Effect of penicillin, growth phase, ultraviolet light, and ultrasonic vibrations on the ability of Proteus mirabilis to form L type colonies.

The literature on L forms of Proteus contains data derived from many cultural conditions and with different amounts of penicillin. It is difficult to evaluate conflicting reports unless the effect of environmental factors on the ability to form L type colonies can be put on a quantitative basis. This was done with the effect of media (Medill and O'Kane, 1954), and in the present paper attempts are reported to quantitate the effects of various other environmental factors. It is hoped that these data will help to elucidate the mechanism of L type colony formation.