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Oxygen effect on lactose catabolism by a Leuconostoc mesenteroides strain: Modeling of general O 2 ‐dependent stoichiometry
Author(s) -
Plihon Florence,
Taillandier Patricia,
Strehaiano Pierre
Publication year - 2000
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/(sici)1097-0290(19960105)49:1<63::aid-bit8>3.0.co;2-r
Subject(s) - chemistry , oxygen , leuconostoc mesenteroides , lactose , carbon dioxide , oxygen tension , ethanol , sodium lactate , chromatography , biochemistry , food science , organic chemistry , lactic acid , bacteria , sodium , biology , genetics
Lactose metabolism of a Leuconostoc mesenteroides strain was studied in batch cultures at a pH of 6.5 and 30°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. © 1996 John Wiley & Sons, Inc.