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Induced high-yield production of zeaxanthin, lutein, and #-carotene by a mutant of Chlorella zofingiensis Weiping Huang, Yan Lin, Mingxia He, Yuhao Gong, and Junchao Huang J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jafc.7b05400 • Publication Date (Web): 10 Jan 2018 Downloaded from http://pubs.acs.org on January 10, 2018
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Journal of Agricultural and Food Chemistry is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
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Journal of Agricultural and Food Chemistry
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Induced high-yield production of zeaxanthin, lutein, and β-carotene by a
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mutant of Chlorella zofingiensis
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Weiping Huang, Yan Lin, Mingxia He, Yuhao Gong, Junchao Huang*
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Department of Economic Plants and Biotechnology, Yunnan Key Laboratory for Wild Plant
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Resources, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201
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*corresponding author, E-mail address:
[email protected] 11
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Journal of Agricultural and Food Chemistry
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ABSTRACT
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Natural resources of zeaxanthin are extremely limited. A Chlorella zofingiensis mutant (CZ-
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bkt1), which could accumulate high amounts of zeaxanthin, was generated and characterized.
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CZ-bkt1 was achieved by treating the algal cells with a chemical mutagen followed by a
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colour-based colony screening approach. CZ-bkt1 was found to consist of a dysfunctional
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carotenoid ketolase, leading to the accumulation of zeaxanthin rather than its downstream
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ketocarotenoid astaxanthin. Light irradiation, glucose, NaCl, and nitrogen deficiency all
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induced CZ-bkt1 to accumulate zeaxanthin. CZ-bkt1 accumulated zeaxanthin up to
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7.00±0.82 mg/g when induced by high light irradiation and nitrogen deficiency, and
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36.79±2.23 mg/L by additional feeding with glucose. Furthermore, in addition to zeaxanthin,
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CZ-bkt1 also accumulated high amounts of β-carotene (7.18±0.72 mg/g or 34.64±1.39 mg/L)
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and lutein (13.81±1.23 mg/g or 33.97±2.61 mg/L). CZ-bkt1 is the sole species up to date with
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the ability to accumulate high amounts of the three carotenoids that are essential for human
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health.
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KEYWORDS
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Carotenoid; Chlorella zofingiensis; Zeaxanthin; Lutein; Microalgae
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Journal of Agricultural and Food Chemistry
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1. INTRODUCTION
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Carotenoids are yellow to red pigments synthesized by all photosynthetic organisms. Lutein,
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β-carotene, and zeaxanthin are three typical carotenoids with important biological functions.
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They are essential nutrients for human health in that β-carotene serves as provitamin A, while
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lutein and zeaxanthin are important pigments in the retina 1, 2. Vitamin A deficiency is a
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public health problem in developing countries, which has prompted great efforts toward the
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biofortification of plant-derived foods with provitamin A carotenoids 3, 4. High dietary intake
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of zeaxanthin and lutein proved to decrease the risk of age-related macular degeneration, the
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main cause of blindness of elder people 5. Zeaxanthin and lutein have been used as feed
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additives and colorants in the food industry for animals 6, 7. Studies have also found that
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zeaxanthin could reduce the risks of cataract, cancer and low-density lipoprotein oxidation 8, 9.
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At least 2 mg/day of zeaxanthin was recommended by European Commission for adult health
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10, 11
.
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Microalgae have been exploited for producing high-value carotenoids, e.g. astaxanthin
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from Haematococcus pluvialis 12, β-carotene from Dunaliella bardawill 13 and lutein from
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Chlorella species 14. Compared with other carotenoids, zeaxanthin levels are extremely low,
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e.g.,
