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A novel immobilization matrix for the entrapment of viable whole-cell Baeyer–Villiger monooxygenase was developed. Viable recombinant Escherichia coli cells overexpressing cyclohexanone monooxygenase were entrapped in polyelectrolyte complex beads prepared by a two-step reaction of oppositely-charged polymers including highly defined cellulose sulphate. Immobilized cells exhibited higher operational stability than free cells during 10 repeated cycles of Baeyer–Villiger biooxidations of rac-bicyclo[3.2.0]hept-2-en-6-one to the corresponding lactones (1R,5S)-3-oxabicyclo-[3.3.0]oct-6-en-3-one and (1S,5R)-2-oxabicyclo-[3.3.0]oct-6-en-3-one. The morphology of polyelectrolyte complex beads was characterised by environmental scanning electron microscopy; the spatial distribution of polymers in the beads and cell viability were examined using confocal laser scanning microscopy, and the texture was characterised by the mechanical resistance measurements.

A novel immobilization matrix for the entrapment of viable whole-cell Baeyer–Villiger monooxygenase was developed. Viable recombinant Escherichia coli cells overexpressing cyclohexanone monooxygenase were entrapped in polyelectrolyte complex beads prepared by a two-step reaction of oppositely-charged polymers including highly defined cellulose sulphate. Immobilized cells exhibited higher operational stability than free cells during 10 repeated cycles of Baeyer–Villiger biooxidations of rac-bicyclo[3.2.0]hept-2-en-6-one to the corresponding lactones (1R,5S)-3-oxabicyclo-[3.3.0]oct-6-en-3-one and (1S,5R)-2-oxabicyclo-[3.3.0]oct-6-en-3-one. The morphology of polyelectrolyte complex beads was characterised by environmental scanning electron microscopy; the spatial distribution of polymers in the beads and cell viability were examined using confocal laser scanning microscopy, and the texture was characterised by the mechanical resistance measurements.

Proper understanding of viable cell physiology during biocatalytic processes, progress in development of biocompatible immobilization techniques, as well as introduction of new non-invasive characterization techniques are the main prerequisites for the successful development of novel whole-cell biocatalysts. Selection of the optimal immobilized viable cell biocatalyst is possible when standardised characterization techniques are employed. The development of these techniques requires advanced analytics and a multidisciplinary effort. This review provides a summary on progress in development of characterization methods and emerging tools for determination of morphology, physiology, and biocatalytic efficiency of immobilized viable whole cells.

Proper understanding of viable cell physiology during biocatalytic processes, progress in development of biocompatible immobilization techniques, as well as introduction of new non-invasive characterization techniques are the main prerequisites for the successful development of novel whole-cell biocatalysts. Selection of the optimal immobilized viable cell biocatalyst is possible when standardised characterization techniques are employed. The development of these techniques requires advanced analytics and a multidisciplinary effort. This review provides a summary on progress in development of characterization methods and emerging tools for determination of morphology, physiology, and biocatalytic efficiency of immobilized viable whole cells.