ABSTRACT
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.
Subject(s)
Acrylic Resins , Escherichia coli , Gels , Bacteriological Techniques , Escherichia coli/ultrastructure , Microscopy, ElectronABSTRACT
The ultrastructural organization of the cell wall surface was studied in the fungus Aspergillus terreus 17P growing on different substrates: glucose, a sodium salt of carboxymethyl cellulose (CMC) which is a soluble derivative of cellulose, ground straw. Cells grown on soluble substrates (glucose and Na-CMC) had a smooth surface in the logarithmic growth phase. Cells grown on straw, a solid insoluble substrate, released a substance of a polysaccharide nature which formed a thick fibrillar network on the surface. The electron-microscopic cytochemistry showed a relationship between cellulases and exocellular polysaccharides.
