THE TRANSFORMATION OF TYPHOID BACILLI INTO L FORMS UNDER VARIOUS CONDITIONS

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Abstract
Freshly isolated strains of Salmonella typhosa produce L-type colonies abundantly on soft horse-serum agar plates containing high concns. of penicillin. The L-type colonies grow well with the highest concn. of penicillin tested, 10,000 U./ml. of the media. Carboxylmethoxylamine and glycine induce a similar transformation but only in a narrow range of concn. The L forms are only slightly more resistant to these agents than the bacteria. L forms start to develop from bacteria exposed to aureomycin and chloramphenicol, but their growth is arrested in the initial stages. The resistance of the L forms and of the bacteria to these antibiotics is about the same. The L forms are more sensitive to acriflavine and crystal violet than are the bacteria. L forms were obtained from typhoid bacilli that survived exposure to specific antibody and complement. Bacilli lysed with bacteriophage did not develop into L forms, but those that survived in lysed cultures were occasionally transformed into these forms. Sublethal injuries of various types induce transformation into L forms, and the development of the latter depends largely upon whether they are more or less susceptible than the bacteria to the particular injury. Certain of the injuries producing L transformation are encountered by the bacteria in their natural environment, suggesting that this phenomenon may occur in the natural life of bacteria.
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