title: Construction of the astaxanthin biosynthetic pathway in a methanotrophic bacterium Methylomonas sp. strain 16a.
abstract: Methylomonas sp. strain 16a is an obligate methanotrophic bacterium that uses methane or methanol as the sole carbon source. An effort was made to engineer this organism for astaxanthin production. Upon expressing the canthaxanthin gene cluster under the control of the native hps promoter in the chromosome, canthaxanthin was produced as the main carotenoid. Further conversion to astaxanthin was carried out by expressing different combinations of crtW and crtZ genes encoding the beta-carotenoid ketolase and hydroxylase. The carotenoid intermediate profile was influenced by the copy number of these two genes under the control of the hps promoter. Expression of two copies of crtZ and one copy of crtW led to the accumulation of a large amount of the mono-ketolated product adonixanthin. On the other hand, expression of two copies of crtW and one copy of crtZ resulted in the presence of non-hydroxylated carotenoid canthaxanthin and the mono-hydroxylated adonirubin. Production of astaxanthin as the predominant carotenoid was obtained in a strain containing two complete sets of carotenoid biosynthetic genes. This strain had an astaxanthin titer ranging from 1 to 2.4 mg g(-1) of dry cell biomass depending on the growth conditions. More than 90% of the total carotenoid was astaxanthin, of which the majority was in the form of E-isomer. This result indicates that it is possible to produce astaxanthin with desirable properties in methanotrophs through genetic engineering.
authors.affiliation: DuPont Central Research and Development, E328/148B Experimental Station, Route 141, Henry Clay Rd., Wilmington, DE 19880, USA. rick.ye@usa.dupont.com
authors.forename: Rick W
authors.initials: RW
authors.lastname: Ye
authors.forename: Henry
authors.initials: H
authors.lastname: Yao
authors.forename: Kristen
authors.initials: K
authors.lastname: Stead
authors.forename: Tao
authors.initials: T
authors.lastname: Wang
authors.forename: Luan
authors.initials: L
authors.lastname: Tao
authors.forename: Qiong
authors.initials: Q
authors.lastname: Cheng
authors.forename: Pamela L
authors.initials: PL
authors.lastname: Sharpe
authors.forename: Wonchul
authors.initials: W
authors.lastname: Suh
authors.forename: Eva
authors.initials: E
authors.lastname: Nagel
authors.forename: Dennis
authors.initials: D
authors.lastname: Arcilla
authors.forename: Dominic
authors.initials: D
authors.lastname: Dragotta
authors.forename: Edward S
authors.initials: ES
authors.lastname: Miller
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D053898:Biosynthetic Pathways; D016644:Canthaxanthin / Q000737:chemistry / Q000378:metabolism; D002338:Carotenoids / Q000737:chemistry / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D005285:Fermentation; D008697:Methane / Q000378:metabolism; D020620:Methylomonas / Q000235:genetics* / Q000378:metabolism*; D008954:Models, Biological; D015394:Molecular Structure; D024341:Xanthophylls / Q000096:biosynthesis / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D024341:Xanthophylls; D002338:Carotenoids; D016644:Canthaxanthin; C005948:astaxanthine; D008697:Methane