Food safety lessons learned from the COVID-19 pandemic.

The COVID-19 pandemic has ushered in a new era of food safety. To date, there is no evidence to suggest that consuming food is associated with COVID-19. Nevertheless, COVID-19's impact on food safety and security has been grave. The world is currently experiencing several supply chain issues as a direct result of extensive lockdowns and impacts on essential workers' safety. However, disruption in the food supply, while catastrophic in nature, has created opportunities for the advancement of medical science, data processing, security monitoring, foodborne pathogen detection, and food safety technology. This article will discuss the key components for food safety during the COVID-19 pandemic. The discussion will draw from lessons learned early in the outbreak and will analyze the etiology of the disease through a food safety perspective. From there, we will discuss personal protective equipment, detection of SARS-CoV-2, useful surrogates to study SARS-CoV-2, and the expanding field of data science, from the food safety point of view. In the future, scientists can apply the knowledge to the containment of COVID-19 and eventually to future pandemics.

A review of epidemic investigation on cold-chain food-mediated SARS-CoV-2 transmission and food safety consideration during COVID-19 pandemic.

COVID-19 has brought speculations on potential transmission routes of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causal agent of the pandemic. It is reported that the main route of virus transmission to be person-to-person by respiratory droplets; however, people have raised concerns on the possible transmission of SARS-CoV-2 to humans via food and packaging and its potential effects on food safety. This review discusses food safety issues in the COVID-19 pandemic and reveals its possible transmission in cold-chain food. The first outbreak of COVID-19 in late 2019 was associated with a seafood market in Wuhan, China, while the second outbreak of COVID-19 in June 2020 was also related to a seafood market in Beijing, China. As of 2020, several frozen seafood products linked with SARS-CoV-2 have been reported in China. According to the current survey and scientific studies, the risk of infection by SARS-CoV-2 from cold-chain food, food products, and food packaging is thought to be very low. However, studies on food cold chain contamination have shown that SARS-CoV-2 remained highly stable under refrigerated (4°C) and even in freezing conditions (-10 to -80°C). Since one mode of SARS-CoV-2 transmission appears to be touching contaminated surfaces, it is important to clean and sanitize food contact surfaces properly. Understanding food safety hazard risks is essential to avoid potential negative health effects and SARS-CoV-2 transmission in the food supply chain during the COVID-19 pandemic.

Effects of lyophilization on the stability of bacteriophages against different serogroups of Shiga toxin-producing Escherichia coli.

Lyophilization is commonly used to effectively preserve the stability of bacteriophages (phages) in long-term storage. However, information regarding the lyophilization of phages specific to Shiga toxin-producing Escherichia coli (STEC) strains is scarce. The objective of this study was to determine the effects of lyophilization with different cryoprotectants (sucrose and trehalose) and concentrations (0.1 M and 0.5 M) on the stability of seven lytic phages specific to STEC O157 and top 6 non-O157 strains during 6-month storage at -80 °C. The titers of lyophilized phages specific to STEC O26 (S1 O26) and STEC O121 (Pr121lvw) did not exhibit significant reduction after 6-month storage regardless of the use of cryoprotectants. Phages lytic against STEC O103 (Ro103C3lw) and STEC O145 (Ro145clw) with 0.1 M sucrose retained similar titers after lyophilization and frozen storage for 6 months (P > 0.05). Despite subtle differences, these results indicated that most of the selected phages had similar titer retention with the same cryoprotectants. Additionally, lytic activities of the phages against their primary hosts were not affected after lyophilization and 6-month frozen storage. Moreover, no detectable damage was observed on the lyophilized phage structures. These findings provide valuable insight into the use of lyophilization to preserve phages lytic against STEC strains.

Gaseous antimicrobial treatments to control foodborne pathogens on almond kernels and whole black peppercorns.

