Antibacterial effect of Moringa oleifera on Staphylococcus aureus and Pseudomonas aeruginosa isolated from raw milk and some dairy products with special reference to biofilm gene expression.

Background: Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus) are well defined as food poisoning pathogens that are highly resistant and need continuous studies. Aim: The purpose of the work was to examine phenotypic and genotypic characteristics of both P. aeruginosa and S. aureus, and treatment trials with medicinal plants. Methods: Samples were examined for isolation of P. aeruginosa and S. aureus on selective media followed by biochemical confirmation, biofilm formation, genes detection, and expression of P. aeruginosa pslA biofilm gene was performed by quantitative real-time polymerase chain reaction after treatment with 0.312 mg/ml Moringa oleifera aqueous extract as a minimum inhibitory concentration. Results: The highest isolation rate of P. aeruginosa was 20% from both raw milk and Kariesh cheese, followed by 16% and 12% from ice cream and processed cheese, respectively, while the highest isolation rate of S. aureus was 36% from raw milk followed by 28% in ice cream and 16% in both Kariesh cheese and processed cheese. 30% of P. aeruginosa isolates were biofilm producers, while only 21% of S. aureus isolates were able to produce biofilm. The P. aeruginosa isolates harbor virulence-associated genes nan1, exoS, toxA, and pslA at 100%, 80%, 40%, and 40%, respectively. Staphylococcus aureus SEs genes were examined in S. aureus strains, where SEA and SEB genes were detected with 60%, but no isolate harbored SEC, SED, or SEE. The significant fold change of P. aeruginosa pslA expression was 0.40332 after treatment with M. oleifera aqueous extract. Conclusion: Pseudomonas aeruginosa and S. aureus harbor dangerous virulence genes that cause food poisoning, but M. oleifera extract could minimize their action.

Peracetic acid application as an antimicrobial and its residual (HEDP): a holistic approach on the technological characteristics of chicken meat.

The most significant occurrence of food-borne diseases is due to Campylobacter and Salmonella contamination from chicken meat, and for this reason, strict regulations about strategies to improve the control of food pathogens are imposed by food safety authorities. Despite the efforts of poultry industry since the beginning of risk analysis and critical control point to reduce the burden of food-borne illness, technological barriers along the way are increasingly necessary to ensure safe food. The aim of this review was to carry out a scientific approach to the influence of peracetic acid (PAA) as an antimicrobial and its toxicological safety, in particular the stabilizer used in the formulation of PAA, 1-hydroxyethylidene 1,1-diphosphonic acid (HEDP), suggesting the possibility of researching the residual HEDP in meat, which would allow the approval of the PAA by the health authorities of several countries that still restrict it. This review also aims to ascertain the effectiveness of PAA, in different cuts and carcasses, by different application methods, comparing the effectiveness of this antimicrobial with other antimicrobials, and its exclusive or combined use, for the decontamination of poultry carcasses and raw parts. The literature results support the popularity of PAA as an effective intervention against pathogenic bacteria during poultry processing.

Investigation of a Multistate Outbreak of Listeria monocytogenes Infections Linked to Frozen Vegetables Produced at Individually Quick-Frozen Vegetable Manufacturing Facilities.

In 2016, the U.S. Food and Drug Administration (FDA), the Centers for Disease Control and Prevention (CDC), and state partners investigated nine Listeria monocytogenes infections linked to frozen vegetables. The investigation began with two environmental L. monocytogenes isolates recovered from Manufacturer A, primarily a processor of frozen onions, that were a match by whole genome sequencing (WGS) to eight clinical isolates and historical onion isolates with limited collection details. Epidemiologic information, product distribution, and laboratory evidence linked suspect food items, including products sourced from Manufacturer B, also a manufacturer of frozen vegetable/fruit products, with an additional illness. The environmental isolates were obtained during investigations at Manufacturers A and B. State and federal partners interviewed ill people, analyzed shopper card data, and collected household and retail samples. Nine ill persons between 2013 and 2016 were reported in four states. Of four ill people with information available, frozen vegetable consumption was reported by three, with shopper cards confirming purchases of Manufacturer B brands. Two identified outbreak strains of L. monocytogenes (Outbreak Strain 1 and Outbreak Strain 2) were a match to environmental isolates from Manufacturer A and/or isolates from frozen vegetables recovered from open and unopened product samples sourced from Manufacturer B; the investigation resulted in extensive voluntary recalls. The close genetic relationship between isolates helped investigators determine the source of the outbreak and take steps to protect public health. This is the first known multistate outbreak of listeriosis in the United States linked to frozen vegetables and highlights the significance of sampling and WGS analyses when there is limited epidemiologic information. Additionally, this investigation emphasizes the need for further research regarding food safety risks associated with frozen foods.

