Microbiological Evaluation of Protein Quality I. A Colorimetric Method for the Determination of the Growth of Tetrahymena Geleii W in Protein Suspensions ,

Abstract

A method is described for estimation of the growth of the protozoan, T. geleii W, in protein suspensions. The procedure involves a colorimetric determination of the red triphenyl-formazan formed by reduction of the colorless 2,3,5-triphenyltetrazolium chloride, a reaction effected by the respiratory enzymes of the organism. This method has been used in obtaining dose-response curves of the organism to the 10 “essential” amino acids—arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. The procedure has also been successful in reflecting the response of T. geleii to graded levels of 4 different proteins tested.