THE QUESTION OF THE SYNTHESIS OF THIAMIN BY THE CILIATE, GLAUCOMA PIRIFORMIS

Abstract

G. piriformis has been maintained in a medium containing "vitamin-free casein" and certain salts through 28 serial transfers. Casein soln. without added salts failed to support growth of the ciliates. The effects of thiamin, added to the salted casein medium, were comparable to those previously observed in media known to contain thiamin, and were quite different from the effects noted in dethiaminized and depleted media. Dethiaminized casein medium, with added salts and thiamin, supported growth, but was inadequate without the thiamin supplement. The thiazole and pyrimidine components of thiamin failed to replace added thiamin, and produced no significant effect either in dethiaminized medium or in salted casein medium. No evidence was obtained for the synthesis of thiamin by G. piriformis.