title: Investigation of factors influencing production of the monocyclic carotenoid torulene in metabolically engineered Escherichia coli.
abstract: Factors influencing production of the monocyclic carotenoid torulene in recombinant Escherichia coli were investigated by modulating enzyme expression level, culture conditions, and engineering of the isoprenoid precursor pathway. The gene dosage of in vitro evolved lycopene cyclase crtY2 significantly changed the carotenoid profile. A culture temperature of 28 degrees C showed better production of torulene than 37 degrees C while initial culture pH had no significant effect on torulene production. Glucose-containing LB, 2xYT, TB and MR media significantly repressed the production of torulene, and the other carotenoids lycopene, tetradehydrolycopene, and beta-carotene, in E. coli. In contrast, glycerol-containing LB, 2xYT, TB, and MR media enhanced torulene production. Overexpression of dxs, dxr, idi and/or ispA, individually and combinatorially, enhanced torulene production up to 3.1-3.3 fold. High torulene production was observed in a high dissolved oxygen level bioreactor in TB and MR media containing glycerol. Lycopene was efficiently converted into torulene during aerobic cultures, indicating that the engineered torulene synthesis pathway is well coordinated, and maintains the functionality and integrity of the carotenogenic enzyme complex.
authors.affiliation: Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, 1479 Gortner Avenue, St. Paul 55108, USA.
authors.forename: Pyung Cheon
authors.initials: PC
authors.lastname: Lee
authors.forename: Benjamin N
authors.initials: BN
authors.lastname: Mijts
authors.forename: Claudia
authors.initials: C
authors.lastname: Schmidt-Dannert
mesh_terms: D000332:Aerobiosis; D019747:Aldose-Ketose Isomerases / Q000235:genetics; D019883:Alkyl and Aryl Transferases / Q000235:genetics; D001709:Biotechnology / Q000379:methods; D019748:Carbon-Carbon Double Bond Isomerases / Q000235:genetics; D002338:Carotenoids / Q000031:analogs & derivatives* / Q000032:analysis / Q000096:biosynthesis*; D003470:Culture Media / Q000737:chemistry; D019020:Directed Molecular Evolution; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D018628:Gene Dosage; D015964:Gene Expression Regulation, Bacterial; D051228:Geranyltranstransferase; D005947:Glucose / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D045782:Hemiterpenes; D019753:Intramolecular Lyases / Q000235:genetics; D000077276:Lycopene; D009097:Multienzyme Complexes / Q000235:genetics; D010088:Oxidoreductases / Q000235:genetics; D013696:Temperature; D014166:Transferases / Q000235:genetics; D019207:beta Carotene / Q000032:analysis
chemical_list: D003470:Culture Media; D045782:Hemiterpenes; D009097:Multienzyme Complexes; D019207:beta Carotene; D002338:Carotenoids; C078922:torulene; D010088:Oxidoreductases; C114231:1-deoxy-D-xylulose 5-phosphate reductoisomerase; D014166:Transferases; C109461:deoxyxylulose-5-phosphate synthase; D019883:Alkyl and Aryl Transferases; D051228:Geranyltranstransferase; D019747:Aldose-Ketose Isomerases; D019748:Carbon-Carbon Double Bond Isomerases; C021453:isopentenyldiphosphate delta-isomerase; D019753:Intramolecular Lyases; C070925:lycopene cyclase-isomerase; D005947:Glucose; D005990:Glycerol; D000077276:Lycopene