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Abstract
Campylobacter sputorum subspecies bubulus was grown in batch cultures in which the dissolved oxygen tension (d.o.t.) was maintained at various constant levels. At a range of d.o.t. from 0.002 to 0·05 atm, which allowed good growth (mean generation time approximately 1·5 h), l-lactate was preferentially consumed before d-lactate. l-Lactate oxidation was accompanied by equimolar acetate production during exponential growth. A value for Y l-lactate (g dry weight bacteria per mol l-lactate) of 54 was determined. Net acetate production stopped when C. sputorum started to use d-lactate after consumption of l-lactate. When a culture growing exponentially at the expense of l-lactate was shifted from a d.o.t. of 0·02 atm to a d.o.t. of 0·15 atm, growth was impaired, and l-lactate consumption and corresponding acetate production diminished. This decrease correlated with a loss of lactate dehydrogenase activity after the shift. Campylobacter sputorum appeared to possess cytochromes of the b- and c-type and a carbon monoxide-binding pigment. Evidence is given that the principal site of oxygen damage is lactate dehydrogenase rather than the cytochrome chain.
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