Characterization of cyanobacterial β-carotene ketolase and hydroxylase genes in Escherichia coli, and their application for astaxanthin biosynthesis
✍ Scribed by Mark A. Scaife; Adam M. Burja; Phillip C. Wright
- Publisher
- John Wiley and Sons
- Year
- 2009
- Tongue
- English
- Weight
- 577 KB
- Volume
- 103
- Category
- Article
- ISSN
- 0006-3592
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✦ Synopsis
Abstract
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 β‐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^−1^), over the parental strain, with >90% astaxanthin. Biotechnol. Bioeng. 2009;103: 944–955. © 2009 Wiley Periodicals, Inc.