Thermotolerant Cyberlindnera jadinii Acquired by Adaptive Laboratory Evolution on Ethanol–Acetate for Improved Single-Cell Protein Production

To obtain thermotolerant Cyberlindnera jadinii strains with high-efficiency utilization of ethanol–acetate carbon sources, serial-batch-transfer adaptive laboratory evolution (ALE) under 37 °C was performed on the wild-type strain C. jadinii TU389, and a thermotolerant evolved strain C. jadinii X131 was acquired. Results demonstrated that C. jadinii X131 exhibited superior biomass accumulation compared to the wild-type strain at both the optimal temperature of 31 °C and 37 °C. Specifically, the X131 strain showed 43.4% higher biomass and 45.1% higher protein yield than wild-type strain at 37 °C in 5 L fermenters, with complete amino acid composition, high amino acid score and relative coefficient. Transcriptomic analysis indicated that temperature ALE reprogrammed ethanol oxidation from the cytoplasm to mitochondria to realize in situ detoxification of acetaldehyde, comprehensively activated DNA replication, chromosome segregation, and chromatin remodeling pathways to sustain cell cycle progression under high temperature, and simultaneously reduced peroxisomal metabolic load and redundant transport pathways. C. jadinii X131 can efficiently utilize ethanol–acetate carbon sources without adaptive trade-offs, which reduces cooling energy consumption in industrial fermentation.