PERFORMANCE AND MORPHOLOGY OF KLUYVEROMYCES FRAGILIS AND RHODOTORULA GRACILIS GROWN IN COTTAGE CHEESE WHEY

Abstract

The overall objectives of this research were to find practical methods of cottage cheese whey disposal, and economical methods of recovering usable products from the whey. The specific purposes of this study were: (a) to determine whether Kluyveromyces fragilis could reduce the COD of cottage cheese whey more efficiently than in previous trials, (b) to attempt adaptation of Rhodotorula gracilis to lactose, and (c) to describe the morphology of the adapted Rh. gracilis culture. K. fragilis reached maximum cell numbers in approximately 7 h, with initial inocula of 1 × 108 cells/ml. At this rate of inoculation, the COD of cottage cheese whey was reduced 82 ± 2% in 10–11 h, and 93 ± 2% in 24 h, a greater reduction than reported by most authors. Rh. gracilis was adapted to utilize lactose as its sole carbon source by successive transfers on lactose agar. Photomicrographs of this adapted Rh. gracilis culture showed morphology similar to that reported in the literature when the yeasts had been grown on other media.