Oxygen effect on lactose catabolism by a Leuconostoc mesenteroides strain: Modeling of general O2-dependent stoichiometry
✍ Scribed by Florence Plihon; Patricia Taillandier; Pierre Strehaiano
- Book ID
- 102650743
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 559 KB
- Volume
- 49
- Category
- Article
- ISSN
- 0006-3592
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✦ Synopsis
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 o-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 0, + . 2 D-lactate + (x + 0.1) acetate + (2x ) ethanol + 2 CO,. 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.