Molecular approaches to enhance astaxanthin biosynthesis; future outlook: engineering of transcription factors in Haematococcus pluvialis

Abstract

Microalgae are the preferred species for producing astaxanthin because they pose a low toxicity risk than chemical synthesis. Astaxanthin has multiple health benefits and is being used in: medicines, nutraceuticals, cosmetics, and functional foods. Haematococcus pluvialis is a model microalga for astaxanthin biosynthesis; however, its natural astaxanthin content is low. Therefore, it is necessary to develop methods to improve the biosynthesis of astaxanthin to meet industrial demands, making its commercialization cost-effective. Several strategies related to cultivation conditions are employed to enhance the biosynthesis of astaxanthin in H. pluvialis. However, the mechanism of its regulation by transcription factors is unknown. For the first time, this study critically reviewed the studies on identifying transcription factors, progress in H. pluvialis genetic transformation, and use of phytohormones that increase the gene expression related to astaxanthin biosynthesis. In addition, we propose future approaches, including (i) Cloning and characterization of transcription factors, (ii) Transcriptional engineering through overexpression of positive regulators or downregulation/silencing of negative regulators, (iii) Gene editing for enrichment or deletion of transcription factors binding sites, (iv) Hormonal modulation of transcription factors. This review provides considerable knowledge about the molecular regulation of astaxanthin biosynthesis and the existing research gap. Besides, it provides the basis for transcription factors mediated metabolic engineering of astaxanthin biosynthesis in H. pluvialis.

Keywords:

• Haematococcus pluvialis
• astaxanthin biosynthetic pathway
• transcription factors
• hormones
• transcriptional regulation

Authors contribution

Sadaf-Ilyas Kayani structured and wrote the manuscript. Saeed-ur-Rahman, Qian Shen, Yi Cui, Wei Liu, Xinjuan Hu, Feifei Zhu, Shuhao Huo revised the manuscript. All authors approved the manuscript for submission.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research is supported in part by the National Natural Science Foundation of China [21978120], the Key R&D projects in Jiangsu Province [BE2020405] and Excellent postdoctoral program of Jiangsu province [2022ZB673], and China Postdoctoral Science Foundation [2022M711379].