenolic substances.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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