A carbon balance on glycine and glucose in carotene synthesis.

In a previous paper (l), we reported on the incorporation of the methylene carbon of glycine in carotene in Phycomyces blakesleeanus and presented data suggesting that 8-aminolevulinic acid (ALA) had an effect similar to leucine in stimulating carotene production. We now present supplementary evidence on the correctness of the data dealing with labeled glycine by completing a carbon balance with inactive glycine and labeled sugar, together with further experiments on ALA. We had shown earlier (2) that, in a medium composed of glucose and yeast autolysate, the glucose carbon, comprising 90 per cent of the available carbon in the medium, accounted for less than 40 per cent of the carotene carbon. Subsequently, we reported (3) that incorporation of the or-carbon of leucine was below the 5 per cent level from a medium where the source of nitrogen was a mixture of leucine and asparagine.