Synthesis of carotenoids by Rhodotorula rubra GED8 co-cultured with yogurt starter cultures in whey ultrafiltrate.
Two cultures, a yeast ( Rhodorula rubra GED8) and a yogurt starter ( Lactobacillus bulgaricus 2-11+ Streptococcus thermophilus 15HA), were selected for associated growth in whey ultrafiltrate (WU) and active synthesis of carotenoids. In associated cultivation with the yogurt culture L bulgaricus 2-11+S. thermophilus 15HA under intensive aeration (1.3 l(-1)min(-1) air-flow rate) in WU (45 g lactose l(-1)), initial pH 5.5, 30 degrees C, the lactose-negative strain R. rubra GED8 synthesized large amounts of carotenoids (13.09 mg l(-1 )culture fluid). The carotenoid yield was approximately two-fold higher in association with a mixed yogurt culture than in association with pure yogurt bacteria. The major carotenoid pigments comprising the total carotenoids were beta-carotene (50%), torulene (12.3%) and torularhodin (35.2%). Carotenoids with a high beta-carotene content were produced by the microbial association 36 h earlier than by Rhodotorula yeast species. No significant differences were notd in the ratio between the pigments synthesized by R. rubra GED8+ L. bulgaricus 2-11, R. rubra GED8+ S. thermophilus 15HA, and R.rubra GED8+yogurt culture, despite the fact that the total carotenoid concentrations were lower in the mixed cultures with pure yogurt bacteria.
Laboratory of Applied Microbiology, Bulgarian Academy of Sciences, 26 Maritza Blvd., Institute of Microbiology, 4002 Plovdiv, Bulgaria. lbpmbas@plov.omega.bg
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Simova
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Frengova
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Beshkova
D002338:Carotenoids / Q000096:biosynthesis*; D018920:Coculture Techniques; D003470:Culture Media; D007700:Kinetics; D019344:Lactic Acid / Q000378:metabolism*; D008894:Milk Proteins / Q000378:metabolism*; D012248:Rhodotorula / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D000067816:Whey Proteins; D015014:Yogurt
D003470:Culture Media; D008894:Milk Proteins; D000067816:Whey Proteins; D019344:Lactic Acid; D002338:Carotenoids