Methionine and the Formation of Pigment by Yeasts

Abstract

YEAST 47 ¹ grows well in a defined salts–glucose–ammonia medium, containing p-aminobenzoic acid, biotin, pantothenic acid and inositol². This medium, supplemented with 500 µgm. of L- (or 1,000 µgm. of DL-) methionine per ml., but containing suboptimal concentrations (0.003–0.04 mµgm./ml.) of D-biotin, yields yeast crops after 72–96 hr. at 28° which are unusual in that they are pink in colour. Other conditions being suitable, the colour is not formed (1) if any other amino-acid is substituted for methionine; (2) if the concentration of D-biotin is raised to 0.08 mµgm./ml.; (3) in the presence of optimal biotin, but suboptimal pantothenate, p-aminobenzoic acid or inositol. Formation of the pink pigment is thus associated with the presence of methionine and with a relative deficiency of biotin.