Listeria Monocytogenes In Foods Research Articles

Colorimetric aptasensor for Listeria monocytogenes detection using dual functional Fe3O4@MIL-100(Fe) with magnetic separation and oxidase-like activities in food samples.

A novel colorimetric aptasensor assay based on the excellent magnetic responsiveness and oxidase-like activity of Fe3O4@MIL-100(Fe) was developed. Fe3O4@MIL-100(Fe) absorbed with aptamer and blocked by BSA served as capture probe for selective isolation and enrichment of Listeria monocytogenesone of the most common and dangerous foodborne pathogenic bacteria. The aptamer absorbed on Fe3O4@MIL-100(Fe) was further used as signal probe that specifically binds with target bacteria conjugation of capture probe for colorimetric detection of Listeria monocytogenes, taking advantages of its oxidase-like activity. The linear range of the detection of Listeria monocytogenes was from 102 to 107CFUmL-1, with the limit of detection as low as 14CFUmL-1. The approach also showed good feasibility for detection of Listeria monocytogenes in milk and meat samples. The spiked recoveries were in the range 81-114% with relative standard deviations ranging from 1.28 to 5.19%. Thus, this work provides an efficient, convenient, and practical tool for selective isolation and colorimetric detection of Listeria monocytogenes in food.

A novel electrochemical biosensor based on SRCA-NEMA-G-quadruplex for sensitive detection of Listeria monocytogenes in food

Listeria monocytogenes (L. monocytogenes), as one of the most common foodborne pathogens, has caused many foodborne diseases, posing a major threat to food and public health safety. Therefore, a novel electrochemical biosensor was proposed based on the combination of saltatory rolling circle amplification (SRCA) and nicking enzyme mediated amplification (NEMA) for detecting Listeria monocytogenes. When L. monocytogenes was present, abundant double-stranded DNA (dsDNA) were produced by SRCA reaction. SRCA products could be specifically recognized and cleaved by Nb.BsmI. SRCA-NEMA was performed to generate abundant single-stranded DNA (ssDNA) with the action of Bst DNA polymerase and Nb.BsmI. The hydrosulfuryl-modified hairpin DNA (HS-hpDNA) was immobilized on the electrode surface and G-quadruplex was used as signaling molecule. The current signal increased with target DNA concentration and the ratio of the current could be calculated as the result. Subsequently, the detection linear range for L. monocytogenes genomic DNA was 5.4 × 100-5.4 × 107 fg/μL, with the detection limit of 2.13 fg/μL. In comparison with ISO 11290-1:2017 method, the relative sensitivity, relative specificity and relative accuracy of the developed method were 100 %, 97.8 % and 98 %, respectively. Overall, the developed method provides an outstanding platform for sensitive detection of L. monocytogenes in food.

Detection of Listeria monocytogenes in Food Using the Proofman-LMTIA Assay.

Microbial factors, including bacteria, viruses, and other pathogens, are significant contributors to foodborne illnesses, posing serious food safety risks due to their potential for rapid growth and contamination. Listeria monocytogenes is one of the most common types of foodborne bacteria that can cause serious foodborne diseases or even fatalities. In this study, a novel nucleic acid amplification method called Proofman-LMTIA was employed to detect Listeria monocytogenes contamination in food. This method combines proofreading enzyme-mediated probe cleavage with ladder-shape melting temperature isothermal amplification. A positive recombinant plasmid was used as a control to ensure the accuracy of the detection results, and primers and Proofman probes were specifically designed for the LMTIA. Genomic DNA was extracted, the reaction temperature was optimized, and the primers' specificity was verified using foodborne pathogens like Staphylococcus aureus, Escherichia coli O157:H7, and Salmonella. The sensitivity was assessed by testing serial dilutions of genomic DNA, and the method's applicability was confirmed by detecting artificially contaminated fresh pork. The established LMTIA method exhibited both high specificity and sensitivity. At the optimal reaction temperature of 63 °C, the primers specifically identified Listeria monocytogenes contamination in pork at a concentration of 8.0 ± 0.7 colony-forming units (CFUs) per 25 g. Furthermore, the Proofman-LMTIA method was applied to test Listeria monocytogenes DNA in 30 food samples purchased from a Chinese retail market, and reassuringly, all results indicated no contamination. Proofman-LMTIA can serve as a reliable and rapid method for detecting Listeria monocytogenes in food, contributing to public health by safeguarding consumers from foodborne illnesses, and strengthening food safety regulations.

