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Scaife M.A.,Ocean Nutrition Canada Ltd. | Scaife M.A.,University of Cambridge | Prince C.A.,Ocean Nutrition Canada Ltd. | Prince C.A.,Molecular Microbiology Group | And 2 more authors.
Process Biochemistry | Year: 2012

Canthaxanthin has significant commercial value due to its use as an antioxidant and feed additive in aquaculture and poultry farms. The biological production of high-value carotenoids, such as canthaxanthin, represents a significant challenge. Presented here is an Escherichia coli bioprocess, which includes the recombinant production of a strain, a novel medium and a fermentation process, for the efficient biosynthesis of canthaxanthin. The chromosomal overexpression of the E. coli genes Idi, Dxs and Dxr increased the carbon flux into the plasmid-based canthaxanthin biosynthetic pathway, achieving a total carotenoid productivity of 11.7 mg/g (91% canthaxanthin). The development of a novel culture medium increased the productivity 2.9-fold to 78.2 mg/L total carotenoids. This high-titer platform was subsequently employed for the analysis of mutations known to be advantageous to carotenoid biosynthesis, providing the first such evaluation in a high titer background. This demonstrated that thee increased expression of IspB or the deletion of PykF, PykA or YtjC improved the total carotenoid yield, whereas the increased expression of Pps and Ppc, was not improve productivity. This analysis resulted in an increase in the carotenoid yield to 16.1 mg/g. The use of 1 L lab-scale fermentations allowed for further improvements in productivity, and 170 mg/L total carotenoids was obtained. © 2012 Elsevier Ltd. Source


Scaife M.A.,Ocean Nutrition Canada Ltd. | Scaife M.A.,University of Cambridge | Ma C.A.,Ocean Nutrition Canada Ltd. | Ma C.A.,Molecular Microbiology Group | And 4 more authors.
Journal of Natural Products | Year: 2012

Astaxanthin (3,3'-dihydroxy-4,4'-diketo-β-carotene) (1) is a carotenoid of significant commercial value due to its superior antioxidant potential, application as a component of animal feeds, and ongoing research that links its application to the treatment and prevention of human pathologies. The high commercial cost of 1 is also based upon its complex synthesis. Chemical synthesis has been demonstrated, but produces a mixture of stereoisomers with limited applications. Production from biological sources is limited to natural producers with complex culture requirements. The biosynthetic pathway for 1 is well studied; however, questions remain that prevent optimized production in heterologous systems. Presented is a direct comparison of 12 β-carotene (2) hydroxylases derived from archaea, bacteria, cyanobacteria, and plants. Expression in Escherichia coli enables a comparison of catalytic activity with respect to zeaxanthin (3) and 1 biosynthesis. The most suitable β-carotene hydroxylases were subsequently expressed from an efficient dual expression vector, enabling 1 biosynthesis at levels up to 84% of total carotenoids. This supports efficient 1 biosynthesis by balanced expression of β-carotene ketolase and β-carotene hydroxylase genes. Moreover, our work suggests that the most efficient route for astaxanthin biosynthesis proceeds by hydroxylation of β-carotene to zeaxanthin, followed by ketolation. © 2012 American Chemical Society and American Society of Pharmacognosy. Source


Scaife M.A.,Nutrition Canada Ltd. | Scaife M.A.,University of Cambridge | Ma C.A.,Nutrition Canada Ltd. | Ma C.A.,Molecular Microbiology Group | Armenta R.E.,Nutrition Canada Ltd.
Bioresource Technology | Year: 2012

Canthaxanthin has a substantial commercial market in aquaculture, poultry production, and cosmetic and nutraceutical industries. Commercial production is dominated by chemical synthesis; however, changing consumer demands fuel research into the development of biotechnology processes. Highly productive microbial systems to produce carotenoids can be limited by the efficiency of extraction methods. Extraction with hexane, acetone, methanol, 2-propanol, ethanol, 1-butanol, tetrahydrofuran and ethyl acetate was carried out with each solvent separately, and subsequently the most efficient solvents were tested in combination, both as mixtures and sequentially. Sequential application of methanol followed by acetone proved most efficient. Extraction efficiency remained stable over a solvent to biomass range of 100:1 to 55:1, but declined significantly at a ratio of 25:1. Application of this method to a canthaxanthin-producing Escherichia coli production system enabled efficient canthaxanthin extraction of up to 8.5mgg -1 dry biomass. © 2012 Elsevier Ltd. Source


Grant
Agency: Narcis | Branch: Project | Program: Completed | Phase: Physics, Chemistry and Medicine | Award Amount: | Year: 2007

Most of the therapeutic proteins (e.g. antibodies and hormones) are proteins that are secreted by human cells via the secretory pathway. Many of these therapeutic proteins are glycosylated during passage through this pathway and the glycans on the protein often play a crucial role in their pharmacological properties. At the moment, therapeutic proteins are produced in mammal cell lines. Construction of these lines is complex and culturing expensive. Mushroom forming basidiomycetes are interesting candidates for the efficient production of therapeutic glycoproteins. They have a glycosylation pattern which is more similar to that of humans than that of plants and other fungi. Within this project we will improve heterologous protein production in mushroom and will further humanize its glycosylation machinery.


Reed D.L.,University of Florida | Currier R.W.,American Veterinary Medical History Society | Walton S.F.,University of The Sunshine Coast | Conrad M.,New York University | And 21 more authors.
Annals of the New York Academy of Sciences | Year: 2011

The following series of concise summaries addresses the evolution of infectious agents in relation to sex in animals and humans from the perspective of three specific questions: (1) what have we learned about the likely origin and phylogeny, up to the establishment of the infectious agent in the genital econiche, including the relative frequency of its sexual transmission; (2) what further research is needed to provide additional knowledge on some of these evolutionary aspects; and (3) what evolutionary considerations might aid in providing novel approaches to the more practical clinical and public health issues facing us currently and in the future? © 2011 New York Academy of Sciences. Source

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