Microencapsulation with alginate/CaCO3: A strategy for improved phage therapy

Abstract

Bacteriophages are promising therapeutic agents that can be applied to different stages of the commercial food chain. In this sense, bacteriophages can be orally administered to farm animals to protect them against intestinal pathogens. However, the low pH of the stomach, the activities of bile and intestinal tract enzymes limit the efficacy of the phages. This study demonstrates the utility of an alginate/CaCO3 encapsulation method suitable for bacteriophages with different morphologies and to yield encapsulation efficacies of ~100%. For the first time, a cocktail of three alginate/CaCO3-encapsulated bacteriophages was administered as oral therapy to commercial broilers infected with Salmonella under farm-like conditions. Encapsulation protects the bacteriophages against their destruction by the gastric juice. Phage release from capsules incubated in simulated intestinal fluid was also demonstrated, whereas encapsulation ensured sufficient intestinal retention of the phages. Moreover, the small size of the capsules (125–150 μm) enables their use in oral therapy and other applications in phage therapy. This study evidenced that a cocktail of the three alginate/CaCO3-encapsulated bacteriophages had a greater and more durable efficacy than a cocktail of the corresponding non-encapsulated phages in as therapy in broilers against Salmonella, one of the most common foodborne pathogen.

Microencapsulation of Clostridium difficile specific bacteriophages using microfluidic glass capillary devices for colon delivery using pH triggered release

“…A number of previous studies have used alginate as the main encapsulating agent either on its own [37], [63], [64] or in combination with whey protein [32], [60], [61] or chitosan [31], [33]. Phages encapsulated in crosslinked pure alginate microparticles were found to be susceptible to acid damage following exposure to simulated gastric fluid [31], [37], [62].…”

“…The porosity of the alginate gel microparticles affects phage susceptibility to acid damage due to diffusion of acid. A number of studies have added CaCO 3 within the microparticles to protect phage from acid damage [37], [63]. Other studies have shown that by combining alginate with chitosan [31], [80] or whey protein [32], [60], [61], better acid protection may be achieved.…”

“…Previous studies on phage encapsulated in large microparticles (~ 1mm) have reported slower sustained release kinetics for alginate encapsulated phage [31], [33]. Colom et al [63] reported faster release from small alginate microparticles containing CaCO 3 as antacid (mean size ~ 100 μm). However, exposure to simulated gastric fluid (pH 2.8 for 60 min) resulted in between 2 log and 3 log reduction in Salmonella phage titre suggesting that even with the addition of CaCO 3 , phage were highly susceptible to SGF.…”

“…Smaller particles may be predisposed to non-specific mucoadhesion [92], [93] which may aid in phage retention and sustained release over a signficant time period. Colom et al [63] showed better phage retention (for animals treated with encapsulated phage versus those treated with free phage) in the caecum of chickens and a significant reduction in Salmonella colonisation, attributing these results to the mucoadhesiveness of the small alginate microparticles (~ 100 μm) used for encapsulating phage. Wittaya-areekul et al, [94] showed differences in mucoadhesion properties of chitosan coated alginate microparticles using an in vitro assay using porcine gut tissue samples.…”

Bakteriyofajların Antibakteriyel Ajan Olarak Kullanımı

“…Kontrol grubu enfekte tavuklar ile serbest ve mikrokapsüle bakteriyofaj karışımı verilen enfekte tavukların kör bağırsaklarında 15 günün sonunda S. typhimurium ATCC14028 Rif R sayısı sırasıyla 5.2±1.3, 6.3±1.0 ve 3.5±2.1 log kob/g olarak tespit edilmiştir. Çalışmanın sonucunda Salmonella ile enfekte olan ticari broiler tavuklarda ağız yoluyla faj terapisinin başarıyla uygulandığı değerlendirilmiştir [32].…”