Detection of Listeria monocytogenes in foods with a textile organic electrochemical transistor biosensor

Foods contaminated by pathogens are responsible for foodborne diseases which have socioeconomic impacts. Many approaches have been extensively investigated to obtain specific and sensitive methods to detect pathogens in food, but they are often not easy to perform and require trained personnel. This work aims to propose a textile organic electrochemical transistor-based (OECT) biosensor to detect L. monocytogenes in food samples. The analyses were performed with culture-based methods, Listeria Precis™ method, PCR, and our textile OECT biosensor which used poly(3,4-ethylenedioxythiophene) (PEDOT):polystyrene sulfonate (PSS) (PEDOT:PSS) for doping the organic channel. Atomic force microscopy (AFM) was used to obtain topographic maps of the gold gate. The electrochemical activity on gate electrodes was measured and related to the concentration of DNA extracted from samples and hybridized to the specific capture probe immobilized onto the gold surface of the gate. This assay reached a limit of detection of 1.05 ng/μL, corresponding to 0.56 pM of L. monocytogenes ATCC 7644, and allowed the specific and rapid detection of L. monocytogenes in the analyzed samples.Keypoints• Textile organic electrochemical transistors functionalized with a specific DNA probe• AFM topographic and surface potential maps of a functionalized gold gate surface• Comparison between the Listeria monocytogenes Precis™ method and an OECT biosensor

LISTERIA MONOCYTOGENES BACTERIUM IN THE AREA OF MOSTAR: OCCURRENCE IN VEGETABLES AND HEALTH RISKS

This research focuses on the bacterium Listeria monocytogenes and its occurrence in vegetables, specifically, tomatoes and peppers, and the risks this bacterium poses to health. The research included laboratory analysis of 16 samples of tomatoes and peppers, as well as survey research in the area of the City of Mostar. Based on the survey questionnaire, the respondents showed their knowledge about the occurrence of the bacteria Listeria monocytogenes in food and their general knowledge about listeriosis. Laboratory analysis consists of two parts. The first part refers to the laboratory analysis of the samples conducted in the Federal Agro-Mediterranean Institute laboratory in collaboration with its employees. The second part refers to an additional laboratory analysis conducted in the Veterinary Institute of Herzegovina–Neretva Canton laboratory in Mostar. This laboratory research aimed to establish whether the bacterium Listeria monocytogenes was present in the samples of vegetables examined in the analysis. All the vegetable samples were chosen randomly from four different locations in the area of Mostar. Also, the analysis included the examination of the washed and unwashed tomatoes and peppers. After conducting the laboratory research, it was established that the bacterium Listeria monocytogenes was not found in the samples used, which means all the examination results were negative.

Portable sensor based on magnetic separation and enzyme-mediated immune nanomaterials for point-of-care testing of Listeria monocytogenes in food

Listeria monocytogenes (L. monocytogenes), a typical foodborne pathogen, poses a serious threat to public health safety. This stimulates to develop a point-of-care testing (POCT) method to achieve rapid, sensitive detection of L. monocytogenes. In this study, polyethylene glycol (PEG) mediated ampicillin functionalized magnetic beads (Amp-PEG-MBs) was prepared successfully and it achieved high efficiency (>90%) and rapid (5 min) capture for L. monocytogenes at room temperature. The innovative combination of antibody (Ab), glucose oxidase (GOD) and graphene oxide (GO) prepared Ab@GO@GOD for the specific recognition of L. monocytogenes. Finally, Amp-PEG-MBs and Ab@GO@GOD were successfully assembled into Amp-PEG-MBs@L. monocytogenes-Ab@GO@GOD sandwich structure which could catalyze the glucose, and the final detection results were recorded by a blood glucose meter (BGM). Magnetic separation (MS) combined with enzyme-catalyzed sensor (MS-Ab@GO@GOD-BGM) was successfully established to achieve the detection of L. monocytogenes in artificially contaminated juice within 66 min with the limit of detection was 101 CFU/mL. This sensor has potential for other pathogens detection by modifying specific antibodies.

Essential Oils as Potential Tools to Control Listeria Monocytogenes in Foods

Foodborne diseases are indisputable risks to human health, as they are directly affected by the consumption of food and beverages exposed to spoiling and pathogenic microorganisms. A commonly confronted issue by the food industry is the use of synthetic additives to control microbial growth on food products. Alternatively, plant essential oils (EOs) are natural compounds with antimicrobial effects against pathogens in edible and drinkable products. Based on bacteriostatic and bactericidal activities, this review describes the antimicrobial effects of plant EOs on Listeria monocytogenes, also indicating their potential applicability in different food products. Conclusively, it is determined that the Gram-positive bacteria have more susceptibilities to the EOs. In addition, the antibacterial efficacy of the EOs reported in the literature varied according to several parameters, including the seasonal harvest of plants, well-settled methodologies for extraction of EOs, experimental conditions for testing the antibacterial effect on L. monocytogenes, and matrix effects considering several types of foodstuffs. This later represents the main challenge to be addressed in future research aiming at specific applications of EOs in food products.