Local and Traditional Ecological Knowledge of Fish Poisoning in Fiji.

Fish poisoning (FP) affects human health, trade and livelihood in Fiji, where management has depended mainly on traditional ecological knowledge (TEK). This paper investigated and documented this TEK through a 2-day stakeholder workshop, group consultation, in-depth interviews, field observations, and analyses of survey data from the Ministry of Fisheries, Fiji. Six TEK topics were identified and classified as preventative and treatment options. The preventive approach involves identifying toxic reef fishes, the spawning season of edible seaworms, hotspot areas of toxic fishes, folk tests, and locating and removing toxic organs. For example, 34 reef fish species were identified as toxic. The FP season was associated with the spawning of balolo (edible seaworm) and the warmer months of October to April (cyclone seasons). Two well-known toxic hotspots associated with an abundance of bulewa (soft coral) were identified. Folk tests and locating and removing toxic fish organs are also practised for moray eels and pufferfish. At the same time, various locally available herbal plants are used to treat FP as the second line of defence. The TEK collated in this work can help local authorities better identify the sources of toxicity, and applying TEK preventive measures could stem the tide of fish poisoning in Fiji.

Prevalence of cpe-positive Clostridium perfringens in surface-attached soil of commercially available potatoes and its significance as a potential source of food poisoning.

OBJECTIVE: We aimed to examine the surface-attached soil of commercially available potatoes in Japan to determine the association between foodborne infection and the circulation of Clostridium perfringens through vegetables, soil, and environments. METHODS: C. perfringens spores were isolated from 30 surface-attached soil samples of potatoes obtained from six regions in Japan. We performed multiplex polymerase chain reaction (PCR) and sequencing to detect the presence of six toxin and plasmid-related genes in the isolates. RESULTS: Sulfite-reducing clostridial spores were detected in 28 (93%) of 30 potato samples, and toxin gene PCR was performed using 613 isolates. The C. perfringens α toxin gene (cpa) was detected in 288 isolates (288/613; 47%) from 25 potato samples (83%), and these isolates were presumed to be the strains of C. perfringens. The toxin types of C. perfringens were classified into type A, in which 73% of isolates had only cpa, followed by type F in 20%, type C in 6%, and type E in 0.003% (1 isolate). The enterotoxin gene (cpe) related to food poisoning was detected in 64 isolates from 9 potato samples (3%). Of these, 59 isolates had cpa and cpe, whereas five had cpa, C. perfringens ß toxin gene, and cpe. All tested cpe-positive isolates had plasmid-type cpe. CONCLUSIONS: The isolation of culturable cpe-positive C. perfringens from the surface-attached soil of commercially available potatoes indicates that potatoes are a potential source of foodborne transmission of C. perfringens.

Current Status and Future Trends in Removal, Control, and Mitigation of Algae Food Safety Risks for Human Consumption.

