SUMMARY: Lactate, ethanol and butanediol were excreted when was exposed to severely restricted aeration. This indicated the presence of dehydrogenases which are not normally present in aerobically grown cultures of this strictly aerobic bacterium. When grown in the presence of measurable dissolved oxygen concentrations. strain N9A and a double mutant defective in the formation of poly-3-hydroxybutanoic acid and in the utilization of 3-hydroxybutanoate did not synthesize alcohol, lactate or butanediol dehydrogenases. However, when bacteria were subsequently incubated for 10 to 25 h under restricted aeration conditions that permitted respiration rates of only about 3 to 15% of the maximum value, the above enzymes were formed with specific activities up to 0·75 μmol min (mg protein). The identity of metabolites excreted as well as the nature of the enzymes formed could be correlated with the distinctive relative respiration rates enforced on the bacteria during incubation.

The results indicate that contains genetic information which is not expressed under ordinary cultural conditions. The significance for retention of the dormant genetic material in strictly aerobic bacteria is discussed.


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error