Bacteriophage cocktail for biocontrol of Escherichia coli O157:H7: Stability and potential allergenicity study

Abstract

Escherichia coli O157:H7 has become a global public health and a food safety problem. Despite the implementation of control strategies that guarantee the safety in various products, outbreaks persist and new alternatives are necessary to reduce this pathogen along the food chain. Recently, our group isolated and characterised lytic bacteriophages against E. coli O157:H7 with potential to be used as biocontrol agents in food. To this end, phages need certain requirements to allow their manufacture and application. The aim of this study was to determine the physical stability and allergenic potential of free and microencapsulated (ME) bacteriophage cocktails against E. coli O157:H7. In vitro and in vivo studies were performed to determine phage survival under different pH, gastrointestinal conditions, temperature and UV light intensities. Results showed that the stability of ME phages was significantly (P<0.05) higher than free phages after ultraviolet irradiation, pH conditions between 3 to 7, and exposure to temperatures between at -80°C and 70°C. Both formulations were highly sensitive to very low pH in simulated gastric fluid, but stable in bile salts. In vivo studies in mice confirmed these phages passed through the gastrointestinal tract and were excreted in faeces. In silico, full-length alignment analysis showed that all phage proteins were negative for allergenic potential, but different predicting criteria classified seven phage proteins with a very low probability to be an allergen. In conclusion, these data demonstrated that microencapsulation provided a greater stability to phage formulation under stress conditions and assure a more suitable commercial formulation for the biological control of E. coli O157:H7.

Low-Temperature Virus vB_EcoM_VR26 Shows Potential in Biocontrol of STEC O26:H11

“…Taken together, the results of the pH-inactivation assay suggested that VR26 sustained its lytic property through a broad range of pHs, indicating greater stability of this phage compared with other O26:H11-infecting [ 24 ] or even O157:H7-infecting viruses [ 24 , 35 , 36 , 37 ] described in previous studies.…”

Examining the effects of an anti-Salmonella bacteriophage preparation, BAFASAL, on ex vivo human gut microbiome composition and function using a multi-omics approach

“…Oral administration of different anti- Salmonella bacteriophage mixtures into mice did not result in gross clinical changes or mortality [12, 28]. Additionally, mice treated with a bacteriophage therapeutic against E.coli also did not exhibit any toxic effects [29].…”

Biocontrol of Soft Rot Caused by Pectobacterium odoriferum with Bacteriophage phiPccP-1 in Kimchi Cabbage

“…The pH stability was tested with 10 μL phage suspension in 990 μL SM buffer solutions adjusted to pH 2, 3, 4, 5, 7, 10, 11, and 12 overnight. Stability of phage under UV radiation was tested according to a previous report [ 44 ] with a modification. Briefly, 1 mL of phage lysate (10 8 PFU ml −1 ) was added into the 24-well plate and then irradiated for 0, 15, 30, 45 and 60 min with the UV light (λ = 365 nm; 320 mW/m 2 ).…”