Diversity, astaxanthin production, and genomic analysis of Rhodotorula paludigena SP9-15

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 115 isolates, 11 were identified that produced astaxanthin. Molecular identification techniques revealed these isolates belonged to two species: Rhodotorula paludigena (5 isolates) Rhodosporidiobolus ruineniae (6 isolates). Whole-genome analysis one representative strain, R. SP9-15, putative candidate synthesis-associated genes, such as CrtE, CrtYB, CrtI, CrtS, CrtR, CrtW, CrtO, CrtZ. High-performance liquid chromatography (HPLC) chromatography-mass spectrometry (LC-MS) confirmed production. Further optimization production was carried out by investigating the effects various factors growth rate The optimal conditions 40 g/L glucose carbon source, pH 7.5, cultivation at 25 °C with 200 rpm 3 days. Under conditions, SP9-15 synthesized biomass 11.771 ± 0.003 g/L, resulting content 0.558 0.018 mg/g DCW (dry cell weight), an yield 6.565 0.238 mg/L, productivity 2.188 0.069 g/L/day. These findings provide insights into using red Thailand highlight potential further application.