Trichomonas vaginalis is an anaerobic parasite causative of trichomoniasis, an infection of the genitourinary tract. The most common pathogenic protozoan infection of humans, Trichomonas vaginalis also retains many enzymes that catalyze reactions important to the study of protein function. Although Tricho-monas vaginalis lacks the mitochondria and other cytochromes necessary to carry out oxidative phosphorylation, it can alternatively capture nutrients by phagocytosis. Trichomonas vaginalis also maintains energy requirements through glycolysis, including the conversion of pyruvate and malate to hydrogen and acetate in the hydrogenosome, a specialized organelle. Trichomonas vaginalis is among the most persistent protozoan trophozites, able to survive for up to 24 hours in urine, semen or even water samples.