Background: In spite of the fact that the standard test for nitrate reductase activity is negative for Mycobacterium avium, it can grow in a defined minimal medium with either nitrate (NO) or nitrite (NO) as sole nitrogen sources.
Methods: NO-and NO-reductase activities were measured in soluble and membrane fractions of aerobically grown cells of M. avium and those grown aerobically and shifted to anaerobiosis.