Enhanced Conversion of Lactose to Glycerol by Kluyveromyces fragilis Utilizing Whey Permeate as a Substrate

Kluyveromyces fragilis (CBS 397) is a nonhalophilic yeast which is capable of lactose utilization from whey permeate and high glycerol production under anaerobic growth conditions. However, the optimum yields of glycerol (11.6 mg/ml of whey permeate medium) obtained in this study occurred only in the presence of 1% Na₂SO₃ as a steering agent. The use of other concentrations of Na₂SO₃, as well as 5% NaCl and 1% ascorbic acid, had no or detrimental effects on cell growth, lactose utilization, and glycerol production. Glycerol yields were greater in cultures grown from a light inoculum of K. fragilis than in cultures in which a resuspended mass of cells was introduced into the medium. The results of this study suggest that this strain of K. fragilis may be useful commercially in the utilization of cheese whey lactose and the concomitant production of glycerol.