Microbiological evaluation of protein quality with Tetrahymena pyriformis W

Abstract

A procedure for assay of the nutritive value of proteins using Tetrahymena pyrlformls-W count after 4 days'' Incubation as a simple criterion is described. Modifications of the cultural conditions Included a reduction in the amount of phosphate in the basal medium and adjustment of meal suspension to pH 8[center dot]2 before autoclaving. For assays of protein concentrates and mixed animal feeding-stuffs the N level In the medium was reduced to 0E3 mg/ml. Glucose was a more suitable energy source for routine assays than starch. The nutritive value of Individual protein types (especially fish meals and meat meals) varied widely. Typical improvements in the nutritive value of certain vegetable proteins when supplemented with lysine and methlonine were observed with the simplified procedure.