The fermentation of glycerol byClostridium butyricum LMG 1212t2 and 1213t1 andC. pasteurianum LMG 3285

SummaryIn batch culture on reiinforced clostridial medium strain-dependent product profiles from glycerol revealed unusual fermentation products such as propionate and n-propanol with Clostridium butyricum LMG 1213t1, and 1,3-propanediol with C. butyricum LMG 1212t2 and C. pasteurianium LMG 3285. Only the latter two strains were able to grow on glycerol in a minimal medium. Nicotinamide adenine dinucleotide (NAD+)-dependent dehydrogenase activities were detected with 1,3-propanediol and n-butanol as substrate (the latter only after a lag period) in cell-free extracts of C. butyricum LMG 1212t2 and with 1,3-propanediol, n-butanol and ethanol in cell-free extracts of C. pasteurianum LMG 3285. The data indicated the existance of a specific 1,3-propanediol dehydrogenase in both organisms. In a chemostat, C. butyricum LMG 1212t2 converted 65% of the glycerol supplied as sole carbon and energy source to 1,3-propanediol without H2 production. Increasing concentration of acetate in the inflow medium resulted in less 1,3-propanediol and more butyrate and H2 production. C. pasteurianum LMG 3285 converted somewhat more than half of the glycerol supplied as sole energy and carbon source to n-butanol with significant concomitant H2 production. This fermentation pattern was hardly affected by acetate as co-substrate.