GENETIC NATURE OF STABLE L FORMS OF SALMONELLA PARATYPHI

Abstract

Up to 50% of the cells of Salmonella paratyphi B can be converted to a heritably altered state, the L form, by temporary treatment with penicillin. The heritable loss of the ability to form a bacillary colony ("commitment") can occur in the absence of cell division. Agar, serum, and a complex medium are not required for commitment but are necessary for propagation of the L forms. Stable salmonella L forms give rise to rare revertants to the bacillary form, which can again give rise to stable L forms. It is concluded that gene alterations are not involved in either commitment or reversion, and that the inherited damage is sustained and propagated in the bacterial membrane. Various new methods used in handling L forms, and several properties of salmonella L forms, i.e., occurrence of reverting and stable types, reactions with bacteriophages, and behavior of penicillin-resistant types, are described.