Characterization of cyanobacterial beta-carotene ketolase and hydroxylase genes in Escherichia coli, and their application for astaxanthin biosynthesis.
Carotenoid biosynthesis is highly conserved and well characterized up to the synthesis of beta-carotene. Conversely, the synthesis of astaxanthin from beta-carotene is less well characterized. Regardless, astaxanthin is a highly sought natural product, due to its various industrial applications and elevated antioxidant capacity. In this article, 12 beta-carotene ketolase and 4 beta-carotene hydroxylase genes, isolated from 5 cyanobacterial species, are investigated for their function, and potential for microbial astaxanthin synthesis. Further, this in vivo comparison identifies and applies the most promising genetic elements within a dual expression vector, which is maintained in Escherichia coli. Here, combined overexpression of individual beta-carotene ketolase and beta-carotene hydroxylase genes, within a beta-carotene accumulating host, enables a 23.5-fold improvement in total carotenoid yield (1.99 mg g(-1)), over the parental strain, with >90% astaxanthin.
Biological and Environmental Systems Group, ChELSI, Department of Chemical and Process Engineering, University of Sheffield, Mappin Street, Sheffield S13JD, United Kingdom.
Mark A
MA
Scaife
Adam M
AM
Burja
Phillip C
PC
Wright
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D053898:Biosynthetic Pathways / Q000235:genetics; D000458:Cyanobacteria / Q000201:enzymology*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism*; D010105:Oxygenases / Q000235:genetics / Q000378:metabolism*; D024341:Xanthophylls / Q000096:biosynthesis; D019207:beta Carotene / Q000378:metabolism
D001426:Bacterial Proteins; D024341:Xanthophylls; D019207:beta Carotene; C005948:astaxanthine; D006899:Mixed Function Oxygenases; D010105:Oxygenases; C093259:beta-carotene ketolase; C079232:beta-carotene hydroxylase