Protective action of antioxidants on Escherichia coli cells immobilized in polyacrylamide gel

The object of this work was to find out whether antioxidants could be used for weakening the effect of free radicals on Escherichia coli cells immobilized in polyacrylamide gel. Some of the antioxidants soluble in lipids and water (ionol, Epigid, glutathione) protected the cells against the action of free radicals produced in the process of acrylamide polymerization, and increased the viability of the immobilized bacteria.     

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.     

Escherichia coli membrane-bound polyphosphatase]

A complex of polyphosphatase with E. coli membranes has been isolated and studied. It is shown by gel-filtration through G-200 Sephadex and centrifugation in sucrose concentration gradient that about 5% of polyphosphatase total content in cells is bound with the heterogenous fraction containing smooth membranes and the ribosome-membrane complex. On the basis of the data obtained it is suggested that the formation of a complex of polyphosphatase with membranes is a stage of synthesis and secretion of this enzyme to protoplasm.     

Degradation of alkylsulfates by a Pseudomonas aeruginosa culture immobilized on a polyvinyl alcohol fiber

Pseudomonas aeruginosa cells capable of destroying alkyl sulfates, anionic surfactants, were immobilised on activated polyvinyl alcohol fibres. The immobilised cells could decompose SDS. When the immobilised cells were used repeatedly, their biomass increased but the activity hardly changed.