With the rapid development of the economy and productivity, an increasing number of citizens are not only concerned about the nutritional value of algae as a potential new food resource but are also, in particular, paying more attention to the safety of its consumption. Many studies and reports pointed out that analyzing and solving seaweed food safety issues requires holistic and systematic consideration. The three main factors that have been found to affect the food safety of algal are physical, chemical, and microbiological hazards. At the same time, although food safety awareness among food producers and consumers has increased, foodborne diseases caused by algal food safety incidents occur frequently. It threatens the health and lives of consumers and may cause irreversible harm if treatment is not done promptly. A series of studies have also proved the idea that microbial contamination of algae is the main cause of this problem. Therefore, the rapid and efficient detection of toxic and pathogenic microbial contamination in algal products is an urgent issue that needs to be addressed. At the same time, two other factors, such as physical and chemical hazards, cannot be ignored. Nowadays, the detection techniques are mainly focused on three major hazards in traditional methods. However, especially for food microorganisms, the use of traditional microbiological control techniques is time-consuming and has limitations in terms of accuracy. In recent years, these two evaluations of microbial foodborne pathogens monitoring in the farm-to-table chain have shown more importance, especially during the COVID-19 pandemic. Meanwhile, there are also many new developments in the monitoring of heavy metals, algal toxins, and other pollutants. In the future, algal food safety risk assessment will not only focus on convenient, rapid, low-cost and high-accuracy detection but also be connected with some novel technologies, such as the Internet of Things (artificial intelligence, machine learning), biosensor, and molecular biology, to reach the purpose of simultaneous detection.

Inhibition of the sea Gene Expression in Staphylococcus aureus Using the Aqueous and Alcoholic Extracts of the Grapevine (Vitis vinifera L.) Seeds.

Staphylococcus aureus is an important etiological agent for causing food poisoning leading to high mortality in the world. The sea gene is encoded in a polymorphic family of temperate bacteriophage chromosomes and became a prophage, and the transcription of this gene is associated with the life cycle of this prophage. It has been suggested that the grape polyphenols can eradicate the enterotoxin production of food-borne bacteria. This study aimed to evaluate the activity of the aqueous and alcoholic extracts of the grape seeds in inhibiting the expression of the sea gene encoding staphylococcal enterotoxin type A in S. aureus isolated from different sources. This study used five enterotoxin A producing isolates belonging to S. aureus. The results showed that minimum inhibition concentration and sub-minimum inhibition concentration of the aqueous extract were 32 and 16 µg/mL for all isolates, respectively. However, in the case of the alcoholic extract, these concentrations were 16 and 8 µg/mL for all isolates, respectively, and the results of the chemical analysis of the aqueous and alcoholic extracts confirmed that they contain active chemical compounds, such as flavonoids, alkaloids, tannins, and glycosides; moreover, they contain many functional groups according to the analysis of the infrared spectrum. Both extracts were shown to be active in inhibiting the expression of the sea gene in the isolates under study. As the results indicated, the gene expression of these isolates was inhibited by approximately 0.31-0.63 fold, and all pathogenic and environmental isolates showed a decrease in the expression of this gene. These results practically open the door to the possibility of using these extracts to inhibit the ability of S. aureus to produce these dangerous enterotoxins; thereby decreasing or preventing their pathogenicity, especially their food poisoning infections.

Ameliorative effect of nanocurcumin and Saccharomyces cell wall alone and in combination against aflatoxicosis in broilers.

