Affiliations 

  • 1 Colin Ratledge Center for Microbial Lipids, School of Agricultural Engineering and Food Science, Shandong University of Technology, Zibo, China
  • 2 Departamento de Genética y Microbiología (Unidad asociada al Instituto de Química Física Rocasolano-Consejo Superior de Investigaciones Científicas (IQFR-CSIC)), Facultad de Biología, Universidad de Murcia, Murcia, Spain
Front Nutr, 2021;8:756218.
PMID: 34722614 DOI: 10.3389/fnut.2021.756218

Abstract

Canthaxanthin is a reddish-orange xanthophyll with strong antioxidant activity and higher bioavailability than carotenes, primarily used in food, cosmetics, aquaculture, and pharmaceutical industries. The spiking market for natural canthaxanthin promoted researchers toward genetic engineering of heterologous hosts for canthaxanthin production. Mucor circinelloides is a dimorphic fungus that produces β-carotene as the major carotenoid and is considered as a model organism for carotenogenic studies. In this study, canthaxanthin-producing M. circinelloides strain was developed by integrating the codon-optimized β-carotene ketolase gene (bkt) of the Haematococcus pluvialis into the genome of the fungus under the control of strong promoter zrt1. First, a basic plasmid was constructed to disrupt crgA gene, a negative regulator of carotene biosynthesis resulted in substantial β-carotene production, which served as the building block for canthaxanthin by further enzymatic reaction of the ketolase enzyme. The genetically engineered strain produced a significant amount (576 ± 28 μg/g) of canthaxanthin, which is the highest amount reported in Mucor to date. Moreover, the cell dry weight of the recombinant strain was also determined, producing up to more than 9.0 g/L, after 96 h. The mRNA expression level of bkt in the overexpressing strain was analyzed by RT-qPCR, which increased by 5.3-, 4.1-, and 3-folds at 24, 48, and 72 h, respectively, compared with the control strain. The canthaxanthin-producing M. circinelloides strain obtained in this study provided a basis for further improving the biotechnological production of canthaxanthin and suggested a useful approach for the construction of more valuable carotenoids, such as astaxanthin.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.