Gaseous treatments with ClO2 and O3 on low-moisture foods (LMFs) have been reported for their efficient bacterial reduction without affecting the external quality of food. However, these studies were conducted on a small scale, which limits their application to LMF industries. We aimed to evaluate the effectiveness of gaseous antimicrobial intervention with ClO2 or O3 to reduce foodborne pathogens (Shiga toxin-producing Escherichia coli, serovars of Salmonella enterica, and Listeria monocytogenes) inoculated on almonds and peppercorns maintained under various conditions. Almonds were treated for over 4 or 6 h. Peppercorns were treated for over 2.5 or 4 h. Gaseous O3 treatment was used for 6 h on almonds and 2 or 4 h on peppercorns. Additionally, the effects of relative humidity (RH) during the treatment of peppercorns and post-treatment heating on almonds were evaluated. Heating at 65 °C post-ClO2 treatment yielded the highest bacterial log reduction of 4.6 CFU/g on almonds, while 80% RH resulted in 3.7-log bacterial reduction on peppercorns. Gaseous O3 resulted in maximum log reductions of 1.3 and 2.5 CFU/g on almonds and peppercorns, respectively. No visual damage was observed. In conclusion, ClO2 was more efficient than O3 and the treatment can be incorporated into industrial practices.

Effectiveness of different antimicrobial washes combined with freezing against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes inoculated on blueberries.

To ensure the safety of produce, including blueberries, elimination of potential pathogens is critical. This study evaluated the efficacy of antimicrobial washes when coupled with frozen storage against Escherichia coli O157:H7, Salmonella Typhimurium and Listeria monocytogenes on wild blueberries. Inoculated blueberries were sprayed with antimicrobial solutions at different concentrations for various contact times (chlorine dioxide -2.5, 5, 10, and 15 ppm for 10 s, 1, 5, and 10 min; chlorine -100, 150, and 200 ppm for 10s, 1, 5, and 10 min; lactic acid 1 and 2% for 5, 10 and 20 min) and following treatment, stored at -12 °C for 1 week. Compared to antimicrobial washing alone, the additional freezing significantly reduced pathogens (P < 0.05). Concentrations of all three antimicrobials combined with freezing reduced L. monocytogenes to undetectable levels (detection limit < 1 log CFU/g). The greatest reduction of E. coli O157:H7 (4.4 log CFU/g) and Salmonella (5.4 log CFU/g) was achieved by 2% lactic acid or 200 ppm Cl2 followed with frozen storage. These antimicrobials maintained the visual quality of blueberries and did not leave detectable residues. In conclusion, antimicrobial washes, when combined with frozen storage, effectively reduce the risk of pathogen contamination on blueberries.

Preparation of Fish Skin Gelatin-Based Nanofibers Incorporating Cinnamaldehyde by Solution Blow Spinning.

Cinnamaldehyde, a natural preservative that can non-specifically deactivate foodborne pathogens, was successfully incorporated into fish skin gelatin (FSG) solutions and blow spun into uniform nanofibers. The effects of cinnamaldehyde ratios (5-30%, w/w FSG) on physicochemical properties of fiber-forming emulsions (FFEs) and their nanofibers were investigated. Higher ratios resulted in higher values in particle size and viscosity of FFEs, as well as higher values in diameter of nanofibers. Loss of cinnamaldehyde was observed during solution blow spinning (SBS) process and cinnamaldehyde was mainly located on the surface of resultant nanofibers. Nanofibers all showed antibacterial activity by direct diffusion and vapor release against Escherichia coli O157:H7, Salmonella typhimurium, and Listeria monocytogenes. Inhibition zones increased as cinnamaldehyde ratio increased. Nanofibers showed larger inhibition effects than films prepared by casting method when S. typhimurium was exposed to the released cinnamaldehyde vapor, although films had higher remaining cinnamaldehyde than nanofibers after preparation. Lower temperature was favorable for cinnamaldehyde retention, and nanofibers added with 10% cinnamaldehyde ratio showed the highest retention over eight-weeks of storage. Results suggest that FSG nanofibers can be prepared by SBS as carriers for antimicrobials.

Benefits of isochoric freezing for carrot juice preservation.

Isochoric freezing (IF) at -5°C/77 and -10°C/100 MPa was used to preserve carrot juice for 12 weeks. The juice qualities were compared to those using heat treatment (HT) at 95°C for 15 s followed by cold storage at 4°C. The native population of total aerobic bacteria, yeasts, and molds in isochoric frozen juice remained below the detection limit for 12 weeks. In comparison, microbes started to grow in heat-treated juices after 3 weeks of refrigeration. The color of isochoric frozen juice appeared more deep orange than the fresh juice due to an increase in carotenoid extractability. IF was not effective in reducing the activities of peroxidase, polyphenol oxidase, and pectin methyl esterase compared with HT. However, the isochoric samples showed higher carotenoid content, polyphenol content, and antioxidant capacity compared to the fresh and heat-treated juices. PRACTICAL APPLICATION: Isochoric freezing was used to produce carrot juice with extended shelf life. Isochoric freezing could be a beneficial alternative to conventional heat treatment for carrot juice processing as the applied pressures reached total inactivation levels of spoilage microorganisms. Moreover, the low processing temperatures better retained desirable compounds and quality attributes of fresh juice throughout its shelf life.

