CITRATE METABOLISM IN 16 LEUCONOSTOC-MESENTEROIDES SUBSP MESENTEROIDES AND SUBSP DEXTRANICUM STRAINS

Citrate metabolism was studied in non-growing cells of Leuconostoc mes enteroides subsp. mesenteroides and subsp. dextranicum with respect to energetics, formation of degradation products and stoichiometry. The use of selective ionophores and uncoupler showed that citrate utilizat ion was coupled to the proton motive force generated by ATP hydrolysis . Differences in citrate metabolism observed in 20 Leuconostoc strains were related to strains but not to the species or subspecies studied. Citrate metabolism was stimulated by glucose up to a concentration of 25 mmol l(-1) and decreased at higher concentrations. The main degrad ation products resulting from the co-metabolism of citrate (10 mmol l( -1)) and glucose (2 mmol l(-1)) were acetate, lactate and pyruvate. On ly four Leuconostoc strains produced low levels of acetoin and diacety l. No strains produced ethanol or acetaldehyde. Citrate degradation ab ility was stable for at least 130 generations in 81% of the Leuconosto c strains.