Oxidative Metabolism and Absoicption Spectra O F Anaerobically Grown Yeast

Ever since Pasteur's work (1876) it has generally been believed that without oxygen yeast can either grow only to a limited extent, or not at all (Brown, , O j ; Windisch, '32 ; White and Munns, 51). The slight growth that was obtained occasionally under anaerobiosis was attributed to the traces of oxygen left in the medium. The careful work of Stier and his collaborators (Stier, Scalf and Brocliman, '50 ; Stier, Scalf and Peter, '50; Andreasen and Stier, '53, '54, '56) finally clarified this problem. They showed (1) that under strict anaerobiosis yeast cells stopped growing entirely when carried for several transfers in a synthetic medium containing all the previously known growth factors; (2) that a culture medium containing vegetable oils (e.g., 0.3% wheat germ oil) and high concentrations (6-70/0) of yeast extract permitted anaerobic growth to reach the same final cell density, about 400 X los cells/ml, as that reached in aerobic cultures ; and (3) finally they were able to identify two new growth factors, required for anaerobic growth only, ergosterol and longchain unsaturated fatty acids (like oleic acid). I n a synthetic medium supplemented with minute amounts of these substances, final cell densities of ca. 200 X lo6 cells/ml were ob-