Microencapsulation of phages to analyze their demeanor in physiological conditions.

Nowadays, phage therapy emerges as one of the alternative solutions to the problems arising from antibiotic resistance in pathogenic bacteria. Although phage therapy has been successfully applied both in vitro and in vivo, one of the biggest concerns in this regard is the stability of phages in body environment. Within the scope of this study, microencapsulation technology was used to increase the resistance of phages to physiological conditions, and the resulting microcapsules were tested in environments simulating body conditions. For this purpose, Bacillus subtilis, Salmonella enterica subsp. enterica serovar Enteritidis (Salmonella Enteritidis), and Salmonella enterica subsp. enterica serovar Typhimurium (Salmonella Typhimurium) phages were isolated from different sources and then microencapsulated with 1.33% (w/v) sodium alginate using a spray dryer to minimize the damage of physiological environment. Stability of microcapsules in simulated gastric fluid and bile salt presence was tested. As a consequence, the maximum titer decrease of microencapsulated phages after 2-h incubation was found to be 2.29 log unit for B. subtilis phages, 1.71 log unit for S. Enteritidis phages, and 0.60 log unit for S. Typhimurium phages, while free phages lost their viability even after a 15-min incubation. Similarly, microencapsulation was found to increase the stability of phages in the bile salt medium and it was seen that after 3 h of incubation, the difference between the titers of microencapsulated phages and free phages could reach up to 3 log unit.