Abstract
Horse serum, sodium chloride, and sucrose were investigated for effect on growth and colonial characteristics of staphylococcal L-forms, strain STA-EMT-1 produced at the authors' laboratory, in comparison with those of Escherichia coli L-forms.
1. The best growth of staphylococcal L-forms was obtained on a solid medium containing more than 5% horse serum. With a decrease in the concentration of horse serum, their growth turned to be worse, although slight growth was still noticed even on a medium containing no horse serum at all.
Colony forms grown on solid media containing different concentrations of horse serum were as follows: Colonies assumed a typical “fried-egg” configuration on a 10% horse serum medium. Each colony had a rather small dark central area with an indefinite border on a 3% horse serum medium. Colonies had no central dark area, and consisted of an irregular-shaped material on a 1% horse serum medium.
2. No growth of staphylococcal L-forms was observed in a medium with sucrose added as a stabilizer of osmotic pressure, while E. coli L-forms could grow in this medium.
3. The best growth of staphylococcal L-forms was obtained by addition of NaCl at a concentration more than 3%. With a decrease in NaCl concentration, their growth diminished. No growth was observed at a concentration of NaCl less than 1%. On a medium containing 5% NaCl colonies showed a typical configuration: On a medium containing 2% NaCl the central area became smaller in each colony.
From the results mentioned above, it is recommended for the isolation of staphylococcal L-forms to use a medium consisting of brain heart infusion, 10% horse serum, 5% NaCl, and 1% special agar.
