Hemolytic and hemoxidative activities in Mycoplasma penetrans

Mycoplasma penetrans is a newly isolated Mollicute from the urine of patien ts infected with human immunodeficiency virus that demonstrates the capacit y to adhere to and invade human cells. A previous report, based on assays w ith mouse red blood cells (RBCs), indicated that M. penetrans lacked hemoly tic activity. In our studies, we incubated different isolates of M, penetra ns with various RBC species and observed hemolytic zones surrounding indivi dual mycoplasma colonies. All M. penetrans strains displayed hemolysis afte r 2 to 3 days of incubation. Hemolytic activity diffused from single coloni es, eventually causing complete lysis, Hemolysis was most pronounced with s heep RBCs, followed by horse, chicken, and human cells. Furthermore, hemoly tic activity was demonstrable in both intact mycoplasma cell preparations a nd spent culture supernatant, However, unlike intact mycoplasmas, the hemol ytic activity in the supernatant was dependent on the reducing agent, cyste ine, In addition to hemolysis, a brown precipitate was closely associated w ith mycoplasma colonies, suggesting oxidation of hemoglobin. Absorption spe ctra indicated that hemoglobin was oxidized to methemoglobin, and the addit ion of catalase demonstrated H2O2-mediated hemoxidation, Other experiments suggested that hemoxidation enhanced total hemolysis, providing the first e vidence of both hemolytic and hemoxidative activities in M, penetrans.