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    Item type:Publication,
    Optimization of astaxanthin production by Rhodotorula toruloides CB6-10/1 using response surface methodology and its genome analysis
    (2026-02-01)
    Butsararattanagomen, Pornthipa
    ;
    Tanasupawat, Somboon
    ;
    Kingkaew, Engkarat
    ;
    Kotatha, Ditpon
    ;
    Soontorngun, Nitnipa
    Astaxanthin is a valuable carotenoid with potent antioxidant properties and has broad applications in the pharmaceutical, nutraceutical, and cosmetic industries. In this study, Rhodotorula toruloides CB6-10/1, isolated from Canna indica L. flowers, was evaluated for astaxanthin production. The orange-red pigment was confirmed as astaxanthin via thin-layer chromatography and high-performance liquid chromatography, with quantification performed by spectrophotometry. Comprehensive genome analysis and production optimization of R. toruloides CB6-10/1 confirmed the presence of key astaxanthin biosynthesis genes, such as CrtYB, CrtI, CrtW, CrtZ, and CrtR, which facilitate the conversion of β-carotene to astaxanthin through hydroxylation and ketolation. The key parameters, including carbon and nitrogen sources, their concentrations, trace elements, agitation speed, and pH, were systematically evaluated to optimize production. Although copper appeared beneficial in the Plackett–Burman screening, its effect and those of other metals were not significant. Optimization using Response Surface Methodology for cost-effective nitrogen sources determined that a combination of 1.10 g/L yeast extract, 10.0 g/L peptone, and 0.50 g/L ammonium sulfate yielded the maximum astaxanthin production of 4.728 mg/L, under cultivation conditions of pH 4.5, 200 rpm, and 30 g/L glucose, representing a fourfold increase compared with the basal medium. This optimization not only enhances pigment production efficiency but also reduces dependency on costly trace elements, improving process scalability and economic feasibility. Overall, these results demonstrate R. toruloides CB6-10/1 as a promising microbial source for sustainable astaxanthin production with potential further applications.
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    Item type:Publication,
    Enhancement of astaxanthin production in novel red yeast Rhodosporidiobolus sp. SP3-3/4 and genomic characterization
    (2025-10-01)
    Phuengjayaem, Sukanya
    ;
    Kingkaew, Engkarat
    ;
    Hoondee, Patcharaporn
    ;
    Tanasupawat, Somboon
    Astaxanthin is a red carotenoid and potent antioxidant with anti-inflammatory, anti-cancer, neuroprotective, and immuno-enhancing benefits. This study focused on enhancing astaxanthin production using a novel red yeast, strain SP3-3/4, through genomic analysis. Strain SP3-3/4 shared 99.66% sequence identity in the D1/D2 domain of the large subunit rRNA gene with Rhodosporidiobolus ruineniae CBS 5001<sup>T</sup>. Whole-genome analysis indicated 82.54% similarity to R. ruineniae JCM 8097<sup>T</sup>, with average nucleotide identity (ANI) values below 80% for other strains. The ANI result, lower than the 95% cutoff, confirms SP3-3/4 as a novel species, Rhodosporidiobolus sp. SP3-3/4. Key astaxanthin synthesis genes, including CrtE, CrtYB, CrtI, CrtS, CrtR, CrtW, CrtO, and CrtZ, were annotated. Astaxanthin production was verified using HPLC and LC-MS. Optimization of medium composition and physical parameters identified optimal conditions as 20 g/L sucrose, 3 g/L yeast extract, and 5 g/L peptone, with an initial medium pH of 6.5. Maximum cell growth and astaxanthin content, reaching 9.615 g/L and 0.46 mg/g DCW, respectively, were achieved after 5 days of cultivation, corresponding to an astaxanthin yield of 6.93 mg/L and a productivity rate of 1.39 mg/L/day. Notably, a maximum productivity of 1.45 mg/L/day occurred in 3 days. These findings elucidated comprehensive optimization of astaxanthin production, incorporating functional genomic assessment and analysis of protein-encoded genes of astaxanthin-producing yeast Rhodosporidiobolus sp. SP3-3/4. Such insights represent valuable biological resources with significant implications for diverse biotechnological and bioinformatics applications.
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    Item type:Publication,
    Astaxanthin producing yeasts: Production and genomic analysis
    (2024-09-16)
    Kingkaew, Engkarat
    ;
    Phuengjayaem, Sukanya
    ;
    Tanasupawat, Somboon
    This chapter explores yeasts and their potential in carotenoid production, delving into the diverse roles of carotenoids, their biosynthesis, and applications. Carotenoids, found in various organisms, serve several crucial functions, including light harvesting, photoprotection, and antioxidant activity. The focus shifts to astaxanthin, a red-orange carotenoid with immense market value and applications, notably in aquaculture and health. The astaxanthin-producing yeast strains emerge as a promising biotechnological platform for carotenoid production, particularly astaxanthin. Its unique features, FDA approval, and ability to synthesize carotenoids make it an ideal candidate for industrial applications. This chapter details the structure of astaxanthin and its biosynthetic pathway, emphasizing key genes involved. Additionally, it highlights other carotenoid producers and the biochemistry of astaxanthin. The latter part focuses on the health-promoting effects of astaxanthin, including antioxidant, anti-inflammatory, anti-diabetic, and anticancer activities. Immunomodulation benefits and the safety profile of astaxanthin are also discussed. The chapter concludes by addressing current trends, perspectives, and challenges in astaxanthin production, emphasizing the importance of circular, zero-waste processes.
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    Item type:Publication,
    Diversity, astaxanthin production, and genomic analysis of Rhodotorula paludigena SP9-15
    (2023-07-01)
    Phuengjayaem, Sukanya
    ;
    Kingkaew, Engkarat
    ;
    Hoondee, Patcharaporn
    ;
    Rojsitthisak, Pornchai
    ;
    Sritularak, Boonchoo
    Astaxanthin is a carotenoid known for its powerful antioxidant properties. This study focused on isolating yeast strains capable of producing astaxanthin from flower and fruit samples collected in Thailand. Out of 115 isolates, 11 strains were identified that produced astaxanthin. Molecular identification techniques revealed that these isolates belonged to two species: Rhodotorula paludigena (5 isolates) and Rhodosporidiobolus ruineniae (6 isolates). Whole-genome analysis of one representative strain, R. paludigena SP9-15, identified putative candidate astaxanthin synthesis-associated genes, such as CrtE, CrtYB, CrtI, CrtS, CrtR, CrtW, CrtO, and CrtZ. High-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS) confirmed astaxanthin production. Further optimization of astaxanthin production was carried out by investigating the effects of various factors on the growth rate and astaxanthin production. The optimal conditions were 40 g/L glucose as a carbon source, pH 7.5, and cultivation at 25 °C with 200 rpm for 3 days. Under these conditions, R. paludigena SP9-15 synthesized biomass of 11.771 ± 0.003 g/L, resulting in astaxanthin with a content of 0.558 ± 0.018 mg/g DCW (dry cell weight), an astaxanthin yield of 6.565 ± 0.238 mg/L, and astaxanthin productivity of 2.188 ± 0.069 g/L/day. These findings provide insights into astaxanthin production using red yeast strains from Thailand and highlight the potential of R. paludigena SP9-15 for further application.