Characterization of two novel Salmonella phages having biocontrol potential against Salmonella spp. in gastrointestinal conditions.

Salmonella is a primary enteric pathogen related to the contamination of poultry and other food products in numerous foodborne outbreaks. The continuous emergence of multidrug-resistant bacteria has become a serious issue due to the overuse of antibiotics. Hence, lytic phages are considered alternative biocontrol agents against these bacterial superbugs. Here, two Salmonella phages-S4lw and D5lw-were subjected to genomic and biological characterization and further encapsulated to improve the stability under acidic conditions mimicking gastrointestinal conditions. The two lytic phages, S4lw and D5lw, taxonomically belong to new species under the Guernseyvirinae and Ackermannviridae families, respectively. Each phage showed antimicrobial activities against diverse Salmonella spp., such as S. Enteritidis and S. Typhimurium, achieving 1.7-3.4 log reduction after 2-6 h of treatment. The phage cocktail at a multiplicity of infection (MOI) of 100 or 1000 completely inhibited these Salmonella strains for at least 14 h at 25 °C. Additionally, the bead-encapsulated phage cocktail could withstand low pH and different simulated gut environments for at least 1 h. Overall, the newly isolated phages can potentially mitigate Salmonella spp. under the gastrointestinal environments through encapsulation and may be further applied via oral administration to resolve common antimicrobial resistance issues in the poultry production chain.

The effect of American cranberry (Vaccinium macrocarpon) constituents on the growth inhibition, membrane integrity, and injury of Escherichia coli O157:H7 and Listeria monocytogenes in comparison to Lactobacillus rhamnosus.

The antimicrobial properties of the American cranberry were studied against Escherichia coli O157:H7, Listeria monocytogenes, and Lactobacillus rhamnosus to determine the effects on growth inhibition, membrane permeability, and injury. Cranberry powder was separated using a C-18 Sep-Pak cartridge into sugars plus organic acids (F1), monomeric phenolics (F2), and anthocyanins plus proanthocyanidins (F3). Fraction 3 was further separated into anthocyanins (F4) and proanthocyanidins (F5) using an LH-20 Sephadex column. Each fraction was diluted in the brain heart infusion (BHI) broth to determine the minimum inhibitory/bactericidal concentrations (MIC/MBC). L. monocytogenes was the most susceptible to cranberry fraction treatment with the lowest MIC/MBC for each treatment, followed by E. coli O157:H7 and L. rhamnosus. Membrane permeability and potential was studied using LIVE/DEAD viability assay and using Bis (1, 3-dibutylbarbituric acid) trimethine oxonol (DiBAC4), respectively. L. rhamnosus demonstrated the highest permeability followed by E. coli O157:H7, and L. monocytogenes. L. rhamnosus demonstrated the highest recovery followed by E. coli O157:H7, and L. monocytogenes. Each cranberry fraction demonstrated membrane hyperpolarization at their native pH, while F2, F3, and F5 demonstrated membrane depolarization at neutral pH. With this knowledge cranberry compounds may be used to prevent maladies and potentially substitute for synthetic preservatives and antibiotics.

Phytochemicals in lowbush wild blueberry inactivate Escherichia coli O157:H7 by damaging its cell membrane.

