Biocatalytic Coatings: Investigation of Gene Expression in Whole-Cell Biocatalysis on Surfaces, Within Composite Latex Membranes, or in Latex Microstructures

One of our main focus areas is the study of whole-cell biocatalysis on surfaces. Over the past ten years our group had developed multi layer acrylate/vinyl acetate latex coating technology to produce composite biocatalytic coatings containing a high volume fraction of living bacteria. Latex biocatalytic coatings may change the way microorganisms are stored, transported, and used on surfaces as biosensors, in bioelectronic devices, or in membranes and composite microstructures.

Biocatalytic coatings are fundamentally different from natural biofilms in that biocatalytic coatings are thin, they have a porous polymer sealant top layer, which permanently entraps the cells, and the embedded microorganisms must survive the physical forces which occur during film formation as well as partial desiccation during coat drying. Both drawdown coating and piezoelectric (ink jet) printing methods are used to generate 10μm to 100μm thick composite latex patches, three dimensional microstructures, or coated filaments containing bacteria. Coating composition is optimized to generate porosity and so that the embedded microorganisms survive film formation and partial desiccation during controlled coat drying.

Spatial gene expression in the coatings is studied with Professor Schottel's laboratory using E. coli containing mercury II inducible indicator constructs such as mer-lux or mer-gfp. Laser scanning confocal microscopy (LSCM) is used to determine cell viability and kinetics of gene expression. Coating microstructure, polymer particle coalescence, and coating permeability are investigated in diffusion cells. With Professor Scriven’s group we study coating microstructure using fast freeze cryogenic scanning electron microscopy (cryo-SEM).

Polymer blend coatings stable at elevated temperatures (in excess of 80EC) that may be useful for high temperature biocatalysis are studied using Thermotoga maritima as the model anaerobic halotolerant biocatalyst. Latex biocatalyic coatings for industrial oxidations or reductions are being studied using Gluconobacter oxydans and other microbial systems. Biocatalytic coatings may also be useful as biosensors, in automated gene expression screening, and as components of bioelectronic devices by coating onto integrated circuits containing sensors capable of detecting changes in gene expression.

Current collaborators on this project include: J.L. Schottel (BMBB), L.E. "Skip" Scriven (CEMS), J.D. Stewart, University of Florida, Gainesville, G. Saylor, University of Tennessee, M. Simpson, ORNL).