The Urea Requirement and Urease Production of some Human Species of T-Mycoplasmas

Abstract

Seven species of human T-mycoplasmas that grow in Fraction A [broth] and 20 .mu.g urea/ml died when the urea was omitted. Two species would not grow in Fraction A broth containing 10 .mu.g urea/ml. The other 5 strains grew in broth containing 10 .mu.g urea/ml and were adapted by serial passage in broth containing decreasing concentrations of urea to grow in broth containing 2.5 .mu.g/ml urea, but not in broth containing 1.25 .mu.g/ml. 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 was found in the medium.