Cytochrome P450 enzymes (P450s) are heme b containing monooxygenases that introduce one atom of molecular oxygen into a vast range of compounds and catalyze a broad spectrum of reactions, where chemical catalysts often fail. Although the biotechnological potential of these biocatalysts was recognized many years ago, their industrial applications are still rare due to several limitations: The unknown physiological function of most P450s makes the selection of candidate enzymes for a biotechnological process time- and labor intensive. Furthermore, suitable electron transfer proteins are mandatory for efficient P450 biocatalysis. Within this study novel P450s whose oxidizing activities lead to high-value fine chemicals were identified and characterized. A whole cell process with recombinant Escherichia coli was developed to produce the sought-after fragrance (+)-nootkatone. The application of physiological redox proteins thereby greatly reduced uncoupling between NAD(P)H consumption and substrate oxidation by the P450s, which led to improved biocatalytic activities. This book addresses researchers and companies working in the field of biocatalysis and biotechnological research.