New reaction procedures for selective C-H-oxyfunctionalizations are important for the development of sustainalbe processes in chemical and pharmaceutical industries. Cytochrome P450 (CYP) monooxygenases catalyze such reactions, but the productivity of biotransformations with recombinant microorganisms harboring CYPs is often too low to meet industrial requirements. This thesis focuses on the optimization of CYP-based processes by improving parameters that affect microbial physiology.