Carbohydrate Nutrition of Rhizopus suinus

Abstract

1. Extraction of dextrose, levulose, galactose, and sucrose with acetone, alcohol, and ether resulted in increased mycelial production by Rhizopus suinus. 2. Extraction of dextrose with alcohol and ether resulted in increased mycelial production by this fungus. The increase was not so great as with the acetone-alcohol-ether extraction. 3. Recrystallization of dextrose from 80 per cent alcohol resulted in growth augmentation of about the same magnitude as that which resulted from the acetone-alcohol-ether treatment. 4. The presence of vitamin B1 (thiamin, aneurin) in reagent-grade dextrose was shown by the thiochrome oxidation method. Removal of traces of vitamin B1 from the sugars during the extraction process is possibly the cause of the growth phenomena. 5. The extract of dextrose contains a substance which, when concentrated by evaporation, promotes the vegetative growth of R. suinus if it is added to the culture medium. The substance was demonstrated, by growth experiments in which the nutrient solution was supplemented with the ash obtained from the unpurified dextrose, to be an ash constituent. 6. Under the conditions of the extraction, the removal of vitamin B1 would be more extensive than the removal of the ash constituents, the influence of the removal of the thiamin consequently being more effective in increasing the growth of R. suinus than the removal of the small amount of ash constituents in decreasing the growth of the organism. When the extract is concentrated, however, the influence of the ash element(s) on mycelial production is much greater than the influence of the vitamin B1, and the result is growth augmentation.