Scanning Microfluorimetry of Ca-Alginate Immobilized Zymomonas Mobilis

Abstract

Scanning microfluorimetric techniques offer a means for in situ investigation of spatial heterogeneities in biomass density and cell composition in macroscopic, aggregate-cell systems such as immobilized-cell biocatalysts, biofilms, mold pellets and tumors. Much of the analytical power of flow cytometry, with the important addition of spatial resolution, can be brought to bear on the study of these systems. The utility of these techniques is demonstrated for the experimental determination of spatial gradients in biomass density and bio-catalytic activity in Ca-alginate beads containing an entrapped, living bacterium, Zymomonas mobilis ATCC 10988. Using cell RNA content as an indicator of cell growth rate, scanning microfluorimetry data indicates that immobilized cells in a single gel bead can exhibit the fullest possible variation in specific growth rates, from maximal to resting. Thus, clear gradients in biological growth rate within such biocatalysts are quantifiable, with implications for any fully or partially growth associated products.