Growth and division of protoplasts of Bacillus megaterium and inhibition of division by penicillin.

Protoplasts of Bacillus megaterium grew well and divided in nutrient broth containing 0.5 m NaCl as the stabilizer. Protoplasts also grew when sucrose or succinate was used instead of NaCl; however, no division phenomena were observed. The sequence of growth and division was similar to the results obtained by McQuillen. Protoplasts enlarged from 1.8 to 3.5 mu in diameter, and then a small protuberance formed in the enlarged cells. The nodules enlarged until eventually symmetrical dumbbell-shaped bodies were formed, which then separated into two daughter protoplasts having a diameter of about 2.5 mu. Deoxyribonucleic acid and ribonucleic acid were halved during division. Penicillin inhibited the division of protoplasts, though the growth was not influenced by the drug. Membrane-bound amino sugar content was considerably reduced when the cells were grown in the presence of penicillin. These results suggest that organized murein formed on the protoplasts membrane may play an important role in the septation process.