Metabolic mechanism of astaxanthin biosynthesis in Xanthophyllomyces dendrorhous in response to sodium citrate treatment

Abstract Astaxanthin is an important ketocarotenoid widely used in industries. However, its application limited because of low yield. Sodium citrate (Na-citrate), one the major carbon sources for microorganisms, can promote cell growth and product accumulation. The basidiomycetous red yeast Xanthophyllomyces dendrorhous was thus to study effect Na-citrate on astaxanthin synthesis. highest biomass yield (6.0 g/L 22.5 mg/L) were obtained shake-flask when 3 added at 24 h 1.8 2.0 times higher than those control group, respectively. Furthermore, metabolomics real-time reverse transcription PCR (qRT-PCR) analysis conducted metabolic pathways X. response Na-citrate. qRT-PCR assay revealed that facilitated glucose consumption, promoted flux from glycolysis, regulated tricarboxylic acid (TCA) cycle, providing more energy substrates synthesis astaxanthin. gene adding significantly upregulated expression six key genes ( ICL , HMGS crtE crtYB crtI, crtS ) involved related biosynthesis. These results suggest exogenous treatment a potentially valuable strategy stimulate production .