Enhancing astaxanthin production in Schizochytrium sp.: Insights from orthogonal experiments and transcriptome analysis

Abstract

Schizochytrium sp. is a marine microorganism used for the commercial production of docosahexaenoic acid (DHA), with applications in the food and feed industries. In addition to DHA, Schizochytrium sp. has the ability to produce trace amounts of carotenoids, including β-carotene and astaxanthin. This study aims to enhance astaxanthin production in Schizochytrium sp. through optimization of culturing conditions. Contrary to previous reports, supplementation with ethanol or isopropanol did not obviously affect astaxanthin production. Notably, reducing nitrogen levels and replacing glucose with fructose led to a 24-fold increase in astaxanthin production (139.3 μg/g dry cell weight) compared to the lipid fermentation conditions. Transcriptomic analysis indicated that upregulation of genes involved in the mevalonate pathway, including acat, crtE, and crtIBY, alongside the β-carotene hydroxylase gene crtZ, probably contributed to the enhanced astaxanthin production. These findings offer a straightforward and efficient approach for improving astaxanthin production in Schizochytrium sp., thereby enhancing its potential applications in the food and feed industries.