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Abstract
Cells of a tetrathionate-reducing coliform organism growing in semi-anaerobic conditions gained no advantage from the presence of tetrathionate at 41°, but at lower temperatures (e.g. 34°) they grew much better with than without it. When freely supplied with oxygen, the cells grew about as well at 41° as at 34°. The adaptive formation of tetrathionase in washed suspension has already been shown to diminish with increase of temperature from 34° to 44°, whereas the activity of the enzyme when formed increases with temperature in this range; nitratase, on the other hand, is still actively formed at temperatures as high as 44°. It is clear that whatever factors may be necessary for adaptation, one of them is more sensitive to heat than either nitratase formation or the overall growth process.
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