Biotransformations with engineered E. coli cells expressing wild-type and mutant Baeyer–Villiger monooxygenases under non-growing conditions

The Escherichia coli (E. coli) overexpression systems of Baeyer–Villiger monooxygenases (BVMOs), cyclohexanone monooxygenase (CHMO) and cyclopentanone monooxygenase (CPMO) and their mutants derived from directed evolution were used as catalysts in oxidations of six 4-substituted cyclohexanones. The biotransformations were carried out with growing cells (standard screening conditions) and with non-growing cells. The surprising result is that several substrates that give negative results (non-acceptance) under the screening conditions, afford excellent conversions in the transformations under non-growing conditions. The new bioreagents for Baeyer–Villiger oxidations with divergent, high enantioselectivities reported here can be used in scaled-up fermentation under non-growing conditions.