The antimicrobial activity and model of action of polyphenolic compounds extracted from lowbush wild blueberries (LWB) were studied against Escherichia coli O157:H7. Polyphenols in LWB were extracted using 80% vol/vol methanol and designated as total blueberry phenolics (TBP). The fraction was further separated by a C-18 Sep-Pak cartridge into monomeric phenolics acids (MPA) and anthocyanins plus proanthocyanidins (A&P). The A&P fraction was further separated into anthocyanins and proanthocyanidins using a LH-20 Sephadex column. Each fraction was diluted in 0.85% wt/vol NaCl, inoculated with E. coli O157:H7 to achieve 8 log colony-forming units (CFU)/mL, and incubated at 25 °C for 1 h. The survival populations of E. coli O157:H7 in the phenolic fractions were determined by a viable cell counts method. The permeability of the cell membrane of E. coli O157:H7 was determined using LIVE/DEAD viability assay, and the damage was visualized by using transmission electron microscopy (TEM). Significant (p<0.05) reductions of 5 log CFU/mL of E. coli O157:H7 were observed for MPA at 0.4 g/L gallic acid equivalents (GAE), A&P at 0.9 g/L GAE, and anthocyanins at 0.65 g/L GAE. Reductions of 6-7 CFU/mL were observed for MPA at 0.8 g/L GAE, A&P at 1.8 g/L GAE, and anthocyanins at 1.3 g/L GAE compared to the control. The cell membrane of E. coli O157:H7 exhibited a significantly increased permeability when treated with proanthocyanidins (0.15 g/L GAE), A&P (0.45 g/L GAE), anthocyanins (0.65 g/L GAE), and TBP (0.14 g/L GAE). TEM confirmed the inactivation and increased membrane permeability of E. coli O157:H7. This study demonstrated the antimicrobial effect of polyphenols from LWB against E. coli O157:H7 and the probable mode of action.

The Role of Temperate Phages in Bacterial Pathogenicity.

Bacteriophages are viruses that infect bacteria and archaea and are classified as virulent or temperate phages based on their life cycles. A temperate phage, also known as a lysogenic phage, integrates its genomes into host bacterial chromosomes as a prophage. Previous studies have indicated that temperate phages are beneficial to their susceptible bacterial hosts by introducing additional genes to bacterial chromosomes, creating a mutually beneficial relationship. This article reviewed three primary ways temperate phages contribute to the bacterial pathogenicity of foodborne pathogens, including phage-mediated virulence gene transfer, antibiotic resistance gene mobilization, and biofilm formation. This study provides insights into mechanisms of phage-bacterium interactions in the context of foodborne pathogens and provokes new considerations for further research to avoid the potential of phage-mediated harmful gene transfer in agricultural environments.

Gut Phageome-An Insight into the Role and Impact of Gut Microbiome and Their Correlation with Mammal Health and Diseases.

The gut microbiota, including bacteria, archaea, fungi, and viruses, compose a diverse mammalian gut environment and are highly associated with host health. Bacteriophages, the viruses that infect bacteria, are the primary members of the gastrointestinal virome, known as the phageome. However, our knowledge regarding the gut phageome remains poorly understood. In this review, the critical role of the gut phageome and its correlation with mammalian health were summarized. First, an overall profile of phages across the gastrointestinal tract and their dynamic roles in shaping the surrounding microorganisms was elucidated. Further, the impacts of the gut phageome on gastrointestinal fitness and the bacterial community were highlighted, together with the influence of diets on the gut phageome composition. Additionally, new reports on the role of the gut phageome in the association of mammalian health and diseases were reviewed. Finally, a comprehensive update regarding the advanced phage benchwork and contributions of phage-based therapy to prevent/treat mammalian diseases was provided. This study provides insights into the role and impact of the gut phagenome in gut environments closely related to mammal health and diseases. The findings provoke the potential applications of phage-based diagnosis and therapy in clinical and agricultural fields. Future research is needed to uncover the underlying mechanism of phage-bacterial interactions in gut environments and explore the maintenance of mammalian health via phage-regulated gut microbiota.

Metagenomic investigation reveals bacteriophage-mediated horizontal transfer of antibiotic resistance genes in microbial communities of an organic agricultural ecosystem.

