Light microscopic investigations on lysozyme- and penicillin-induced morphological changes in Erysipelothrix rhusiopathiae and on propagation of its protoplast type L-form.

Although lysozyme and penicillin are different in their molecular action on cell wall murein they produce similar morphological changes in Erysipelothrix rhusiopathiae grown on agar media. 2,000--5,000 micrograms/ml lysozyme and 0.1--2 IU/ml penicillin induce filament formation. Filaments are able to divide in rods, which shows that only cross wall formation and separation are inhibited. Higher doses of lysozyme (10,000 micrograms/ml) and penicillin (less than 1 IU/ml) inhibit cell wall synthesis and induce L-form growth. The propagation of this protoplast type L-form was investigated by microphotographic series in phase contrast microscope during L-form induction and in the stable L-form state. In both cases L-form cells propagate by formation and growth of small granular elements of about 0.2--0.6 micrometers in diameter, which spread in different directions in the agar medium. The multiplication process may be explained by the plasticity and flexibility of the L-form cell and its cytoplasmic membrane and by the structural and functional interaction between the "folded chromosome" and the surrounding cytoplasm.