Jiawei Tang

Enfumafungin, a triterpenoid antifungal compound, serves as the key starting material for the synthesis of ibrexafungerp and SCY-247. However, its low fermentation yield and high production cost constrain its supply, limiting drug accessibility and the ability to meet clinical demand. Consequently, enhancing enfumafungin biosynthesis is crucial for achieving large-scale production. In this study, physical and chemical mutagenesis treatments were adopted for Hormonema carpetanum ATCC 74360, and a genetically stable high-producing mutant, H. carpetanum ENF-5-29, was generated. This mutant produced 817 mg/L enfumafungin in flasks, a 30-fold increase over that of wild-type ATCC 74360. Comparative transcriptome analysis revealed that the proposed biosynthetic pathway from glucose to enfumafungin presented the most significant upregulation in the mutant. The fermentation medium and conditions were subsequently optimized to further enhance enfumafungin production. Transcriptome analysis revealed improved yields under low-temperature culture, likely due to the upregulated expression of key genes in the mevalonate pathway and the enfumafungin biosynthetic gene cluster (BGC). Together, these transcriptome findings provide molecular insight into enhanced enfumafungin production. Furthermore, batch fermentation of ENF-5-29 in a 5 L bioreactor achieved a yield of 1,621 mg/L, the highest yield reported to date. Our results demonstrate the efficacy of mutagenesis for H. carpetanum improvement and pinpoint key targets for future genetic engineering aimed at enhancing enfumafungin biosynthesis. Graphical abstract

A chemoenzymatic synthesis of the veterinary antibiotic florfenicol is described. The key step involves the dynamic reductive kinetic resolution (DYRKR) of a keto ester by using a ketoreductase‐02 (KRED‐02) to afford the two contiguous stereocenters of the (2S,3R)‐cis‐1,2‐amino alcohol intermediate in >99 % ee and a diastereomeric ratio (dr) of 99 %. This green biocatalysis is environmental friendly with high enantioselectivity and product yields. Two methods for the nucleophilic fluorination step involved the use of aziridines and cyclic sulfates to safely prepare fluoroamines with high regioselectivity. Additional studies have indicated that KRED‐02 can also be used to afford chiral alcohol (S)‐21 in good yields with high enantioselectivity. This study shows that the integration of biocatalysis into organic synthesis can be useful and provide industrial opportunities for applications of florfenicol.