Agricultural microbiomes are major reservoirs of antibiotic resistance genes (ARGs), posing continuous risks to human health. To understand the role of bacteriophages as vehicles for the horizontal transfer of ARGs in the agricultural microbiome, we investigated the diversity of bacterial and viral microbiota from fecal and environmental samples on an organic farm. The profiles of the microbiome indicated the highest abundance of Bacteroidetes, Firmicutes, and Proteobacteria phyla in animal feces, with varying Actinobacteria and Spirochaetes abundance across farm animals. The most predominant composition in environmental samples was the phylum Proteobacteria. Compared to the microbiome profiles, the trends in virome indicated much broader diversity with more specific signatures between the fecal and environmental samples. Overall, viruses belonging to the order Caudovirales were the most prevalent across the agricultural samples. Additionally, the similarities within and between fecal and environmental components of the agricultural environment based on ARG-associated bacteria alone were much lower than those of total microbiome composition. However, there were significant similarities in the profiles of ARG-associated viruses across the fecal and environmental components. Moreover, the predictive models of phage-bacterial interactions on bipartite ARG transfer networks indicated that phages belonging to the order Caudovirales, particularly in the Siphoviridae family, contained diverse ARG types in different samples. Their interaction with various bacterial hosts further implied the important role of bacteriophages in ARG transmission across bacterial populations. Our findings provided a novel insight into the potential mechanisms of phage-mediated ARG transmission and their correlation with resistome evolution in natural agricultural environments. IMPORTANCE Antibiotic resistance has become a serious health concern worldwide. The potential impact of viruses, bacteriophages in particular, on spreading antibiotic resistance genes is still controversial due to the complexity of bacteriophage-bacterial interactions within diverse environments. In this study, we determined the microbiome profiles and the potential antibiotic resistance gene (ARG) transfer between bacterial and viral populations in different agricultural samples using a high-resolution analysis of the metagenomes. The results of this study provide compelling genetic evidence for ARG transfer through bacteriophage-bacteria interactions, revealing the inherent risks associated with bacteriophage-mediated ARG transfer across the agricultural microbiome.

A new Rogue-like Escherichia phage UDF157lw to control Escherichia coli O157:H7.

Introduction: Shiga toxin-producing Escherichia coli (STEC) O157:H7 is one of the notorious foodborne pathogens causing high mortality through the consumption of contaminated food items. The food safety risk from STEC pathogens could escalate when a group of bacterial cells aggregates to form a biofilm. Bacterial biofilm can diminish the effects of various antimicrobial interventions and enhance the pathogenicity of the pathogens. Therefore, there is an urgent need to have effective control measurements. Bacteriophages can kill the target bacterial cells through lytic infection, and some enzymes produced during the infection have the capability to penetrate the biofilm for mitigation compared to traditional interventions. This study aimed to characterize a new Escherichia phage vB_EcoS-UDF157lw (or UDF157lw) and determine its antimicrobial efficacy against E. coli O157:H7. Methods: Phage characterization included biological approaches, including phage morphology, one-step growth curve, stability tests (pH and temperature), and genomic approaches (whole-genome sequencing). Later, antimicrobial activity tests, including productive infection against susceptible bacterial strains, in vitro antimicrobial activity, and anti-biofilm, were conducted. Results: UDF157lw is a new member of the phages belonging to the Rogunavirus genus, comprising a long and non-contractile tail, isolated from bovine feces and shares close genomic evolutionary similarities with Escherichia phages vB_EcoS-BECP10 and bV_EcoS_AKS96. When used against E. coli O157:H7 (ATCC35150), phage UDF157lw exhibited a latent period of 14 min and a burst size of 110 PFU per infected cell. The phage remained viable in a wide range of pH values (pH 4-11) and temperatures (4-60°C). No virulence genes, such as stx, lysogenic genes, and antibiotic resistance genes, were found. Phage UDF157lw demonstrated high infection efficiencies against different E. coli O157:H7 and generic E. coli strains. In addition, UDF157lw encoded a unique major tail protein (ORF_26) with prominent depolymerase enzyme activity against various E. coli O157:H7 strains, causing large plaque sizes. In contrast to the phage without encoding depolymerase gene, UDF157lw was able to reduce the 24-h and 48-h E. coli O157:H7 biofilm after 1-h phage treatment. Discussion: The findings of this study provide insights into a new member of the Rogunavirus phages and demonstrate its antimicrobial potential against E. coli O157:H7 in vitro.

Reduction of Aspergillus flavus and aflatoxin on almond kernels using gaseous chlorine dioxide fumigation.

The almond industry suffers product losses caused by mold growth and toxin contamination. Gaseous chlorine dioxide (ClO2) has the potential for postharvest reduction of mycotoxic Aspergillus flavus. In this study, almonds inoculated with A. flavus were fumigated with gaseous ClO2 for 1, 2, 3, 8, 12, and 24 h using a dry precursor sachet batch method. The headspace concentration ranged from 0.5 to 2.4 mg/L, depending on initial dosing and time. At its highest concentration, gaseous ClO2 demonstrated an 84.4 % degradation efficiency of aflatoxin B1 (AFB1) with a reduction of 2.4 log CFU/g of A. flavus on almond kernels. Additionally, suppression of AFB1 continued after one-month storage at 4 °C. No significant oxidative effect and color difference (ΔE) was observed on the treated kernels. The almond industry can apply gaseous ClO2 technology to reduce mold contamination and product losses.

