Application of chitosan-alginate microspheres for the sustained release of bacteriophage in simulated gastrointestinal conditions

This study was designed to evaluate the acid stability, release property and antimicrobial efficacy of Escherichia coli O157:H7 bacteriophages encapsulated in chitosan-alginate microspheres under the simulated gastrointestinal conditions. The bacteriophages belonging to Myoviridae family were stable at the pH above 4 in trypticase soy broth. The chitosan-alginate microspheres exhibited protective effect on the viability of bacteriophages in the simulated gastric conditions at pH 2.0 and pH 2.5, showing 4.8 and 5.6 log PFUmL(-1), respectively, after 1h of incubation at 37 degrees C. The release per cent of bacteriophages from microspheres gradually increased up to 65% in the simulated intestinal condition (pH 7.5) at 37 degrees C for 6h. The lytic efficacy of chitosan- and alginate-encapsulated bacteriophages against E.coli O157:H7 was significantly maintained in the simulated intestinal conditions to 10h of incubation (1.3 log reduction). The results suggest that the chitosan-alginate microspheres can be used as a reliable delivery system for bacteriophages.