Oxygen effect on lactose catabolism by a Leuconostoc mesenteroides strain: modeling of general O2-dependent stoichiometry

Florence Plihon (1) , Patricia Taillandier (1) , Pierre Strehaiano (1)

1 LGC - Laboratoire de Génie Chimique

Lactose metabolism of a Leuconostoc mesenteroides strain was studied in batch cultures at a pH of 6.5 and 30 degrees C in 10 L of a modified MRS (De Man, Rogosa, Sharp) broth. The end products of this heterolactic bacterium were D-lactate, acetate, ethanol, and carbon dioxide. To test the effect of oxygen on their synthesis, the medium was sparged with different gases: nitrogen, air, and pure oxygen. When oxygen was available, oxygen uptake occurred, which caused a modification in acetate and ethanol production but not in lactate or carbon dioxide production; acetate plus ethanol together were produced in constant amounts, which were independent of the level of aeration. The influence of oxygen on end-product formation could be summed up by the general equation: lactose + x O(2) --> 2 D-lactate + (x + 0.1) acetate + (2 - x) ethanol + 2 CO(2). Maximal oxygen uptake (x = 2) was reached under a 120 L/h flow rate of pure oxygen. In addition, this equation provided useful information on the possible pathway of galactose catabolism by a heterofermentative microorganism.

Mots clés: Leuconostoc mesenteroides; Lactose catabolism; Oxygen; Stoichiometry

Domaines: Génie chimique; Génie des procédés

Florence Plihon, Patricia Taillandier, Pierre Strehaiano. Oxygen effect on lactose catabolism by a Leuconostoc mesenteroides strain: modeling of general O2-dependent stoichiometry. Biotechnology and Bioengineering, 1996, 49 (1), pp.63-69. ⟨10.1002/(SICI)1097-0290(19960105)49:1<63::AID-BIT8>3.0.CO;2-R⟩. ⟨hal-02143237⟩