Establishment of droplet digital PCR for quantitative detection of Listeria monocytogenes in food

Establishment of droplet digital PCR for quantitative detection of Listeria monocytogenes in food

Prevalence of Listeria monocytogenes in Foods of Animal Origin: Study from Assam, A North-Eastern State of India

Listeriosis is an important emerging bacterial food-borne zoonotic disease caused by Listeria monocytogenes. During the last two decades, the organism has been implicated in several food-borne disease outbreaks making it a serious public health hazard. The pathogenic strains of Listeria can cause severe illness in man after the ingestion of contaminated food products, especially the refrigerated foods of animal origin. In India, very few studies have been carried out in respect to the occurrence and incidence of L. monocytogenes. Assam, one of the eight states of Northeastern India, where approximately 79.0 percent of the total population are non-vegetarians. Chicken meat, pork, chevon and beef are exclusively taken as regular food items throughout the state. The present study describes about isolation, identification and molecular characterization of L.monocytogens from different foods of animal origin from Assam, India. A total of 750 different meat (chicken, chevon, pork and beef) and milk and their products (curd and paneer) samples were collected and analyzed for presence of Listeria. Isolation of L. monocytogenes was done from different food samples of animal origin by using selective enrichment method. PCR was employed for confirmation of the suspected cultures of Listeria targeting prsand16SrRNAgene. Upon confirmation, the isolates were further characterized based on 16S rRNA gene and phylogenetic analysis was performed. Of 750 samples, 48 (6.4%) samples were found positive. The highest rate of isolation of Listeria spp. was recorded in raw milk (8.95%) followed by curd (6.58%), chevon (5.36%), chicken (5.74%), pork (5.98%) and beef (3.75%). Molecular characterization of the isolates based on 16S rRNA gene of L.monocytogens isolated from foods of animal origin from Assam with that of other sequences reported from different parts of the world revealed that all the isolates of the present study are clustered along with other L.monocytogens isolates reported from different parts of the world, however, showing more closely related to isolates reported from China.

The Antimicrobial Potential of Hexane Oils and Polyphenols-Rich Extracts from Pistacia vera L.

Pistachio (Pistacia vera L.) nuts contain nutrients and phytochemicals which have been linked to several positive outcomes. The aim of this research was to examine the antimicrobial effect of natural raw and roasted unsalted polyphenols-rich pistachio extracts (NRRE and RURE) and hexane oil fractions. American Type Culture Collection (ATCC), food and clinical isolates of Gram-positive bacteria (Listeria monocytogenes and Staphylococcus aureus), Gram-negative bacteria (Pseudomonas aeruginosa, Escherichia coli and Enterococcus faecium) and yeasts (Candida albicans) were used. In addition, the influence of the extraction method was evaluated. Generally, NRRE extracts were richer in polyphenolic compounds compared with RURE extracts. NRRE extracted with n-hexane was the most effective on Listeria monocytogenes food isolates strains (MIC values between 0.25 and 2.0 mg mL−1). All extracts, except for RURE extracted with n-hexane, were active against Listeria monocytogenes ATCC 13932. Both hexane oil fractions were active against Listeria monocytogenes ATCC 13932 and Enterococcus faecium DSZM 17050. The oil obtained from natural pistachio was active against three food isolates of Listeria monocytogenes. In conclusion, the present study indicates an inhibitory effect of pistachio polyphenols against Listeria monocytogenes, one of the most serious pathogens causing foodborne disease.

An enhanced visual detection assay for Listeria monocytogenes in food based on isothermal amplified peroxidase-mimicking catalytic beacon

Listeria monocytogenes is a kind of foodborne pathogen, which can cause meningitis, septicemia, gastroenteritis, and abortion with a fatality rate of up to 30%. Rapid, sensitive, and convenient detection of L. monocytogenes in food is an important strategy for controlling contamination and infection. In this study, an enhanced visual detection assay for L. monocytogenes based on an isothermal amplified peroxidase-mimicking catalytic beacon was developed. When L. monocytogenes existed, G-quadruplex sequences were amplified together with targeted gene sequence by polymerase spiral reaction (PSR). G-quadruplex adequately formed DNAzyme with hemin to have an enhanced peroxidase-like bioactivity with help of Nb. BbvCI nicking endonuclease, which could display significant colorimetric signals for indicating positive results qualitatively. The sensitivity test results determined that our assay enabled the quantitative detection of L. monocytogenes ranging from 10 to 105 CFU mL−1, as well as had a detection limit of 3.1 CFU mL−1, which was lower than previous visual detection assays for L. monocytogenes. Besides, it was notable that this assay could detect L. monocytogenes with the concentration of 2.0 lg CFU/g in artificially contaminated pork samples within about 4 h, with the advantages of high sensitivity, simple operation, and good visual signal output. We believed the improved visual detection assay based on isothermal amplified peroxidase-mimicking catalytic beacon showed great potential for food safety analysis.

