Combined cross-linked enzyme aggregates (combi-CLEAs) for efficient integration of a ketoreductase and a cofactor regeneration system

•Combi-CLEAs had been demonstrated to be a robust regeneration system for cofactor.•Negligible amount of cofactor successfully started high speed regeneration.•Possible homogeneous and adjacent dispersion of two enzymes may lead to quick uptake of cofactor. An alternative strategy for cofactor regeneration in the synthesis of valuable chiral alcohols catalyzed by ketoreductases was developed. combi-CLEAs of ketoreductase and d-glucose dehydrogenase enabled the repeated and effective conversion of substrate ethyl 4-chloro-3-oxobutanoate (COBE) with several superiorities. Wide application of this strategy in production of various chiral alcohols could be expected in the future for its high efficiency with low cost.