Acetate-Glyoxylate Medium for the Sporulation of Saccharomyces cerevisiae

S ummary : Studies on ascospore formation by Saccharomyces cerevisiae on sodium acetate agar with and without an addition of sodium glyoxylate showed that the rate of ascus formation was increased when glyoxylate was present. The final proportion of asci was not affected but, since cell multiplication (almost threefold) before ascus formation occurred only on the acetate-glyoxylate medium, on the basis of the number of asci/unit of inoculum the effect of glyoxylate was even more marked. If CO₂ was removed from the atmosphere around the cells, sporulation was strongly inhibited when the medium contained only acetate, but there was less inhibition when glyoxylate was present as well. Ascospores formed on the acetate-glyoxylate medium changed their staining properties after the third day. The majority then stained with safranin but not with malachite green.