BACKGROUND: The adverse effect of aflatoxin in broilers is well known. However, dietary supplementation of Saccharomyces cell wall and/or Nanocurcumin may decrease the negative effect of aflatoxin B1 because of the bio-adsorbing feature of the functional ingredients in Yeast Cell Wall and the detoxification effect of curcumin nanoparticles. The goal of this study was to see how Saccharomyces cell wall/Nanocurcumin alone or in combination with the aflatoxin-contaminated diet ameliorated the toxic effects of aflatoxin B1 on broiler development, blood and serum parameters, carcass traits, histology, immune histochemistry, liver gene expression, and aflatoxin residue in the liver and muscle tissue of broilers for 35 days. Moreover, the withdrawal time of aflatoxin was measured after feeding the aflatoxicated group an aflatoxin-free diet. Broiler chicks one day old were distributed into five groups according to Saccharomyces cell wall and/or nanocurcumin with aflatoxin supplementation. The G1 group was given a formulated diet without any supplements. The G2 group was supplemented with aflatoxin (0.25 mg/kg diet) in the formulated diet. The G3 group was supplemented with aflatoxin (0.25 mg/kg diet) and Saccharomyces cell wall (1 kg/ton diet) in the formulated diet. The G4 group was supplemented with aflatoxin (0.25 mg/kg diet) and nanocurcumin (400 mg/kg) in the formulated diet. The G5 group was supplemented with aflatoxin (0.25 mg/kg diet) and Saccharomyces cell wall (1 kg/ton diet) in combination with nanocurcumin (200 mg/kg) in the formulated diet. RESULTS: According to the results of this study, aflatoxin supplementation had a detrimental impact on the growth performance, blood and serum parameters, carcass traits, and aflatoxin residue in the liver and muscle tissue of broilers. In addition, aflatoxin supplementation led to a liver injury that was indicated by serum biochemistry and pathological lesions in the liver tissue. Moreover, the shortening of villi length in aflatoxicated birds resulted in a decrease in both the crypt depth ratio and the villi length ratio. The expression of CYP1A1 and Nrf2 genes in the liver tissue increased and decreased, respectively, in the aflatoxicated group. In addition, the aflatoxin residue was significantly (P ≤ 0.05) decreased in the liver tissue of the aflatoxicated group after 2 weeks from the end of the experiment. CONCLUSION: Saccharomyces cell wall alone or with nanocurcumin attenuated these negative effects and anomalies and improved all of the above-mentioned metrics.

Recent paradigm shifts in the perception of the role of Bacillus thuringiensis in foodborne disease.

Plant protection products based on Bacillus thuringiensis have been used to fight agricultural pests for decades and are the world's most frequently applied biopesticide. However, there is growing concern that B. thuringiensis residues in food may occasionally cause diarrheal illness in humans. This has recently sparked a plethora of research activities and vivid discussions across the scientific community, competent authorities, and the public. To support this discussion, we provide a structured overview of the current knowledge on the role of B. thuringiensis as a causative agent of foodborne infections in humans and pinpoint research gaps that need to be addressed for improved risk assessment. We review (i) recent taxonomic changes in the B. cereus group; (ii) the role of B. thuringiensis in transforming agrosystems; and (iii) key considerations for assessing the hazard potential of B. thuringiensis strains detected in foods. We conclude that (i) the taxonomy of the B. cereus group is collapsing, (ii) B. thuringiensis based biopesticides play a key role in realizing the UN's sustainable development goals, and (iii) risk assessment needs to move from taxonomy-driven considerations to strain-specific identification of virulence and pathogenicity traits We also provide an overview of relevant risk-related data for commonly used biopesticide strains.

Foodborne Toxigenic Agents Investigated in Central Italy: An Overview of a Three-Year Experience (2018-2020).

Foodborne diseases (FBDs) represent a worldwide public health issue, given their spreadability and the difficulty of tracing the sources of contamination. This report summarises the incidence of foodborne pathogens and toxins found in food, environmental and clinical samples collected in relation to diagnosed or suspected FBD cases and submitted between 2018 and 2020 to the Food Microbiology Unit of the Istituto Zooprofilattico Sperimentale del Lazio e della Toscana (IZSLT). Data collected from 70 FBD investigations were analysed: 24.3% of them started with an FBD diagnosis, whereas a further 41.4% involved clinical diagnoses based on general symptomatology. In total, 5.6% of the 340 food samples analysed were positive for the presence of a bacterial pathogen, its toxins or both. Among the positive samples, more than half involved meat-derived products. Our data reveal the probable impact of the COVID-19 pandemic on the number of FBD investigations conducted. In spite of the serious impact of FBDs on human health and the economy, the investigation of many foodborne outbreaks fails to identify the source of infection. This indicates a need for the competent authorities to continue to develop and implement a more fully integrated health network.

A novel approach using growth curve analysis to distinguish between antimicrobial and anti-biofilm activities against Salmonella.

