Anthranilic acid and 3-indolyl-propan-1,2-diol as precursors of photorubin in Saccharomyces

Summary The formation of photorubin, the orange-red pigment produced by Saccharomyces, is due to a photochemical reaction between anthranilic acid and an indole derivative identified with 3-indolyl-propan-1,2-diol. These two compounds are excreted into the medium by strains partly or completely requiring pyridoxine which are grown in the presence of a suboptimal amount of this vitamin. If pyridoxine is added to the growth medium in amounts either sufficient or exceeding the needs of the cells (over 50 g per liter), or if the strain is auxo-autotrophic, a secretion of hypoxanthine occurs.