Yang Mengyuan, Hao Jing, Zhang Rong, He Ronghai, Ma Haile
School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang, Jiangsu 212013, China.
Institute of Food Physical Processing, Jiangsu University, 301 Xuefu Road, Zhenjiang, Jiangsu 212013, China.
J Agric Food Chem. 2025 Apr 2;73(13):7990-8000. doi: 10.1021/acs.jafc.4c11395. Epub 2025 Mar 19.
Ethyl caproate is the characteristic aroma compound with an apple-like scent in Ginjoka sake. However, the medium-chain acyl-CoA flux of the fatty acid synthesis (FAS) pathway originating from glycolytic fermentation and the precursor-induced alcohol acyltransferase (AAT) activity by natural yeast limits the ethyl caproate content in sake. Here, we established combinatorial strategies involving genetic engineering and adaptive laboratory evolution (ALE) to increase the ethyl caproate production by . In this study, we screened YH-2, which exhibited high ethanol and ester yields , achieving a trade-off between FAS flux and energy metabolism. Subsequently, the cerulenin-resistant mutant strain YH-2-34, after 15 passages of adaptive domestication, produced 4.13 times more caproic acid than the wild type. This increase is attributed to the G1250S variation in the sequences, which mediate acyl-CoA chain length in the FAS pathway, thereby producing more caproyl-CoA as the precursor. While AAT activity increased 2.40 times in the mutant YH-2-34, both and genes, which together encode AAT responsible for esterifying ethyl caproate, played critical roles. Although overexpression affected cell viability and ethyl caproate production, overexpression successfully increased the yield of ethyl caproate during post-fermentation. Finally, the yield of YH-2-34 with overexpression achieved a significant increase from 1.21 to 7.40 mg/L in sake fermentation. By regulating the flux from glycolytic fermentation to the FAS pathway and overexpressing AAT, we constructed a high-yield ethyl-caproate-producing strain. This may bring practical transformations to traditional brewing industries.
己酸乙酯是吟醸酒中具有苹果香味的特征香气化合物。然而,源自糖酵解发酵的脂肪酸合成(FAS)途径的中链酰基辅酶A通量以及天然酵母诱导的前体酒精酰基转移酶(AAT)活性限制了吟醸酒中己酸乙酯的含量。在此,我们建立了涉及基因工程和适应性实验室进化(ALE)的组合策略,以提高己酸乙酯的产量。在本研究中,我们筛选出了YH-2,其表现出高乙醇和酯产量,在FAS通量和能量代谢之间实现了权衡。随后,经过15代适应性驯化后的抗浅蓝菌素突变株YH-2-34产生的己酸比野生型多4.13倍。这种增加归因于FAS途径中调节酰基辅酶A链长度的序列中的G1250S变异,从而产生更多作为前体的己酰辅酶A。虽然突变体YH-2-34中的AAT活性增加了2.40倍,但共同编码负责酯化己酸乙酯的AAT的 和 基因发挥了关键作用。虽然 过表达影响细胞活力和己酸乙酯产量,但 过表达在发酵后阶段成功提高了己酸乙酯的产量。最后,过表达 的YH-2-34在吟醸酒发酵中的产量从1.21毫克/升显著增加到7.40毫克/升。通过调节从糖酵解发酵到FAS途径的通量并过表达AAT,我们构建了高产己酸乙酯生产菌株。这可能会给传统酿造行业带来实际变革。