A PROCEDURE FOR DEMONSTRATING THE PRESENCE OF CAROTENOID PIGMENTS IN YEASTS

Abstract

This investigation was undertaken to improve existing methods for the extraction of carotenoid pigments from yeasts. Procedures adaptable to the routine screening of potential pigmented spp., and to the detn. of the nature of the extracted carotenoids were desired. The yeasts were grown on different cultural media and the cells subjected to a variety of the extraction treatments. It was observed that when the pigmented yeasts were grown on solid or liquid media which were highly buffered or contained such materials as peptone or casein hydrolysate, the pigments could only be released for subsequent extraction with acetone, by the use of rather strong concns. of acid and heat. Saponification procedures designed to release the pigments were completely ineffective. Unfortunately, acid treatments destroyed or measurably altered the character of the pigments obtained from certain yeast spp., particularly the yellow-pigmented types. However, when the test yeasts were grown in Wickerham''s synthetic broth (containing 2% glucose) for 72 hrs. on a rotary shaker, the pigments were readily and directly extracted from the cells with cold acetone. The pigments could then be transferred to petroleum ether for characterization by chromatographic and spectrophotometric methods. Apparently, the character of the culture medium has not heretofore been shown to be a factor influencing extractability of carotenoids from yeasts. Results are reported for 20 known spp. and vars. of yeasts in the genera Rhodotorula and Torulopsis. as well as a considerable number of pigmented types currectly being identified.