Yeast cells immobilized in spherical gellan particles cross-linked with magnesium acetate

In this paper we report on the production of microbioreactors using ionically cross-linked gellan containing immobilized yeast cells with potential application in glucose fermentation. Cross-linking was achieved through a novel extrusion process in capillary by ionotropic gelation under the action of magnesium acetate. Compared to commonly used methods, this provides a host of practical advantages. The particles were physico-chemically and morphologically characterized as their mechanical stability, behavior in aqueous media, and bio-catalytic activity are influenced by the amount of cross-linker used. This demonstrated their ability to be reused in a large number of fermentation cycles without losing their bio-catalytic activity. Our results are wholly comparable with the behavior of free yeast. We show that fermentation cycles can succeed either immediately or at variable intervals, ensuring high yields of glucose transformation, comparable-if not superior-to results currently obtained using free yeast.