| novel system consisting of a synthetic biofilm has been developed for improving enzyme activity and extending the active life in immobilized whole cell biocatalysts. In this model, Escherichia coli are immobilized by combining the bacteria with an acrylic/vinyl acetate copolymer and casting this solution into 5 to 100 micron thick biofilms. High cell loadings facilitate increased productivity per unit volume, and multi-layer films are designed to ensure that the entrapped cells will not leave the matrix. Methods have been developed to determine total protein content and enzyme activity in immobilized cells, as well as to investigate diffusion properties of the films. In addition, laser scanning confocal microscopy and fluorescent staining have been employed to show that E. coli viability remains high (greater than 90%) for at least two weeks and cell distribution is uniform throughout multi-layer films. These tools have been used in single and sequential induction experiments using wild-type lacZ for comparing immobilized and planktonic cells. Also, translational fusions of... |
