Summary: At oxygen concentrations of less than 0·2 atm. formed only the ‘massive’ colony type on nitrogen-free agar media; the ‘thin’ colony type which predominates in air was absent. Only the ‘massive’ colonies reduced acetylene. The acetylene-reducing activity of samples from a nitrogen-fixing continuous culture was inhibited when the oxygen supply was increased, which suggests that the oxygen sensitivity previously reported during growth in nitrogen-free media is associated with the nitrogen-fixing process. Colonial dimorphism probably arises because only when the local oxygen concentrations on the agar surface are depressed can nitrogen fixation and subsequent growth to the ‘massive’ colony type take place.


Article metrics loading...

Loading full text...

Full text loading...

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