L-form induction from ten strains of group A streptococci of various serotypes was investigated under several conditions. Two strains of L-form induced were examined for bacteriological characteristics.
L-form induction from group A streptococci was successfully affected by addition of glycine to induction medium, as well as by anaerobic culture condition. In addition, serotypes of these organisms were proved to have some correlation with L-form induction. L-forms were induced easily from the strains of types 1 and 6, but with difficulty from the strains of type 4.
Two L-form strains induced from types 1 and 6 were transferred on agar medium for scores of generations. They could be transferred on penicillin-free agar medium, but after 17 transfers one L-form strain (from type 1) reverted to the parent strain.
After each of 5, 10, 20 and 30 transfers on the agar medium, the two L-form strains described above were examined on broth culture. Only after 30 transfers they began to grow in broth medium. They were subcultured successflly in the broth medium, and did not revert to the parent strains when they were transferred in penicillin-free broth medium.
Minimal growth units of these L-form strains passed through a membrane filter 0.2 micron in pore size.
The two L-form strains were more highly resistant to penicillin-G, a little more susceptible to erythromycin, chloramphenicol and josamycin, and apparently much more susceptible to tetracycline than their parent strains. The susceptibility of the reverted strain to these antibiotics was of the same order as that of the parent one.
One of the L-forms grown in the broth medium produced streptolysin-S. This production was not increased by the addition of yeast RNA to the broth medium.
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