Optimizing encapsulation of Staphylococcus aureus bacteriophage phiIPLA-RODI

Trabajo presentado en el EMBO Workshop: Viruses of Microbes V: Biodiversity and future applications, celebrado en Wroclaw (Polonia), del 9 al 13 de julio de 2018The antimicrobial properties of bacteriophages make them suitable biopreservatives for foods. In this study, we evaluated the encapsulation as a system to delivery bacteriophages and to increase their stability during foodstuffs processing. Staphylococcus aureus bacteriophage phiIPLA-RODI was encapsulated in simple and double emulsions, niosomes, liposomes and transfersomes. Out of them, niosomes, liposomes and transfersomes were found to be efficient systems to encapsulate phage phiIPLA-RODI. Niosomes and liposomes formulated with 30 and 50 mg/ml of surfactants showed percentages of encapsulation of 94-100%, while 50 or 70 mg/ml of surfactants were necessary to obtain similar results with transfersomes. Size distribution of emulsions ranged from 0.98 µm to 29 µm, while size of niosomes, liposomes and transfersomes were 0.82 ± 0.09 µm, 1.66 ± 0.21 µm and 0.55 ± 0.06 µm, respectively. Bacteriophage infectivity was well maintained along the storage time at 4°C for at least 6 months, with the exception of those encapsulated in liposomes with 30 mg/ml of surfactants, which reduced phage titer in 3 log units after four months. Regarding the viability of free and encapsulated phages, niosomes protected phage particles from low pH. Thus, free phiIPLA-RODI was not detectable after 60 min exposure to pH 4.2, while titer of encapsulated phage in niosomes only decreases 2 log units. On the other hand, the treatment of vesicles with 4.5 M NaCl during 60 min resulted in a high instability of the vesicles and the consequent release of the encapsulated phage phiIPLA-RODI. Overall, our results showed that encapsulation represents an appropriate procedure to improve stability and antimicrobial activity of phages even in adverse conditions used in food processing industry.Peer reviewe