The antimicrobial properties of the lowbush blueberry (Vaccinium angustifolium) fractional components against foodborne pathogens and the conservation of probiotic Lactobacillus rhamnosus.

The antimicrobial properties of lowbush blueberry (Vaccinium angustifolium) were studied against Escherichia coli O157:H7, Listeria monocytogenes, Salmonella Typhimurium, and Lactobacillus rhamnosus to determine which fractional components have antimicrobial effects and which microorganisms are most susceptible to these antimicrobial properties. Lowbush blueberry extract (F1) was separated using a C-18 Sep-Pak cartridge into monomeric phenolics (F2) and anthocyanins plus proanthocyanidins (F3). Fraction 3 was further separated into anthocyanins (F4) and proanthocyanidins (F5) using a LH-20 Sephadex column. Each fraction was initially screened for antimicrobial properties using agar diffusion assay. Treatments that demonstrated inhibition were further analyzed for inhibition in liquid culture. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined using a two-fold dilution series and viable cell counts taken at 0 and 24 h to examine growth reduction. Fraction 3 demonstrated the lowest MICs/MBCs followed by F1, F2, F4, and F5. L. monocytogenes was the most susceptible to blueberry fraction treatment, followed by E. coli O157:H7, and S. Typhimurium. L. rhamnosus was the least susceptible to each fraction treatment. The results can be applied to the field of preventive medicine, food safety, and enrich the understanding of the health benefits of lowbush blueberries.

Fundamental Differences in Inactivation Mechanisms of Escherichia coli O157:H7 Between Chlorine Dioxide and Sodium Hypochlorite.

Chlorine dioxide (ClO2) and sodium hypochlorite (NaClO) are two chlorinated oxidizing agents that are implemented in water treatment and postharvest processing of fresh produce. While the antibacterial mechanisms of NaClO have been investigated, there are comparatively few studies that have looked at how ClO2 kills bacteria. Therefore, the objective of this study was to compare the inactivation pathways of ClO2 and NaClO against Escherichia coli O157:H7. Treatments consisted of 2.5, 5, and 10 ppm ClO2 or 50, 100, and 200 ppm NaClO for 5, 10, and 15 min. Maximum log reductions of E. coli O157:H7 were 5.5 and 5.1 after treatment with ClO2 or NaClO, respectively. Bacterial inactivation was measured using log reductions, intracellular reactive oxygen species (ROS) using with 2',7'-dichlorofluorescin diacetate (DCFDA) or aminophenyl fluorescein (APF) probes, relative values of NAD+, NADH, NADP+, and NADPH cofactors. Additionally, the expression of three key genes involved in ROS stress was measured via RT-PCR. Levels of intracellular ROS measured by DCFDA after ClO2 treatment were significantly higher than those found after treatment in NaClO. Additionally, NaClO treatment resulted in upregulation of ROS-defense genes, while expression of the same genes was typically at base levels or downregulated after ClO2 treatment. As the concentrations of both treatments increased, the NADP+:NADPH ratio shifted to the cofactor being predominantly present as NADP+. These data indicate that ClO2 and NaClO damage E. coli O157:H7 via measurably different mechanisms and that ClO2 does not appear to cause substantial oxidative stress to E. coli O157:H7 directly.

Characterization of a T4-like Bacteriophage vB_EcoM-Sa45lw as a Potential Biocontrol Agent for Shiga Toxin-Producing Escherichia coli O45 Contaminated on Mung Bean Seeds.

