Ehrlich Pathway Mediated 2-Phenylethanol Production in Candida sorboxylosa: Optimization by Response Surface Methodology and Transcriptomic Validation

2-Phenylethanol (2-PE) is a high-value aromatic alcohol widely applied in food, cosmetic, and fragrance industries due to its characteristic rose-like aroma. In view of the economic and environmental drawbacks of chemical synthesis and plant extraction, this study investigates a sustainable microbial production route using wild-type yeasts. Sugarcane juice was utilized as a natural source for yeast isolation, yielding five distinct strains identified through ITS region sequencing and deposited in the NCBI GenBank database. Among these, Candida sorboxylosa and Yarrowia lipolytica exhibited notable 2-PE production, achieving 420 mg/L and 215.6 mg/L, respectively, in modified YPD medium. Notably, this is the first report of C. sorboxylosa as a 2-PE producer. Process optimization using Response Surface Methodology enhanced 2-PE production to 1.46 g/L under optimized medium conditions. Key optimization variables included dextrose (20 g/L), glycerol (20 g/L), L-phenylalanine (9 g/L), MgSO₄·7H₂O (0.6 g/L), and yeast extract (2 g/L). Transcriptomic analysis showed that specific Ehrlich pathway related genes, including ARO10 and ARO8 were significantly upregulated under L-phenylalanine induction. Several ADH genes exhibited strong upregulation, although not all changes were statistically significant. In contrast, shikimate pathway genes (ARO1, ARO2, and ARO7) showed a non-uniform downregulation trend, indicates pathway redirection toward 2-PE biosynthesis. These findings demonstrated that the optimized culture conditions enable efficient 2-PE production. Overall, this study establishes C. sorboxylosa as a promising non-GMO platform for sustainable 2-PE production.