beta-Ionone vapour has been shown to cause an increase in the more saturated carotenes and a decrease in the less saturated carotenes of Rhodotorula glutinis. Lycopersene (dihydrophytoene) has been proposed as a precursor to phytoene. Attempts were made to isolate lycopersene from beta-ionone-treated cultures of R. glutinis. 2. Large samples of beta-ionone-treated cultures were examined for the presence of lycopersene. Spots were detected on silicic acid plates that could not be differentiated from synthetic lycopersene on the basis of column and thin-layer chromatographic separations and staining techniques. The lycopersene-like substance could be obtained from non-treated pigmented yeast as well as baker's yeast. 3. An extraction of bacterial-grade yeast extract also yielded a lycopersene-like substance. The extracts of R. glutinis cells cultured on media not containing yeast extract did not contain the lycopersene-like compound. 4. No significant carbon was incorporated into the lycopersene zone from (14)C-labelled mevalonate, acetate and glucose by R. glutinis and baker's yeast. 5. These results indicate that compounds may exist with chromatographic properties similar to lycopersene, but that lycopersene could not be detected in either a pigmented or a non-pigmented yeast.
