Efficacy of Different Encapsulation Techniques on the Viability and Stability of Diverse Phage under Simulated Gastric Conditions.

causes a range of diseases in humans and livestock of considerable public health and economic importance. Widespread antimicrobial use, particularly in intensively produced livestock (e.g., poultry and pigs) may contribute to the rise of multidrug-resistant strains. Alternative treatments such as bacteriophages have shown promise when used to reduce the intestinal carriage of in livestock. However, the digestive enzymes and low pH encountered in the monogastric GI tract can significantly reduce phage viability and impact therapeutic outcomes. This study deployed alginate-carrageenan microcapsules with and without CaCO to protect a genomically diverse set of five bacteriophages from simulated gastrointestinal conditions. None of the unprotected phage could be recovered following exposure to pH < 3 for 10 min. Alginate-carrageenan encapsulation improved phage viability at pH 2-2.5 after exposure for 10 min, but not at pH 2 after 1 h. Including 1% (/) CaCO in the formulation further reduced phage loss to <0.5 log PFU/mL, even after 1 h at pH 2. In all cases, phage were efficiently released from the microcapsules following a shift to a neutral pH (7.5), simulating passage to the duodenum. In summary, alginate-carrageenan-CaCO encapsulation is a promising approach for targeted intestinal delivery of genomically diverse bacteriophages.