The Fermentation of Glycerol by Streptococci

Abstract

Although glycerol has been used as a test substrate in studies of the fermenta-tion reactions of lactic acid bacteria the results obtained have not been com-pletely satisfactory. Orla-Jensen (1919), using the amount of titratable acidity produced as a criterion of fermentation, has reported only one-fourth to one-half as much acid formed from glycerol as from glucose under analogous conditions. In addition, cultures reported as non-glycerol-fermenters frequently gave slightly higher-titrations than controls in the basic medium without glycerol. Less acid production from glycerol than from other substrates has also been reported by Fred, Peterson and Davenport (1920). Among the workers who detected fermentation by decrease in pH, several have reported variable results and slight