Salmonella spp. are a commonly identified cause of outbreaks of food-borne diseases. Despite much research, there remains the need to find new antimicrobial and anti-biofilm agents against Salmonella. For this, it is necessary to distinguish between these two aspects. Agents that influence biofilm formation should not affect bacterial growth, to thus avoid further promotion of the development of resistance. In this study, we present the use of growth curves of Salmonella Infantis to simultaneously determine antimicrobial and anti-biofilm activities, for the screening for anti-Salmonella activities of 42 aqueous fungal extracts. The extract from Pseudohydnum gelatinosum showed good antimicrobial activity, and that from Pleurotus ostreatus showed good anti-biofilm activity. In extracts from Infundibulicybe geotropa and Infundibulicybe gibba, both activities were determined after fractionation. The antimicrobial activity was associated with protein-rich fractions and mediated by l-amino acid oxidase activity. The fractionation did not allow determination of the anti-biofilm active fraction, so further studies are needed to define these compounds. Growth curve analysis of S. Infantis is shown here to provide a fast and simple approach to distinguish between antimicrobial and anti-biofilm activities in a high-throughput setting, such that it can be easily implemented in screening and further bioassay-based purification of novel alternatives to antibiotics.

Biofabrication of ZnO nanoparticles using Acacia arabica leaf extract and their antibiofilm and antioxidant potential against foodborne pathogens.

Emergence of multidrug resistant pathogens is increasing globally at an alarming rate with a need to discover novel and effective methods to cope infections due to these pathogens. Green nanoparticles have gained attention to be used as efficient therapeutic agents because of their safety and reliability. In the present study, we prepared zinc oxide nanoparticles (ZnO NPs) from aqueous leaf extract of Acacia arabica. The nanoparticles produced were characterized through UV-Visible spectroscopy, scanning electron microscopy, and X-ray diffraction. In vitro antibacterial susceptibility testing against foodborne pathogens was done by agar well diffusion, growth kinetics and broth microdilution assays. Effect of ZnO NPs on biofilm formation (both qualitatively and quantitatively) and exopolysaccharide (EPS) production was also determined. Antioxidant potential of green synthesized nanoparticles was detected by DPPH radical scavenging assay. The cytotoxicity studies of nanoparticles were also performed against HeLa cell lines. The results revealed that diameter of zones of inhibition against foodborne pathogens was found to be 16-30 nm, whereas the values of MIC and MBC ranged between 31.25-62.5 µg/ml. Growth kinetics revealed nanoparticles bactericidal potential after 3 hours incubation at 2 × MIC for E. coli while for S. aureus and S. enterica reached after 2 hours of incubation at 2 × MIC, 4 × MIC, and 8 × MIC. 32.5-71.0% inhibition was observed for biofilm formation. Almost 50.6-65.1% (wet weight) and 44.6-57.8% (dry weight) of EPS production was decreased after treatment with sub-inhibitory concentrations of nanoparticles. Radical scavenging potential of nanoparticles increased in a dose dependent manner and value ranged from 19.25 to 73.15%. Whereas cytotoxicity studies revealed non-toxic nature of nanoparticles at the concentrations tested. The present study suggests that green synthesized ZnO NPs can substitute chemical drugs against antibiotic resistant foodborne pathogens.

In vitro study of antimicrobial activity of some plant seeds against bacterial strains causing food poisoning diseases / Estudo in vitro da atividade antimicrobiana de algumas sementes de plantas contra cepas bacterianas que causam doenças de intoxicação alimentar

