Products of Anaerobic Glycerol Fermentation by Streptococci faecalis

Abstract

Glycerol fermentation by streptococci has been found to occur only in the presence of external hydrogen acceptors, the main reaction being: glycerol [forward arrow] lactic acid + 2H. Some strains, as described previously, can use only oxygen as a hydrogen acceptor, the other product being H2O2. Other strains, as reported in this study, can use an unidentified substrate in yeast extract as H acceptor. This can be replaced by famaric acid, in which case the main reaction becomes: glycerol + fumaric acid [forward arrow]lactic acid + succinic acid. This reaction requires a higher riboflavin level than is necessary or glucose fermentation, very probably for hydrogen transport to fumaric acid. With an excess of fumarate, oxidized products are formed.