Enzymically and Physically Induced Inheritance Changes in Bacillus Subtilis.

When a culture of Bacillus subtilis strain 168 is treated with a solution of crystalline lysozyme, the bacteria pass through an osmotically sensitive bacillary phase to the protoplast stage. All of the protoplasts can be recovered as L-colony-forming elements on complex or chemically defined osmotically stabilized agar media. Protoplasts or L-bodies can be propagated in the L-state indefinitely or can be mass-reverted to the bacillary state by altering medium ingredients. In particular, several D-amin acids and soft agar inhibit reversion to the bacillary state, while hard agar and 30 per cent gelatin media induce reversion. Reversion in 30 per cent gelatin is often 100 per cent efficient and begins within five hours after plating. Penicillin-induced L-forms of B. subtilis differ from the bacillary form in their resistance to penicillin and seem to be identical to the lysozyme-induced L-forms. Their induction and resistance behavior constitutes an instance of Lamarckian inheritance. The conversion of bacteria to the L-state is attributed to the loss of a primer for cell-wall formation and cell division, while reversion is thought to be due to reinitiation of this primer. The primer is probably associated with the cell membrane. Its possible nature and parallels between the present inheritance system and previously described systems are discussed.