A computational approach for the simulation and prediction of a linear three-step enzymatic cascade for the synthesis of ϵ-caprolactone (ECL) coupling an alcohol dehydrogenase (ADH), a cyclohexanone monooxygenase (CHMO), and a lipase for the subsequent hydrolysis of ECL to 6-hydroxyhexanoic acid (6-HHA). A kinetic model was developed with an accuracy of prediction for a fed-batch mode of 37% for substrate cyclohexanol (CHL), 90% for ECL, and >99% for the final product 6-HHA. Due to a severe inhibition of the CHMO by CHL, a batch synthesis was shown to be less efficient than a fed-batch approach. In the fed-batch synthesis, full conversion of 100 mM CHL was 28% faster with an analytical yield of 98% compared to 49% in case of the batch synthesis. The lipase-catalyzed hydrolysis of ECL to 6-HHA circumvents the inhibition of the CHMO by ECL enabling a 24% higher product concentration of 6-HHA compared to ECL in case of the fed-batch synthesis without lipase. Biotechnol. Bioeng. 2017;114: 1215–1221.@en

Unspecific peroxygenases have recently gained significant interest due to their ability to catalyse the hydroxylation of non-activated C−H bonds using only hydrogen peroxide as a co-substrate. However, the development of preparative processes has so far mostly concentrated on benzylic hydroxylations using liquid substrates. Herein, we demonstrate the application of a peroxygenase for the hydroxylation of the inert, gaseous substrate butane to 2-butanol in a bubble column reactor. The influence of hydrogen peroxide feed rate and enzyme loading on product formation, overoxidation to butanone and catalytic efficiency is investigated at 200 mL scale. The process is scaled up to 2 L and coupled with continuous extraction. This setup allowed the production of 115 mmol 2-butanol and 70 mmol butanone with an overall total turnover number (TTN) of over 15.000, thereby demonstrating the applicability of peroxygenases for preparative hydroxylation of such inert, gaseous substrates at mild reaction conditions.@en

Enzyme catalysis, made tremendous progress over the last years in identification of new enzymes and new enzymatic reactivity’s as well as optimization of existing enzymes. However, the performance of the resulting processes is often still limited, e.g., in regard of productivity, realized product concentrations and the stability of the enzymes. Different topics (like limited specific activity, unfavourable kinetics or limited enzyme stability) can be addressed via enzyme engineering. On the other hand, there is also a long list of topics that are not addressable by enzyme engineering. Here typical examples are unfavourable reaction thermodynamics, selectivity in multistep reactions or low water solubility. These challenges can only be addressed through an adaption of the reaction system. The procedures of process intensification (PI) represent a good approach to reach most suitable systems. The general objective of PI is to achieve significant benefits in terms of capital and operating costs as well as product quality, waste, and process safety by applying innovative principles. The aim of the review is to show the current capabilities and future potentials of PI in enzyme catalysis focused on enzymes of the class of oxidoreductases. The focus of the paper is on alternative methods of energy input, innovative reactor concepts and reaction media with improved properties.@en