Studies on the Pyruvate and Carbohydrate Metabolisms by Lactic Acid Bacteria

The pentose isomerase of heterofermenters was found to have specific action on the substrate. Only L-arabinose was isomerized by L-arabinose isomerase and no inhibitory effect was demonstrated by the addition of D-isomer, and xylose isomerase acted on D-xylose, and L-xylose did not inhibit such activity. No ketose from glucose, mannose, galactose, L-xylose, D-arabinose, D-ribose and mannitol was produced by these heterofermenters. The equilibrium constants for D-xylose- and L-arabinose isomerases were 20_??_28% and 13_??_16% respectively, and this equilibrium was shifted to ketopentose in the presence of borate. Michaelis constants were found to be 2×10-2M for D-xylose isomerase and 5_??_10×10-2M for L-arabinose isomerase.