Characterization of cyanobacterial [beta]-carotene ketolase and hydroxylase genes in Escherichia coli, and their application for astaxanthin biosynthesis

• Published in: Biotechnology and bioengineering Vol. 103; no. 5; p. 944
• Main Authors: Scaife, Mark A, Burja, Adam M, Wright, Phillip C
• Format: Journal Article
• Language: English
• Published: New York Wiley Subscription Services, Inc 01.08.2009
• Subjects: Bacteria; E coli; Enzymes; Gene expression; Genes; Protein synthesis; Vitamin A
• ISSN: 0006-3592; 1097-0290

Carotenoid biosynthesis is highly conserved and well characterized up to the synthesis of β- carotene. Conversely, the synthesis of astaxanthin from β-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 -carotene ketolase and 4 β-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 β-carotene ketolase and β-carotene hydroxylase genes, within a β-carotene accumulating host, enables a 23.5-fold improvement in total carotenoid yield (1.99 mg g...), over the parental strain, with >90% astaxanthin. (ProQuest: ... denotes formulae/symbols omitted.)