The lactose-negative yeast Rhodotorula glutinis 22P and the homofermentative lactic acid bacterium Lactobacillus helveticus 12A were cultured together in a cheese whey ultrafiltrate containing 42 g L-1 lactose. The chemical composition of the caroteno-protein has been determined. The carotenoid and protein contents are 248 micrograms g-1 dry cells and 48.2% dry weight. Carotenoids produced by Rhodotorula glutinis 22P have been identified as beta-carotene 15%, torulene 10%, and torularhodin 69%. After separating the cell mass from the microbial association, the exopolysaccharides synthesized by Rhodotorula glutinis 22P were isolated from the supernatant medium in a yield of 9.2 g L-1. The monosaccharide composition of the synthesized biopolymer was predominantly D-mannose (57.5%).