Carbohydrate Nutrition of Rhizopus suinus

Abstract

Investigation of the effects of alcohol-ether extraction and of acetone-alcohol-ether extraction of dextrose, jevulose, galactose, and sucrose on the carbohydrate utilization of R. suinus showed that 2 types of materials are removed by the extraction: vitamin B1 and heavy metals. The vitamin was detd. by careful Oxidation to thiochrome and observation of the ultraviolet fluorescence of the latter. The effect of the heavy metals was detd. by expts. in which the sugars were ashed and the ash added in definite amts. to the nutrient solns. Vitamin B1 seems to be necessary for spore formation by R. suinus, but is slightly detrimental to the dry wt. production of the fungus. Addition of the ash elements of the sugars to the extracted sugars resulted in a greatly increased dry wt., but caused no increase in spore formation. Galactose is definitely superior to dextrose as a source of C and energy for R. suinus. Expts. on the carbohydrate utilization of fungi should be critically examined with special regard to the purity of the sugars used.