The Delta 5,7‐Sterols and Astaxanthin in the Marine Microheterotroph Schizochytrium sp. S31

Abstract

The thraustochytrids, the heterotrophic marine microorganisms, have received increasing attention because of their capacity for the production of high‐value products such as docosahexaenoic acid (DHA), carotenoids, and sterols. In this study, three potential Δ5,7‐sterols, showing similar UV absorption spectra to that of ergosterol, in the thraustochytrid Schizochytrium sp. S31, were estimated by the ultraperformance liquid chromatography (UPLC) − APCI−MS/MS method. The proposed structures of three Δ5,7‐sterols were ergosta‐5,7,24(28)‐trien‐3β‐ol, ergosta‐5,7‐dien‐3β‐ol, and 24‐ethylcholesta‐5,7,22‐trien‐3β‐ol. The contents of astaxanthin, ergosterol, and the other three Δ5,7‐sterols in Schizochytrium sp. S31 during the cultivation performed in three separate batches were analyzed by a fast UPLC–PDA method. The results demonstrated that astaxanthin, ergosterol, and ergosta‐5,7‐dien‐3β‐ol were the predominant carotenoid and Δ5,7‐sterols, respectively, and their contents kept increasing during the growth and reached a maximum after 23 days of cultivation. The estimated maximum contents of astaxanthin and four Δ5,7‐sterols, including ergosterol, ergosta‐5,7‐dien‐3β‐ol, ergosta‐5,7,24(28)‐trien‐3β‐ol, and 24‐ethylcholesta‐5,7,22‐trien‐3β‐ol were 2.31, 4.02, 3.43, 0.30, and 0.97 mg g−1 dry biomass, respectively. These findings are different to other strains reported in the composition and accumulation of Δ5,7‐sterols and carotenoids. The present study suggests that Schizochytrium sp. S31 might be a promising marine microorganism for the productions of high‐value natural pigment astaxanthin, the provitamin D2 ergosterol, and the provitamin D4 ergosta‐5,7‐dien‐3β‐ol, and taken as a model organism to study the sterologenesis of the microorganisms because of its complexity of sterol compositions.

Elucidation of sterol biosynthesis pathway and its co-regulation with fatty acid biosynthesis in the oleaginous marine protist Schizochytrium sp.

“…However, ergosterol has been detected in Schizochytrium sp. S31 using ultraperformance liquid chromatography method in a previous study ( Jiang et al, 2020 ). We speculated that the failure of ergosterol detection in this study might be due to technical limitations and different culture conditions.…”

“…HX-308 ( Ren et al, 2015 ), Schizochytrium limacinum B4D1 ( Zhu et al, 2022 ), Schizochytrium sp. S31 ( Jiang et al, 2020 ), Schizochytrium mangrovei PQ6 ( Hang et al, 2019 ), and Schizochytrium sp. MYA1381 ( Li et al, 2019 ).…”

“…The major sterols include cholesterol, stigmasterol, ergosterol, lanosterol, and cycloartenol. Despite the efforts to chemically describe the sterol content of numerous Schizochytrium species, the biochemistry of the Schizochytrium sterol biosynthesis pathway remains unclear ( Ren et al, 2015 ; Du et al, 2019 ; Jiang et al, 2020 ). The diversity of the sterol species of Schizochytrium also rendered the determination of the pathway in the tripartite subdivision difficult.…”

The Biosynthesis of Astaxanthin Esters in Schizochytrium sp. is Mediated by a Bifunctional Diacylglycerol Acyltransferase

“…has received significant attention due to its high levels of DHA, an omega-3 long-chain polyunsaturated fatty acid (PUFA) that contributes to brain and eye development, as well as the maintenance of a balanced inflammatory response . A few strains belonging to Schizochytrium, Thraustochytrium, and Aurantiochytrium, also produce carotenoids and squalene in addition to DHA. Carotenoids, particularly astaxanthin, have strong antioxidation, anti-inflammatory, and anticancer effects, making them useful in the food, feed, and pharmaceutical industries.…”