Steroid requirements of trichomonads.

Abstract

SYNOPSIS. The steroid requirement of a Trypticase‐requiring strain, SLT, of Trichomonas gallinae on the Shorb‐Lund synthetic basal medium minus ribonucleic acid was fulfilled by cholesterol, 7‐dehydrocholesterol(provitamin D3), cholestanol (dihydrocholesterol), and to a lesser degree, by ergosterol (provitamin D2), β‐sitosterol and zymosterol acetate. Cholestanol was inhibitory at certain concentrations. All steroids were subsequently checked by gas chromatography. Only cholesterol and zymosterol acetate showed one peak, the others containing 2 to 4 peaks. Repurified cholestanol was active and showed no inhibition of growth, but repurified β‐sitosterol was inactive. The following were also inactive: diethylstilbestrol, estrone, dehydroepiandrosterone, progesterone, testosterone, desoxycorticosterone acetate, cortisone acetate, compound A, 5,6‐dihydro‐ergosterol, dihydroergosterol acetate, stigmasterol, sodium taurocholate, cholic acid, methyl desoxycholate, desoxycholic acid and methyl cholate. Precursors in cholesterol synthesis, acetate, mevalonic acid, mevalonic acid plus a liver extract and squalene were inactive in replacing cholesterol, although acetate is required for growth in the presence of cholesterol. Crystalline fat soluble vitamins, carotene, calciferol (vitamin D2), activated 7‐dehydrocholesterol (vitamin D3), menadione (vitamin K3) and tocopheryl acetate (vitamin E acetate) were inactive in replacing cholesterol.Trichomonas species PN from the pig's nose utilized cholesterol, 7‐dehydrocholesterol and the impure β‐sitosterol sample in a modified SL medium with acetate omitted. A reinvestigation of steroid requirements seems to be indicated when a completely synthetic medium and pure steroids are available.