[Relation of bacitracin synthesis and manganese content in Bacillus licheniformis: antibiotic production in colonies forming on media with high levels of Mn2+].

Population of B. licheniformis is not homogeneous with respect to its sensitivity to Mn2+. Active bacitracin producing cultures with high and low sensitivity to exogenic manganese are described. In media containing high sublethal concentrations of Mn2+ there were detected two types of bacitracin-producing colonies i.e. light and dark differing likely in the mechanisms of their cell protection from the metal excess. Since bacitracin production did not always correlate with sensitivity to Mn2+ at the level of the colony formation the use of Mn2+ as a selective factor for isolating inactive strains of B. licheniformis is of low efficiency.