The composition of the cell wall of Aspergillus niger

Abstract

1. The cell-wall composition of Aspergillus niger has been investigated. Analysis shows the presence of six sugars, glucose, galactose, mannose, arabinose, glucosamine and galactosamine, all in the d-configuration, except that a small amount of l-galactose may be present. Sixteen common amino acids are also present. 2. The wall consists chiefly of neutral carbohydrate (73-83%) and hexosamine (9-13%), with smaller amounts of lipid (2-7%), protein (0.5-2.5%) and phosphorus (less than 0.1%). The acetyl content (3.0-3.4%) corresponds to 1.0mole/mole of hexosamine nitrogen. 3. A fractionation of the cell-wall complex was achieved, with or without a preliminary phenol extraction, by using n-sodium hydroxide. Though this caused some degradation, 30-60% of the wall could be solubilized (depending on the preparation). Analyses on several fractions suggest that fractionation procedures bring about some separation of components although not in a clear-cut fashion. 4. Cell-wall preparations were shown to yield a fraction having [alpha](D) approx. +240 degrees (in n-sodium hydroxide) and consisting largely of glucose. This was separated into two subfractions, one of which had [alpha](D)+281 degrees (in n-sodium hydroxide) and had properties resembling the polysaccharide nigeran; the other had [alpha](D) +231 degrees (in n-sodium hydroxide). It is suggested that nigeran is a cell-wall component.