Abstract
Astaxanthin is one of the strongest natural antioxidants and a red pigment occurring in nature. This C40 carotenoid is used in a broad range of applications such as a colorant in the feed industry, an antioxidant in cosmetics or as a supplement in human nutrition. Natural astaxanthin is on the rise and, hence, alternative production systems are needed. The natural carotenoid producer Corynebacterium glutamicum is a potent host for industrial fermentations, such as million-ton scale amino acid production. In C. glutamicum, astaxanthin production was established through heterologous overproduction of the cytosolic lycopene cyclase CrtY and the membrane-bound β-carotene hydroxylase and ketolase, CrtZ and CrtW, in previous studies. In this work, further metabolic engineering strategies revealed that the potential of this GRAS organism for astaxanthin production is not fully exploited yet. It was shown that the construction of a fusion protein comprising the membrane-bound β-carotene hydroxylase and ketolase (CrtZ~W) significantly increased astaxanthin production under high glucose concentration. An evaluation of used carbon sources indicated that a combination of glucose and acetate facilitated astaxanthin production. Moreover, additional overproduction of cytosolic carotenogenic enzymes increased the production of this high value compound. Taken together, a seven-fold improvement of astaxanthin production was achieved with 3.1 mg/g CDW of astaxanthin.
Highlights
The demand for naturally produced astaxanthin is estimated to witness an exponential growth of 25% (CAGR) by 2025 [1]
C. glutamicum isstrains limitedisby the conversion of β-carotene to astaxanthin and/or the overall towardsflux carotenoid limited by the conversion of β-carotene to astaxanthin and/or flux the overall towards products
Astaxanthin production in C. glutamicum was improved through the application of of three different strategies, namely: construction of membrane fusion-proteins, overproduction of three different strategies, namely: construction of membrane fusion-proteins, overproduction of cytosolic carotenoid biosynthesis enzymes and use of blends of glucose and potassium acetate as cytosolic carotenoid biosynthesis enzymes and use of blends of glucose and potassium acetate as fermentation substrates
Summary
The demand for naturally produced astaxanthin is estimated to witness an exponential growth of 25% (CAGR) by 2025 [1]. This fact is in accordance with a worldwide trend: consumers seek for natural products that are produced in an environmentally friendly way. The feed industry, which is the main purchaser of astaxanthin, is growing as well in order to satisfy the demand for animal-based food products such as meat, fish and eggs [2]. Fermentations with Corynebacterium glutamicum dominate food and feed biotechnology since decades for the production of amino acids e.g. l-glutamate and l-lysine [3,4,5].
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
