title: Beta-carotene-rich carotenoid-protein preparation and exopolysaccharide production by Rhodotorula rubra GED8 grown with a yogurt starter culture.
abstract: The underlying method for obtaining a beta-carotene-rich carotenoid-protein preparation and exopolysaccharides is the associated cultivation of the carotenoid-synthesizing lactose-negative yeast strain Rhodotorula rubra GED8 with the yogurt starter culture (Lactobacillus bulgaricus 2-11 + Streptococcus thermophilus 15HA) in whey ultrafiltrate (45 g lactose/l) with a maximum carotenoid yield of 13.37 mg/l culture fluid on the 4.5th day. The chemical composition of the carotenoid-protein preparation has been identified. The respective carotenoid and protein content is 497.4 microg/g dry cells and 50.3% per dry weight, respectively. An important characteristic of the carotenoid composition is the high percentage (51.1%) of beta-carotene (a carotenoid pigment with the highest provitamin A activity) as compared to 12.9% and 33.7%, respectively, for the other two individual pigments--torulene and torularhodin. Exopolysaccharides (12.8 g/l) synthesized by the yeast and lactic acid cultures, identified as acid biopolymers containing 7.2% glucuronic acid, were isolated in the cell-free supernatant. Mannose, produced exclusively by the yeast, predominated in the neutral carbohydrate biopolymer component (76%). The mixed cultivation of R. rubra GED8 with the yogurt starter (L. bulgaricus 2-11 + S. thermophilus 15HA) in ultrafiltrate under conditions of intracellular production of maximum amount of carotenoids and exopolysaccharides synthesis enables combined utilization of the culture fluid from the fermentation process.
authors.affiliation: Laboratory of Applied Microbiology, Institute of Microbiology, Bulgarian Academy of Sciences, 4002 Plovdiv, 26 Maritza Blvd., Bulgaria. vafrengov@abv.bg
authors.forename: Ginka I
authors.initials: GI
authors.lastname: Frengova
authors.forename: Emilina D
authors.initials: ED
authors.lastname: Simova
authors.forename: Dora M
authors.initials: DM
authors.lastname: Beshkova
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D002338:Carotenoids / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism*; D007700:Kinetics; D007778:Lactobacillus / Q000254:growth & development; D011134:Polysaccharides / Q000096:biosynthesis*; D012248:Rhodotorula / Q000254:growth & development* / Q000378:metabolism*; D048249:Streptococcus thermophilus / Q000254:growth & development; D015014:Yogurt / Q000382:microbiology*; D019207:beta Carotene / Q000096:biosynthesis*
chemical_list: D000596:Amino Acids; D005656:Fungal Proteins; D011134:Polysaccharides; D019207:beta Carotene; D002338:Carotenoids