Carrier systems for bacteriophages to supplement food systems: Encapsulation and controlled release to modulate the human gut microbiota

• Methods to encapsulate Lactococcus lactis phage P008 were tested and optimized.
• Sensitivity of encapsulated phage and free phage to acid conditions was analyzed.
• Release of phage from the capsules by exposure to intestinal fluid was determined.
• The encapsulation improved the survival of phage under acidic conditions at pH 2.
• Phage release up to 90% after incubation in intestinal fluid was observed.

The use of phages in food systems to modulate the human gut microbiota is currently gaining increasing interest. However, several studies have reported low viability of phages under gastrointestinal conditions. Furthermore, processed foods nowadays contain only few phage particles. Hence, this study aimed at encapsulating phages to increase their survival under gastrointestinal conditions allowing the release of phages in active form in the intestine.Lactococcus phage P008 was entrapped in different matrix materials, using three different encapsulation techniques (i.e., emulsion or extrusion method). Results showed that non-encapsulated phages were sensitive to acid conditions at pH 2.0. However, the investigated capsules which contained milk proteins provided good protection of phages at pH 2.0: a phage reduction of only 0.5 log-units was observed after incubation for 120 min at 37 °C. The release of phages from capsules after 2 h incubation in simulated intestinal fluid (pH 6.8) was also determined. Depending on the encapsulation technique, phages were completely released from the capsules. Micrographs confirmed these observations and showed a dissolution of the capsule matrix due to swelling and permeation of pancreatic enzyme. The study indicates that encapsulated phages may be targeted via food formulation to the intestine to modulate the human gut microbiota.