title: Improvement of carotenoid-synthesizing yeast Rhodotorula rubra by chemical mutagenesis.
abstract: A mutant Rhodotorula rubra with enhanced carotenoid-synthesizing activity for synthesizing total carotenoids and beta-carotene was obtained by N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis. When co-cultivated with yogurt starter bacteria (Lactobacillus bulgaricus + Streptococcus thermophilus) in whey ultrafiltrate it produced 15.7 mg total carotenoids l(-1) culture fluid or 946 microg total carotenoids g(-1) dry cells of which 71% was beta-carotene. Grown as a monoculture in glucose substrate, the mutant shown 1.4 times lower carotenoid-synthesizing activity, and the relative share of beta-carotene in the total carotenoids was lower (63%). The individual pigments torulene and torularhodin were identified, whose mass fractions were (29% and 7%) and (24% and 4%), respectively, for the mutant grown as a monoculture and as a mixed culture with the yogurt bacteria.
authors.affiliation: Laboratory of Applied Microbiology, Institute of Microbiology, Bulgarian Academy of Sciences, 4002 Plovdiv, 26 Maritza Blvd., Bulgaria.
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: D002338:Carotenoids / Q000096:biosynthesis*; D005285:Fermentation; D007700:Kinetics; D008769:Methylnitronitrosoguanidine / Q000494:pharmacology*; D009153:Mutagens / Q000494:pharmacology*; D012248:Rhodotorula / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*
chemical_list: D009153:Mutagens; D008769:Methylnitronitrosoguanidine; D002338:Carotenoids