Modulation of acetyl-CoA pool and fatty acid metabolism for production of (−)-α-bisabolol in metabolically engineered Yarrowia lipolytica

(−)-α-Bisabolol is a sesquiterpene with a potential of biofuel and also natural compound with anti-inflammatory and skin-whitening properties, commercially produced by solvent extraction from the Brazilian candeia tree and chamomile. This study aimed at engineering an oleaginous yeast of Yarrowia lipolytica for sustainable production of (−)-α-bisabolol from renewable glucose. A codon-optimized MrBBS gene encoding (−)-α-bisabolol synthase from German chamomile was introduced into Y. lipolytica, resulting in the construction of the initial strain (yM) with 22.1 mg/L of (−)-α-bisabolol producing activity. To improve (−)-α-bisabolol production, the mevalonate pathway providing (−)-α-bisabolol precursors was fortified by overexpressing a truncated HMG-CoA reductase and acetyl-CoA thiolase. The intracellular acetyl-CoA pool used as the starting material of (−)-α-bisabolol was expanded by overexpressing ATP-citrate lyase isozymes. The resulting strain of yMtHEA12 produced 681.2 mg/L (−)-α-bisabolol from glucose in batch culture, which was 35.5 times higher than the yM strain. To redirect carbon flux from the native fatty acid biosynthetic pathway which competes with (−)-α-bisabolol synthesis, cerulenin was applied as an inhibitor of fatty acid synthase. Finally, a fed-batch culture of the yMtHEA12 strain through three times addition of glucose and cerulenin supplementation resulted in 1.09 g/L of (−)-α-bisabolol concentration, which was 49.4 times higher than that of the yM strain in the batch culture. Conclusively, Y. lipolytica is a potent microbial workhorse for the sustainable terpene production such as (−)-α-bisabolol, and metabolic engineering strategies optimizing the mevalonate pathway, enhancing the acetyl-CoA pool, and inhibiting fatty acid biosynthesis were effective to enhance (−)-α-bisabolol bioproduction.