Application of lytic bacteriophages is a promising and alternative intervention technology to relieve antibiotic resistance pressure and control bacterial pathogens in the food industry. Despite the increase of produce-associated outbreaks caused by non-O157 Shiga toxin-producing E. coli (STEC) serogroups, the information of phage application on sprouts to mitigate these pathogens is lacking. Therefore, the objective of this study was to characterize a T4-like Escherichia phage vB_EcoM-Sa45lw (or Sa45lw) for the biocontrol potential of STEC O45 on mung bean seeds. Phage Sa45lw belongs to the Tequatrovirus genus under the Myoviridae family and displays a close evolutionary relationship with a STEC O157-infecting phage AR1. Sa45lw contains a long-tail fiber gene (gp37), sharing high genetic similarity with the counterpart of Escherichia phage KIT03, and a unique tail lysozyme (gp5) to distinguish its host range (STEC O157, O45, ATCC 13706, and Salmonella Montevideo and Thompson) from phage KIT03 (O157 and Salmonella enterica). No stx, antibiotic resistance, and lysogenic genes were found in the Sa45lw genome. The phage has a latent period of 27 min with an estimated burst size of 80 PFU/CFU and is stable at a wide range of pH (pH 3 to pH 10.5) and temperatures (-80°C to 50°C). Phage Sa45lw is particularly effective in reducing E. coli O45:H16 both in vitro (MOI = 10) by 5 log and upon application (MOI = 1,000) on the contaminated mung bean seeds for 15 min by 2 log at 25°C. These findings highlight the potential of phage application against non-O157 STEC on sprout seeds. IMPORTANCE Seeds contaminated with foodborne pathogens, such as Shiga toxin-producing E. coli, are the primary sources of contamination in produce and have contributed to numerous foodborne outbreaks. Antibiotic resistance has been a long-lasting issue that poses a threat to human health and the food industry. Therefore, developing novel antimicrobial interventions, such as bacteriophage application, is pivotal to combat these pathogens. This study characterized a lytic bacteriophage Sa45lw as an alternative antimicrobial agent to control pathogenic E. coli on the contaminated mung bean seeds. The phage exhibited antimicrobial effects against both pathogenic E. coli and Salmonella without containing virulent or lysogenic genes that could compromise the safety of phage application. In addition, after 15 min of phage treatment, Sa45lw mitigated E. coli O45:H16 on the contaminated mung bean seeds by a 2-log reduction at room temperature, demonstrating the biocontrol potential of non-O157 Shiga toxin-producing E. coli on sprout seeds.

Advances, applications, and limitations of portable and rapid detection technologies for routinely encountered foodborne pathogens.

Traditional foodborne pathogen detection methods are highly dependent on pre-treatment of samples and selective microbiological plating to reliably screen target microorganisms. Inherent limitations of conventional methods include longer turnaround time and high costs, use of bulky equipment, and the need for trained staff in centralized laboratory settings. Researchers have developed stable, reliable, sensitive, and selective, rapid foodborne pathogens detection assays to work around these limitations. Recent advances in rapid diagnostic technologies have shifted to on-site testing, which offers flexibility and ease-of-use, a significant improvement from traditional methods' rigid and cumbersome steps. This comprehensive review aims to thoroughly discuss the recent advances, applications, and limitations of portable and rapid biosensors for routinely encountered foodborne pathogens. It discusses the major differences between biosensing systems based on the molecular interactions of target analytes and biorecognition agents. Though detection limits and costs still need further improvement, reviewed technologies have high potential to assist the food industry in the on-site detection of biological hazards such as foodborne pathogens and toxins to maintain safe and healthy foods. Finally, this review offers targeted recommendations for future development and commercialization of diagnostic technologies specifically for emerging and re-emerging foodborne pathogens.

A New Kayfunavirus-like Escherichia Phage vB_EcoP-Ro45lw with Antimicrobial Potential of Shiga Toxin-Producing Escherichia coli O45 Strain.

Lytic bacteriophages are re-considered as a solution to resolve antibiotic-resistant rampage. Despite frequent foodborne outbreaks caused by the top six non-O157 Shiga-toxin-producing Escherichia coli (STEC), the current interventions are not sufficiently effective against each serogroup, particularly O45. Therefore, this study aimed to characterize a new short-tailed phage, vB_EcoP-Ro45lw (or Ro45lw), as an alternative antimicrobial agent for STEC O45 strains. Phage Ro45lw belongs to the Kayfunavirus genus within the Autographiviridae family and shares no close evolutionary relationship with any reference phages. Ro45lw contains a tail structure composed of a unique tail fiber and tail tubular proteins A and B, likely to produce enzymatic activity against the target bacterial cells besides structural function. Additionally, the phage genome does not contain virulent, antibiotic-resistant, or lysogenic genes. The phage has a latent period of 15 min with an estimated burst size of 55 PFU/CFU and is stable at a wide range of pH (pH4 to pH11) and temperatures (30 °C to 60 °C). Regardless of the MOIs (MOI = 0.1, 1, and 10) used, Ro45lw has a strong antimicrobial activity against both environmental (E. coli O45:H-) and clinical (E. coli O45:H2) strains at 25 °C. These findings indicate that phage Ro45lw has antimicrobial potential in mitigating pathogenic STEC O45 strains.