Influence of carbohydrates and polyols on L-lactic acid production and fatty acid formation by Rhizopus arrhizus.

Growth and L-lactic acid production on 24 different carbohydrates and polyols (glycerol, mannitol and sorbitol) by Rhizopus arrhizus CCM 8109 were determined. The D- but not the L-forms of xylose, fructose, galactose, mannose, glucose, cellobiose, maltose and sucrose and partially hydrolysed starch were converted to L-lactic acid. Changes in lipid formation and fatty acid composition were detected in biomass grown on the different sugars. In the presence of polyols, growth and considerable production of lipids were observed with little or no lactate production. Invertase was mainly associated with the mycelium during growth on sucrose, whereas glucoamylase and α-amylase were produced extracellularly during growth on starch.