Abstract
Summary
Seven species of human T-mycoplasmas that grow in Fraction A and 20 μg urea/ml died when the urea was omitted. Two species would not grow in Fraction A broth containing 10 μg/urea/ml. The other five strains grew in broth containing 10 μg/urea/ml and were adapted by serial passage in broth containing decreasing concentrations of urea to grow in broth containing 2.5 μg/ml urea, but not in broth containing 1.25 μg/ml. Therefore the minimal urea requirement is not the same for the growth of all strains of T-mycoplasmas. In exponential phase broth cultures, urease was detected only intracellularly, none being found in the medium.
We wish to thank Ms. Marsha Trocola for her excellent technical assistance. This research was supported by grant number RO1 A108282 from the Institute of Allergy and Infectious Diseases.
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