Unexpected distribution of immobilized microorganisms within alginate beads.

Immobilization refers to the prevention of free cell movement by natural or artificial means. It has always been assumed that immediately after an immobilization procedure is performed, cells are distributed homogeneously in the beads that entrap them. However, in this study, Escherichia coli and Trichoderma asperellum distribution in alginate-gel beads was found to be nonhomogeneous. In fact, there was a greater presence of cells on the surface of the alginate beads than in their cores.