Studies in carotenogenesis. 2. Carotene production by Phycomyces blakesleeanus: the effect of different amino-acids when used in media containing low concentrations of glucose

In a previous investigation (Garton, Goodwin & Lijinsky, 1951) it was shown that, using a medium containing 3 % (w/v) glucose, carotene synthesis in Phycomyce8 blakeleeanu8 was independent of the amino-acid used as the nitrogen source with the exception that glycine enhanced carotene produc- tion. Amongst the amino-acids which had no effect was L-valine, from which a hypothetical five-carbon building unit such as P-methylcrotonaldehyde