Aerobic glycerol catabolism by Pediococcus pentosaceus isolated from wine

Glycerol catabolism was studied in Pediococcus pentosaceus N5p isolated from wine, growing on different glycerol concentrations in aerobic conditions. Enzymatic activities of the glycerol kinase and glycerol dehydrogenase pathways were detected but the levels demonstrated allow to establish that glycerol was mainly degraded by glycerol kinase pathway. The highest levels of the activities of this pathway were expressed at the lowest concentration of glycerol, decreasing with the increase in glycerol concentration in the growth media. Glycerol was transformed in d-lactate, acetate, diacetyl and 2,3-butanediol. The enzymatic activities involved in the formation of these products were also modulated by glycerol. NAD-dependent lactate dehydrogenases were not affected by glycerol. Diacetyl reductase and acetoin reductase were inhibited by glycerol, whereas NAD-independent lactate dehydrogenases, NADH oxidase as CoA-independent acetaldehyde dehydrogenase, and acetate kinase were stimulated. The behavior of the enzymatic activities was in conformity with the fermentation balances; we propose a probable pathway for glycerol catabolism in P. pentosaceus N5p.