Abstract
Summary
L phase growth of bacteria was produced by exposing growing organisms to high concentrations of penicillin and D-cyclo-serine. Of 96 bacterial strains examined, 16 produced L growth which could be maintained in serial subculture. Exposure of bacteria to cycloserine gave L phase growth only in strains which also produced L growth on exposure to penicillin. The penicillin and cycloserine sensitivities of the bacteria from which the L forms were isolated were compared with the sensitivities of the L forms. The concentrations of penicillin which inhibited L growth ranged from 2 to 1000 times the concentrations required for inhibition of bacterial growth. The concentrations of cycloserine required for inhibition of L phase growth were 4 to 60 times greater than those required for inhibition of bacterial growth. Mycoplasma exhibited marked resistance to both agents. The resistance of the L phase growth and Mycoplasma to penicillin and cycloserine is evidence to substantiate the role of these antibiotics in affecting bacterial pathways which synthesize the cell wall.
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