Effect of maltose on glucoamylase formation by Aspergillus niger.

Low levels of glucoamylase are produced when Aspergillus niger is grown on sorbitol, but substitution of the latter by glucose, maltose, or starch results in greater formation of glucoamylase as measured by enzymatic activity. Both glucoamylase I and glucoamylase II are formed in a yeast extract medium; however, glucoamylase I appears to be the only form produced when ammonium chloride is the nitrogen source. Maltose or isomaltose (1.4 x 10(-4)m), but no other disaccharides or monosaccharides, dextrins, dextrans, or starches, stimulated glucoamylase formation when added to mycelia pregrown on sorbitol-ammonium salts. The induction of glucoamylase by maltose was independent of sulfate concentration but showed a dependency on low pH and the absence of utilizable carbon sources.