Encapsulation of specific Salmonella   Enteritidis phage f3αSE on alginate-spheres as a method for protection and dosification

Background: Bacteriophages have been proposed as an alternative to control pathogenic bacteria resistant to antibiotics. However, they are not extensively used due to different factors such as vulnerability under environmental conditions and the lack of efficient administration methods. A potential solution is the encapsulation of bacteriophages in hydrogel polymers to increase their viability and as a controlled release method. This work describes the use of alginate-Ca⁺² matrixes as mechanisms for protection and dosification of the phage f3αSE which has been successfully used to prevent infections produced by Salmonella Enteritidis.
Results: The viability of the pure phage is reduced in near 100% after 1-h incubation at pH 2 or 3. However, the encapsulated phage remains active in 80, 6% at pH 3, while no differences were observed at pH 2, 4 or 7. Exposition of f3αSE to different T° showed that the viability of this phage decreased with increased T° to near 15% at 60°C, while the encapsulated phage remains with 50% viability at same temperature. Finally, the encapsulation of phages showed to extend their presence for 100 h in the medium compared to non-encapsulated phages in a water flow system, which simulate automatic birdbath used in poultry industry, maintaining the phage concentration between 10² and 10⁴ PFU/mL during 250 h.
Conclusions: Encapsulation in alginate-Ca⁺² spheres can be a good alternative to extend viability of phages and can be used as a phage method dosification method in water flow systems.

Keywords
Alginate encapsulation; Alginate; Bacteriophage encapsulation; Bacteriophage therapy; Bacteriophage; Flow; Hydrogel polymers; Phage protection; Phage survival; Phages; Sphere