Journal article

Glycerol production by yeast fermentation of whey permeate

Yeast strains were examd. for their ability to produce glycerol, and Kluyveromyces marxianus NRRLY-665 was chosen for further optimization due to its comparatively high growth rate (0.15/h) and glycerol yield (9.5% by wt. on lactose) at 37 Deg and pH 7. Optimal conditions for glycerol formation were 30-37 Deg and pH 6-7. Increasing whey permeate concn. above the equiv. of 4.5% lactose decreased growth rate and cell prodn. and increased HOAc prodn. When SO32- was added throughout the fermn. to complex AcH before it could be converted to EtOH, 21% glycerol yield was obtained at 4.5% g free SO32-/L, pH 7, 20 Deg, and <50 mm Hg pressure, but at a much lower growth rate than in the absence of SO32- at 37 Deg. Several osmotolerant yeast strains were cultivated on regular and enzyme-hydrolyzed whey permeate at high NaCl concns. One of them, Pichia farinosa DSM 70362, did not produce glycerol from whey permeate but gave 4% yield on enzyme-hydrolyzed lactose. Osmotolerant yeast metabolized glycerol after glucose, at the same time as galactose, and before lactose. [on SciFinder (R)]


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