In this research, some plant seeds powder was evaluated to find their potential effect to rule diseases of food poisoning. Antimicrobial effect of five plant seeds was examined contra Bacillus cereus, Staphylococcus aureus, Escherichia coli, Klebsiella. pneumonia and Candida albicans by using well diffusion method. Antimicrobial activity studies revealed high potential activity of plant seeds powder of Nigella sativa L., cucurbita pepo, Sesamum radiatum, Trigonella foenum-graecum, Linum usitatissimum with variable efficiency contra tested microbial strains with concentration of 100 mg/ml, except Sesamum radiatum scored no effect. The T. foenum and N. sativa seed powder showed the largest inhibition zone (24-20 mm) contra K. pneumonia, followed by S. aureus (20-18 mm) and C. albicans (15mm) respectively. The five plant seeds powder exhibited bacteriostatic and bactericidal effects with MIC's 20 and MBC 40 mg/ml against K. pneumonia, and MIC's 40 and MBC 60 mg/ml against S. aureus. The results of this study indicated that plants seeds powder have promising antimicrobial activities and their potential applications in food process. It could be utilized as a natural medicinal alternative instead of chemical substance.

Nesta pesquisa, o pó de sementes de plantas foi avaliado para encontrar seu efeito potencial no controle de doenças de intoxicação alimentar. O efeito antimicrobiano de cinco sementes de plantas foi examinado contra Bacillus cereus, Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia e Candida albicans usando o método de difusão bem. Estudos de atividade antimicrobiana revelaram alto potencial de atividade de sementes de plantas em pó de Nigella sativa L., Cucurbita pepo, Sesamum radiatum, Trigonella foenum-graecum, Linum usitatissimum com eficiência variável contra cepas microbianas testadas com concentração de 100 mg / ml, exceto Sesamum radiatum com pontuação não efeito. O pó de sementes de T. foenum e N. sativa apresentou a maior zona de inibição (24-20 mm) contra K. pneumonia, seguido por S. aureus (20-18 mm) e C. albicans (15 mm), respectivamente. O pó de cinco sementes de plantas exibiu efeitos bacteriostáticos e bactericidas com MIC's 20 e MBC 40 mg / ml contra K. pneumonia, enquanto MIC's 40 e MBC 60 mg / ml contra S. aureus. Os resultados deste estudo indicaram que os pós de sementes de plantas apresentam promissoras atividades antimicrobianas e suas potenciais aplicações em processos alimentícios. Ele poderia ser utilizado como alternativa medicinal natural em vez de substância química.

Listeria monocytogenes Sublethal Injury and Viable-but-Nonculturable State Induced by Acidic Conditions and Disinfectants.

The dormancy continuum hypothesis states that in response to stress, cells enter different stages of dormancy ranging from unstressed living cells to cell death, in order to ensure their long-term survival under adverse conditions. Exposure of Listeria monocytogenes cells to sublethal stressors related to food processing may induce sublethal injury and the viable-but-nonculturable (VBNC) state. In this study, exposure to acetic acid (AA), hydrochloric acid (HCl), and two disinfectants, peracetic acid (PAA) and sodium hypochlorite (SH), at 20°C and 4°C was used to evaluate the potential induction of L. monocytogenes strain Scott A into different stages of dormancy. To differentiate the noninjured subpopulation from the total population, tryptic soy agar with 0.6% yeast extract (TSAYE), supplemented or not with 5% NaCl, was used. Sublethally injured and VBNC cells were detected by comparing plate counts obtained with fluorescence microscopy and by using combinations of carboxyfluorescein and propidium iodide (viable/dead cells). Induction of sublethal injury was more intense after PAA treatment. Two subpopulations were detected, with phenotypes of untreated cells and small colony variants (SCVs). SCVs appeared as smaller colonies of various sizes and were first observed after 5 min of exposure to 5 ppm PAA at 20°C. Increasing the stress intensity from 5 to 40 ppm PAA led to earlier detection of SCVs. L. monocytogenes remained culturable after exposure to 20 and 30 ppm PAA for 3 h. At 40 ppm, after 3 h of exposure, the whole population was considered nonculturable, while cells remained metabolically active. These results corroborate the induction of the VBNC state. IMPORTANCE Sublethally injured and VBNC cells may evade detection, resulting in underestimation of a food product's microbial load. Under favorable conditions, cells may regain their growth capacity and acquire new resistant characteristics, posing a major threat for public health. Induction of the VBNC state is crucial for foodborne pathogens, such as L. monocytogenes, the detection of which relies almost exclusively on the use of culture recovery techniques. In the present study, we confirmed that sublethal injury is an initial stage of dormancy in L. monocytogenes that is followed by the VBNC state. Our results showed that PAA induced SCVs (a phenomenon potentially triggered by external factors) and the VBNC state in L. monocytogenes, indicating that tests of lethality based only on culturability may provide false-positive results regarding the effectiveness of an inactivation treatment.

