The antibacterial effect of chitosan‐based edible coating incorporated with a lytic bacteriophage against Escherichia coli O157:H7 on the surface of tomatoes

Abstract

Edible coating can be used as carriers of bacteriophages, whose release into the food surface could control bacterial growth. The aim of the study was to isolate and characterize bacteriophages against a wide range of E. coli strains. Furthermore, the efficacy of chitosan‐based edible coating incorporated with a lytic bacteriophage in the biological control of E. coli on the surface of tomatoes was evaluated and discussed. Three phages were isolated from raw beef and goat stool samples, and were characterized by host range, virion structure, and DNA restriction profiles. Analysis by electron microscopy revealed that the three phages belong to the Caudovirales order. Based on the host range of the phages, they have wide infection abilities against the Enterobacteriaceae family. Phages isolated have dsDNA genomes at about 40 kbp according to restriction digest of complete phage genome. The results demonstrate that the chitosan‐based edible coating can stabilize phage vB_EcoMH2W without significant loss in lytic activity of phage over a period of one week. Moreover, the results of bacterial growth analysis showed an approximately 3 log differences in microbial levels between the control and the treatment samples. Therefore, chitosan as edible coating would enhance the microbial safety of foods during storage. Practical applications The development of functional edible coatings formulations incorporated with antimicrobial agents to minimize the risk of foodborne contamination by pathogens, inactivate pathogens present in the food, and limit pathogen growth is an environmentally friendly alternative that offers substantial advantages. Several antimicrobial agents, including phages, that can be incorporated into edible coating as packaging strategy to reducing levels of pathogenic bacterial. The edible coating incorporated with lytic phages have several potential applications in the food industry as a natural method for biocontrol of food‐borne pathogens, which can be released into the food slowly and steadily extending the antimicrobial activity.

Entrapment of a phage cocktail and cinnamaldehyde on sodium alginate emulsion-based films to fight food contamination by Escherichia coli and Salmonella Enteritidis

“…More recently, studies have reported phages encapsulation to be further applied in food products. For instance, the incorporation of phages targeting E. coli strains into matrices such as whey protein isolate (WPI) coatings/films (Huang & Nitin, 2019;Tomat et al, 2019;Vonasek, Choi, Sanchez, & Nitin, 2018) or chitosan (Amarillas et al, 2018) has proved to reduce the loss of phage activity during storage and to be a highly effective to prevent bacterial contamination of vegetable surfaces, meat, fish feed and tomatoes. A cocktail of phages targeting Salmonella has also been microencapsulated in WPI coatings and exhibited a high efficiency against Salmonella serovars, but it was less efficient when applied on fresh foods (Petsong, Benjakul, & Vongkamjan, 2019).…”

Identification and characterization of lytic bacteriophages specific to foodborne pathogenicEscherichia coliO157:H7

“…Many researchers have reported that E. coli O157:H7 bacteriophages usually are members of the Myoviridae and Siphoviridae families (Amarillas et al., 2018; Litt and Jaroni, 2017; Niu et al., 2014; Topka et al., 2019). Litt and Jaroni (2017) reported that seven phages (P-1 to P-7) which were specific to E. coli O157:H7 formed medium-sized (0.3–0.5 mm in diameter) clear plaques on the lawn of its host bacteria.…”

“…Litt and Jaroni (2017) reported that seven phages (P-1 to P-7) which were specific to E. coli O157:H7 formed medium-sized (0.3–0.5 mm in diameter) clear plaques on the lawn of its host bacteria. The plaque sizes of vB_EcoM34X, vB_EcoSH2Q, and vB_EcoMH2W phages were around 1.5 mm, 1.0 mm, and 2.0 mm larger after 18 h for phages, respectively (Amarillas et al., 2018).…”

Encapsulation Systems for Antimicrobial Food Packaging Components: An Update

“…Therefore, bacteriophages have great potential to be applied by the food industry as antimicrobial agents incorporated directly into food products or through their incorporation into the food packaging material for a more controlled release [30]. So far, packaging materials containing bacteriophages have proven to effectively control several foodborne pathogens, including Salmonella enterica, Listeria monocytogenes and Escherichia coli O157:H7 ( Table 1).…”