Production of carotenoids by Phaffia rhodozyma grown on media composed of corn wet-milling co-products

Abstract

Natural isolates of the carotenoid-producing yeast Phaffia rhodozyma were analyzed for their ability to grow and to produce carotenoids in culture media composed exclusively of co-products of corn wet-milling for fuel ethanol production. Five P. rhodozyma strains were tested for biomass produced (dry weight) and carotenoid yield. Six co-products were examined, ranging in cost from approximately $0.02 per kg to $0.11 per kg, all less expensive than conventional or agricultural growth substrates previously tested. The three co-products allowing the greatest accumulation of biomass and carotenoids by P. rhodozyma were thin stillage (TS), corn condensed distiller's solubles (CCDS) and corn gluten feed (CGF). Of the medium compositions tested, 10-15% CGF, 70% TS and 6-8% CCDS generally allowed maximum carotenoid production. Cultures grown in these three media produced up to 65%. 148% and 104% of the carotenoid yield per ml of yeast extract/malt extract (YM) cultures, respectively. Under the conditions tested, this was at an approximate medium cost of $0.67 per g carotenoids for CCDS and $0.73 per g for CGF as compared to $385.00 per g for YM. These results indicate that certain co-products of corn wet-milling can serve, at the appropriate concentration, as efficient, economical substrates for growth and carotenoid production by Phaffia rhodozyma. © 1995 Society for Industrial Microbiology.