In vitro study of antimicrobial activity of some plant seeds against bacterial strains causing food poisoning diseases.

In this research, some plant seeds powder was evaluated to find their potential effect to rule diseases of food poisoning. Antimicrobial effect of five plant seeds was examined contra Bacillus cereus, Staphylococcus aureus, Escherichia coli, Klebsiella. pneumonia and Candida albicans by using well diffusion method. Antimicrobial activity studies revealed high potential activity of plant seeds powder of Nigella sativa L., cucurbita pepo, Sesamum radiatum, Trigonella foenum-graecum, Linum usitatissimum with variable efficiency contra tested microbial strains with concentration of 100 mg/ml, except Sesamum radiatum scored no effect. The T. foenum and N. sativa seed powder showed the largest inhibition zone (24-20 mm) contra K. pneumonia, followed by S. aureus (20-18 mm) and C. albicans (15mm) respectively. The five plant seeds powder exhibited bacteriostatic and bactericidal effects with MIC's 20 and MBC 40 mg/ml against K. pneumonia, and MIC's 40 and MBC 60 mg/ml against S. aureus. The results of this study indicated that plants seeds powder have promising antimicrobial activities and their potential applications in food process. It could be utilized as a natural medicinal alternative instead of chemical substance.

Responses of Escherichia coli and Listeria monocytogenes to ozone treatment on non-host tomato: Efficacy of intervention and evidence of induced acclimation.

Because of the continuous rise of foodborne illnesses caused by the consumption of raw fruits and vegetables, effective post-harvest anti-microbial strategies are necessary. The aim of this study was to evaluate the anti-microbial efficacy of ozone (O3) against two common causes of fresh produce contamination, the Gram-negative Escherichia coli O157:H7 and Gram-positive Listeria monocytogenes, and to relate its effects to potential mechanisms of xenobiosis by transcriptional network modeling. The study on non-host tomato environment correlated the dose × time aspects of xenobiosis by examining the correlation between bacterial survival in terms of log-reduction and defense responses at the level of gene expression. In E. coli, low (1 µg O3/g of fruit) and moderate (2 µg O3/g of fruit) doses caused insignificant reduction in survival, while high dose (3 µg/g of fruit) caused significant reduction in survival in a time-dependent manner. In L. monocytogenes, moderate dose caused significant reduction even with short-duration exposure. Distinct responses to O3 xenobiosis between E. coli and L. monocytogenes are likely related to differences in membrane and cytoplasmic structure and components. Transcriptome profiling by RNA-Seq showed that primary defenses in E. coli were attenuated after exposure to a low dose, while the responses at moderate dose were characterized by massive upregulation of pathogenesis and stress-related genes, which implied the activation of defense responses. More genes were downregulated during the first hour at high dose, with a large number of such genes getting significantly upregulated after 2 hr and 3 hr. This trend suggests that prolonged exposure led to potential adaptation. In contrast, massive downregulation of genes was observed in L. monocytogenes regardless of dose and exposure duration, implying a mechanism of defense distinct from that of E. coli. The nature of bacterial responses revealed by this study should guide the selection of xenobiotic agents for eliminating bacterial contamination on fresh produce without overlooking the potential risks of adaptation.

Impact of Phytochemicals on Viability and Cereulide Toxin Synthesis in Bacillus cereus Revealed by a Novel High-Throughput Method, Coupling an AlamarBlue-Based Assay with UPLC-MS/MS.

