The ratio of substrate to catalyst (S/C) is a prime target for the application of asymmetric production of enantiomerically enriched intermediates by whole-cell biocatalyst. In the present study, an attractive increase in S/C was achieved in a natural deep-eutectic solvent (NADES) containing reaction system under microaerobic condition for high production of (S)-1-[3,5-bis(trifluoromethyl)phenyl]ethanol ((S)-3,5-BTPE) with Candida tropicalis 104. In PBS buffer (0.2 M, pH 8.0) at 200 rpm and 30 °C, 79.5 g (Dry Cell Weight, DCW)/L C. tropicalis 104 maintained the same yield of 73.7% for the bioreduction of 3,5-bis(trifluoromethyl)acetophenone (BTAP) under an oxygen-deficient environment compared with oxygen-sufficient conditions, while substrate load increased 4.0-fold (from 50 mM to 200 mM). Furthermore, when choline chloride:trehalose (ChCl:T, 1:1 molar ratio) was introduced into the reaction system for its versatility of increasing cell membrane permeability and declining BTAP cytotoxicity to biocatalyst, the yields were further increased to 86.2% under 200 mM BTAP, or 72.9% at 300 mM BTAP. After the optimization of various reaction parameters involved in the bioreduction, and the amount of biocatalyst and maltose co-substrate remained 79.5 g (DCW)/L and 50 g/L, the S/C for the reduction elevated 6.3 times (3.8 mM/g versus 0.6 mM/g). By altering the respiratory pattern of the whole-cell biocatalyst and exploiting the ChCl:T-containing reaction system, the developed strategy exhibits an attractive potential for enhancing catalytic efficiency of whole-cell-mediated reduction, and provides valuable insight for the development of whole-cell catalysis.

中文翻译：

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在含深共晶溶剂的微需氧介质系统中通过全细胞催化剂高效生产 (S)-1-[3,5-双(三氟甲基)苯基]乙醇

底物与催化剂的比率 (S/C) 是应用全细胞生物催化剂不对称生产富含对映异构体的中间体的主要目标。在本研究中，在微需氧条件下，在含有天然深共晶溶剂 (NADES) 的反应体系中实现了 S/C 的显着增加，以高产 (S)-1-[3,5-双(三氟甲基)苯基]乙醇 ((S)-3,5-BTPE) 和热带念珠菌 104。在 200 rpm 和 30 °C 的 PBS 缓冲液（0.2 M，pH 8.0）中，79.5 g（干细胞重量，DCW）/L C.tropicalis与氧充足条件相比，104 在缺氧环境下生物还原 3,5-双（三氟甲基）苯乙酮 (BTAP) 的产率保持不变，为 73.7%，而底物负载增加了 4.0 倍（从 50 mM 到 200毫米）。此外，当氯化胆碱:海藻糖 (ChCl:T, 1: 1 摩尔比）被引入反应系统，因为它具有增加细胞膜通透性和降低 BTAP 对生物催化剂的细胞毒性的多功能性，在 200 mM BTAP 下产率进一步提高到 86.2%，在 300 mM BTAP 下产率为 72.9%。生物还原中涉及的各种反应参数优化后，生物催化剂和麦芽糖共底物的量保持在79.5 g (DCW)/L和50 g/L，还原的S/C提高了6.3倍(3.8 mM/L) g 与 0.6 mM/g）。通过改变全细胞生物催化剂的呼吸模式并利用含 ChCl:T 的反应系统，所开发的策略在提高全细胞介导的还原催化效率方面表现出极具吸引力的潜力，并为全细胞生物催化剂的发展提供了宝贵的见解。 -细胞催化。