SUMMARYExamination of a variety of species of molds and yeasts, including those of the genusPichia, has revealed significant production of the hydrolytic enzymeα-galactosidase inPichia guilliermondii.Release of the enzyme in this ascosporogenous yeast was strongly affected by certain substrates such as melibiose and lactose, and soybean products, including casitone, soytone, and soybean-oil meal. Maximalα-galactosidase was detected in media containing lactose and the soytone product atpH 7. Enzyme production was stimulated by addition of metal salts to the culture broth.