Due to its food-poisoning potential, Bacillus cereus has attracted the attention of the food industry. The cereulide-toxin-producing subgroup is of particular concern, as cereulide toxin is implicated in broadscale food-borne outbreaks and occasionally causes fatalities. The health risks associated with long-term cereulide exposure at low doses remain largely unexplored. Natural substances, such as plant-based secondary metabolites, are widely known for their effective antibacterial potential, which makes them promising as ingredients in food and also as a surrogate for antibiotics. In this work, we tested a range of structurally related phytochemicals, including benzene derivatives, monoterpenes, hydroxycinnamic acid derivatives and vitamins, for their inhibitory effects on the growth of B. cereus and the production of cereulide toxin. For this purpose, we developed a high-throughput, small-scale method which allowed us to analyze B. cereus survival and cereulide production simultaneously in one workflow by coupling an AlamarBlue-based viability assay with ultraperformance liquid chromatography-mass spectrometry (UPLC-MS/MS). This combinatory method allowed us to identify not only phytochemicals with high antibacterial potential, but also ones specifically eradicating cereulide biosynthesis already at very low concentrations, such as gingerol and curcumin.

HPLC-Analysis, Biological Activities and Characterization of Action Mode of Saudi Marrubium vulgare against Foodborne Diseases Bacteria.

The present study aims to evaluate the chemical composition, metabolites secondary and pharmacology activities of methanolic extract of Marrubium vulgare collected from King Saudi Arabia. Moreover, the primary mode of action of the tested extract was studied here for the first time against E. coli and L. monocytogenes. HPLC analysis shows that the major components in the tested extract are luteolin-7-O-d-glucoside, ferulic acid and premarrubiin. Obtained data demonstrated that the investigated extract was richer in phenol (26.8 ± 0.01 mg/GAE g) than in flavonoids (0.61 ± 0.05 mg EC/mL). In addition, the methanolic extract showed an important antioxidant capacity against the DPPH (IC50 = 35 ± 0.01 µg/mL) and ABTS (IC50 = 25 ± 0.2 µg/mL) radical scavenging and a strong inhibition of acetylcholinesterase enzyme with an IC50 value corresponding to 0.4 mg/mL. The antibacterial activity demonstrated that the evaluated extract had significant activity against both Gram-positive and Gram-negative bacteria. The effect of time on cell integrity on E. coli and L. monocytogenes determined by time-kill and bacteriolysis tests showed that the M. vulgare extract reduced the viability of both strains after 8 and 10 h and had a bacteriolytic effect against two different categories of bacteria, Gram-positive and negative, which are not of the same potency. Based on obtained data, it can be concluded that Saudi M. vulgare has a high pharmacological importance and can be used in preparation of food or drugs.

Assessing the efficiency of essential oil and active compounds/poly (lactic acid) microcapsules against common foodborne pathogens.

Essential oils' active compounds present great potential as a bactericidal agent in active packaging. The encapsulation in polymeric walls promotes their protection against external agents besides allowing controlled release. This work produced PLA capsules with three different active compounds, Cinnamomum cassia essential oil (CEO), eugenol (EEO), and linalool (LEO), by emulsion solvent evaporation method. Characterizations included SEM, Zeta potential, FTIR, TGA, and bactericidal activity against E. coli, S. aureus, L. monocytogenes, and Salmonella. The active compounds showed microbiological activity against all pathogens. CEO capsules showed superior colloidal stability. The active compounds' presence in all capsules was confirmed by FTIR analysis, with possible physical interaction between CEO, EEO, and the polymeric matrix, while LEO had a possible chemical interaction with PLA. TGA analysis showed a plasticizing effect of active compounds, and the loading efficiency was 39.7%, 50.7%, and 22.3% for CEO-PLA, EEO-PLA, and LEO-PLA, respectively. The capsules presented two release stages, sustaining activity against pathogens for up to 28 days, indicating a satisfactory internal morphology. This study presented methodology for encapsulation of antimicrobial compounds that can be suitable for active food packaging. CEO-PLA capsules regarding stability and antibacterial activity achieved the best results.