[Isolation of unbalanced growth forms from Listeria and their ultrastructure]

As the result of the action of penicillin, LiCl and UV irradiation on Listeria culture in the logarithmic phase, unbalanced growth forms (UGF) were obtained. Their viability was determined by the number of colony-forming units per ml. In this investigation the action of the above factors in a single cultivation and in consecutive subcultures was studied. Viable UGF were obtained under the action of all the above factors. UGF obtained under the action of penicillin were found to convert easily into L-forms in the process of subculturing. On the contrary, UGF obtained under the action of UV irradiation and LiCl produced no L-forms and reverted easily when the action of these factors stopped. In all three cases the formation of UGF was accompanied by changes in the structure of the cell wall and, partially, the cytoplasmic membrane, but in each case these changes had different character.