Some enzymic activities and chemical properties of the mesosomes and cytoplasmic membranes of Bacillus licheniformis 6346.

1. The liberation of the vesicles of the mesosomes from protoplasts of Bacillus licheniformis strain 6346 is controlled by the Mg(2+) concentration present during the removal of the walls by lysozyme. 2. The functioning of the cytoplasmic membranes is also critically controlled by the Mg(2+) concentration. 3. The isolated mesosomes and the cytoplasmic membranes differ in their enzymic activities. Both succinate dehydrogenase and NADH oxidase activities are very low or absent from the mesosomes. 4. The cytoplasmic membranes can also be separated into materials of different density. 5. Distribution of the membranes between these fractions is controlled by the Mg(2+) concentration and the growth conditions of the microorganisms.