Biocoatings: A new challenge for environmental biotechnology

•Biocoatings increase 500-1000 fold the immobilized biomass.•Biocoatings preserve and extend the shelf life of cells.•Biocoatings allow making artificial biofilms for wastewater treatments.•Biocoatings elicit the design of artificial consortia for hard biodegradations.

Adhesive biocatalytic coatings (biocoatings) have a nanoporous microstructure generated by partially coalesced waterborne polymer particles that entrap highly concentrated living cells in a dry state stabilized by carbohydrate osmo-protectants. Biocoatings can be deposited by high speed coating technologies, aerosol delivery or ink-jet printed in multilayered, patterned coatings on flexible nonporous or nonwoven substrates, preserving 1010-1012 non-growing viable microorganisms per m2 in 2-50 μm thick layers. Cells are rehydrated to restore their metabolism. The layers reactive half-life following rehydration can be 1000 s of hours. The planar structure of biocoatings enable uniform illumination of a high concentration of photo-reactive microorganisms or algae and contact these microbe with thin liquid films for efficient mass transfer. This review highlights recent advances in biocoating technology for pollutants degradation, photo-reactive coatings, stabilization of hyperthermophiles for biocatalysis, environmental biosensors, and biocomposite fuel cells. Engineering cells for desiccation tolerance, unveiling the metabolism of non-growing cells, and engineering the interaction between the cell surface and adhesive polymer binders are fundamental challenges to open the door to vast future applications of biocoatings for environmental sensing and remediation.

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