[Immobilization of E. coli cells in polyacrylamide-based microporous cryogels]

E. coli cells were immobilized in polyacrylamide cryogel by three ways: (1) introduction of cells in the reaction mixture followed by cryopolymerization; (2) the filling of the cryogel pores followed by cell fixation with diluted glutaric dialdehyde (GDA), and (3) the filling of the macropores of the polymeric matrix with modified surface. The ultrastructure of the gels and immobilized cells as well as distribution of attachment of the cells immobilized by different techniques were studied. The first type of immobilization was characterized by the highest quantity of the biomass in the gel (by protein) and by a sharp decrease of the cell viability. The second failed to retain the cells in the pores, and the GDA treatment significantly decreased the viability index. The latter technique was the mildest and completely maintained the viability of the population. However, the biomass content was lower as compared to the first type of immobilization, but could be considerably increased by the GDA treatment.