Reconstructing Candida glycerinogenes Metabolism to Efficiently Synthesize (-)-α-Bisabolol

(-)-α-Bisabolol is one of the important derivatives in the mevalonate (MVA) pathway. Yeast not only possesses a complete MVA metabolic pathway but also has mature modification and optimization strategies, among which transcription factor regulation is a very effective method. In this study, by screening transcription factors associated with the MVA pathway, a new regulatory factor, ECM22, was discovered that can be used for terpenoid synthesis, and ECM22 proved to be the most effective compared to other screened transcription factors. Previous studies have indicated that ECM22 is related to sterol synthesis, as it enters the nucleus through its N-terminal domain to recognize and bind to sterol regulatory elements (SREs) on promoters, thereby activating the transcriptional activity of target genes. Based on the characteristics of this transcription factor, we achieved fine-tuning of (-)-α-bisabolol synthesis by optimizing sterol elements and varying sterol content, resulting in a 280% diversion of carbon flux toward (-)-α-bisabolol synthesis. This is the first time ECM22 has been utilized in the terpenoid synthesis process, allocating the largest metabolic flux to the synthesis pathway of terpenoids. Ultimately, we obtained 1442.22 mg/L of (-)-α-bisabolol through fed-batch fermentation in a 5 L bioreactor, advancing the precise directional regulation of terpenoid metabolic engineering.