Yersinia enterocolitica is a gram-negative, non-spore-forming, coccobacilli, psychrotrophic, and facultative anaerobe, which is one of three Yersinia species that are pathogenic to humans, along with Y. pestis, and Y. pseudotuberculosis [1, 2]. The most predominant natural hosts for Y. enterocolitica are animals (especially pigs). Y. enterocolitica also exists ubiquitously in water, soil, plant surfaces, and foods [3]. Although animals are the major source of Y. enterocolitica, many cases have recently been reported in which outbreaks of Y. enterocolitica were associated with fresh produce such as salad, bean sprouts and leafy vegetables [4, 5]. Yersinia infection, commonly known as yersiniosis, begins with some common symptoms such as fever, diarrhea (often bloody), and abdominal pain, which is sometimes confused with appendicitis. It is also associated with some severe complications such as skin rash, meningitis, mesenteric lymphadenitis, and sepsis [2, 3]. A European Union Summary Report [6] classified yersiniosis as the third most common zoonosis in Europe [4]. Moreover, recent findings revealed that Yersinia species had developed resistance against penicillin, ampicillin, cephalosporin, and macrolides due to the production of beta-lactamases [7]. Thus, a safe, ecofriendly and effective "green" approach is required to control Y. enterocolitica to ensure food safety and public health [8]. Bacteriophages (phages) are the most abundant entities (10 3 1-10 3 2) in nature and have recently gathered more attention as green biocontrol agents owing to several advantages, including excellent target specificity, the ability to multiply in the presence of hosts, preparation and cost efficiencies, stability in wide-ranging pH levels and temperatures, and harmlessness to humans, animals, and plants [9-11]. The necessity of novel biocontrol agents has prompted us to isolate numerous phages (mainly lytic phages) from various environments and foods [12]. Unlike lysogenic phages, the lytic phage can lyse the target bacteria by integrating their DNA into the bacterial chromosome and then replicating themselves inside the host, a trait that is preferred for their use as biocontrol agents [2, 13, 14].

This study investigated the feasibility of the lytic, tailed Bacillus cereus-specific phage for use in a ferromagnetoelastic (FME) biosensor as a novel recognition element. The phage was immobilized at various concentrations through either direct adsorption or a combination of 11-mercapto-1-undecanoic acid (11-MUA) and [N-(3-dimethylaminopropyl)-N'-carbodiimide hydrochloride and N-hydroxysuccinimide (EDC/NHS)]. The effects of time and temperature on its lytic properties were investigated through the exposure of B. cereus (4 and 8 logCFU/ml) to the phage (8 logPFU/ml) for various incubation periods at 22°C and at various temperatures for 30 and 60 min. As the phage concentration increased, both immobilization methods also significantly increased the phage density (p < 0.05). SEM images confirmed that the phage density on the FME platform corresponded to the increased phage concentration. As the combination of 11-MUA and EDC/NHS enhanced the phage density and orientation by up to 4.3-fold, it was selected for use. When various incubation was conducted, no significant differences were observed in the survival rate of B. cereus within 30 min, which was in contrast to the significant decreases observed at 45 and 60 min (p < 0.05). In addition, temperature exerted no significant effects on the survival rate across the entire temperature range. This study demonstrated the feasibility of the lytic, tailed B. cereus-specific phage as a novel recognition element for use in an FME biosensor. Thus, the phage could be placed on the surface of foods for at least 30 min without any significant loss of B. cereus, as a result of the inherent lytic activity of the B. cereus-specific phage as a novel recognition element.