title: Production of the Marine Carotenoid Astaxanthin by Metabolically Engineered Corynebacterium glutamicum.
abstract: Astaxanthin, a red C40 carotenoid, is one of the most abundant marine carotenoids. It is currently used as a food and feed additive in a hundred-ton scale and is furthermore an attractive component for pharmaceutical and cosmetic applications with antioxidant activities. Corynebacterium glutamicum, which naturally synthesizes the yellow C50 carotenoid decaprenoxanthin, is an industrially relevant microorganism used in the million-ton amino acid production. In this work, engineering of a genome-reduced C. glutamicum with optimized precursor supply for astaxanthin production is described. This involved expression of heterologous genes encoding for lycopene cyclase CrtY, β-carotene ketolase CrtW, and hydroxylase CrtZ. For balanced expression of crtW and crtZ their translation initiation rates were varied in a systematic approach using different ribosome binding sites, spacing, and translational start codons. Furthermore, β-carotene ketolases and hydroxylases from different marine bacteria were tested with regard to efficient astaxanthin production in C. glutamicum. In shaking flasks, the C. glutamicum strains developed here overproduced astaxanthin with volumetric productivities up to 0.4 mg·L(-1)·h(-1) which are competitive with current algae-based production. Since C. glutamicum can grow to high cell densities of up to 100 g cell dry weight (CDW)·L(-1), the recombinant strains developed here are a starting point for astaxanthin production by C. glutamicum.
authors.affiliation: Genetics of Prokaryotes, Faculty of Biology &amp; CeBiTec, Bielefeld University, Bielefeld D-33615, Germany. n.henke@uni-bielefeld.de.
authors.forename: Nadja A
authors.initials: NA
authors.lastname: Henke
authors.affiliation: Genetics of Prokaryotes, Faculty of Biology &amp; CeBiTec, Bielefeld University, Bielefeld D-33615, Germany. saeheider@aol.com.
authors.forename: Sabine A E
authors.initials: SA
authors.lastname: Heider
authors.affiliation: Genetics of Prokaryotes, Faculty of Biology &amp; CeBiTec, Bielefeld University, Bielefeld D-33615, Germany. petra.peters-wendisch@uni-bielefeld.de.
authors.forename: Petra
authors.initials: P
authors.lastname: Peters-Wendisch
authors.affiliation: Genetics of Prokaryotes, Faculty of Biology &amp; CeBiTec, Bielefeld University, Bielefeld D-33615, Germany. volker.wendisch@uni-bielefeld.de.
authors.forename: Volker F
authors.initials: VF
authors.lastname: Wendisch
mesh_terms: D002338:Carotenoids / Q000378:metabolism*; D048230:Corynebacterium glutamicum / Q000378:metabolism*; D060847:Metabolic Engineering / Q000379:methods; D006899:Mixed Function Oxygenases / Q000378:metabolism; D010105:Oxygenases / Q000378:metabolism; D024341:Xanthophylls / Q000378:metabolism; D019207:beta Carotene / Q000378:metabolism
chemical_list: D024341:Xanthophylls; D019207:beta Carotene; C011431:decaprenoxanthin; D002338:Carotenoids; C005948:astaxanthine; D006899:Mixed Function Oxygenases; D010105:Oxygenases; C093259:beta-carotene ketolase
keywords: astaxanthin production; carotenoids; genome-reduced Corynebacterium glutamicum; metabolic engineering; systematic approach