Dual recognition and highly sensitive detection of Listeria monocytogenes in food by fluorescence enhancement effect based on Fe3O4@ZIF-8-aptamer

A highly sensitive and selective foodborne pathogen detection system is essential to ensure food quality and public health. Therefore, in this study, a dual recognition and highly sensitive detection of Listeria monocytogenes by fluorescence enhancement strategy based on Fe3O4 @ZIF-8 have been developed. Aptamer absorbed on Fe3O4 @ZIF-8 were used for the specific capture of Listeria monocytogenes, and the conjugates of anti-Listeria monocytogenes antibody-biotin and streptavidin-FITC were used as signal amplification and fluorescence recognition probes binding with target bacteria. Simultaneously, the quantitative detection of Listeria monocytogenes was realized by monitoring the increase of FITC fluorescence signal due to hydrophobic environment. The linear range of the detection of pure culture was from 1.4 × 101 to 1.4 × 107 CFU/mL, with the detection limits as low as 0.88 CFU/mL and the coefficient of variation of each concentration no more than 2%. A good specificity of the detection system was also showed in the results, and the detection took about 70 min. Furthermore, the spiked samples of pork and milk were also tested by the detection system, and the recoveries ranged from 88.0% to 103.8%, with the coefficient of variation less than 12.8%. Taking advantages of sensitivity, rapidly and good selectivity, the proposed strategy in this study has great application potential in detection of foodborne pathogens in food.

Correlation of organic acid tolerance and genotypic characteristics of Listeria monocytogenes food and clinical isolates

A collection of Listeria monocytogenes isolates from various food products, food processing environments and clinical sources (n = 153) were evaluated for their tolerance to acetic, lactic and propionic acids. A large variation in tolerance was observed amongst isolates under mildly acidic conditions (pH 5.3) for acetic (5–20 mM undissociated acid) and propionic acid (2–10 mM undissociated acid) but there was less variation for lactic acid (3–6 mM undissociated acid). Analysis of the isolate genome sequences for a complement of genes previously shown to have a role in acid tolerance revealed that thiT, gadT2, gadD2 and gadD3 genes were linked to higher acetic acid tolerance (P < 0.05) while lisRK was linked to higher tolerance to propionic acid (P = 1 × 10−11). An absence of plasmid genes was also linked with isolates showing higher tolerance for all acids. Scoary GWAS analysis revealed that a total of 333, 207, and 333 genes were associated with acid tolerance for acetic, lactic, and propionic acid, respectively (P < 0.05). However, the p-value adjusted with Bonferroni's method for multiple comparisons did not reveal any significant associations. Isolates were grouped into clonal complexes (CC) using Multi Locus Sequence Typing (MLST) and MIC values for the three acids were determined for representative strains. One complex, CC18, showed significantly higher (P ≤ 0.05) acetic and propionic acid MIC values than other groups, whereas only CC7 type isolates revealed significantly higher (P ≤ 0.001) lactic acid MIC values. The results demonstrate that MLST typing could be linked to acid tolerance phenotypic traits which is important in predicting the behaviour of L. monocytogenes in food products.

Exogenous fatty acids affect membrane properties and cold adaptation of Listeria monocytogenes

Listeria monocytogenes is a food-borne pathogen that can grow at very low temperatures close to the freezing point of food and other matrices. Maintaining cytoplasmic membrane fluidity by changing its lipid composition is indispensable for growth at low temperatures. Its dominant adaptation is to shorten the fatty acid chain length and, in some strains, increase in addition the menaquinone content. To date, incorporation of exogenous fatty acid was not reported for Listeria monocytogenes. In this study, the membrane fluidity grown under low-temperature conditions was affected by exogenous fatty acids incorporated into the membrane phospholipids of the bacterium. Listeria monocytogenes incorporated exogenous fatty acids due to their availability irrespective of their melting points. Incorporation was demonstrated by supplementation of the growth medium with polysorbate 60, polysorbate 80, and food lipid extracts, resulting in a corresponding modification of the membrane fatty acid profile. Incorporated exogenous fatty acids had a clear impact on the fitness of the Listeria monocytogenes strains, which was demonstrated by analyses of the membrane fluidity, resistance to freeze-thaw stress, and growth rates. The fatty acid content of the growth medium or the food matrix affects the membrane fluidity and thus proliferation and persistence of Listeria monocytogenes in food under low-temperature conditions.

Whole-Genome Sequencing Characterization of Virulence Profiles of Listeria monocytogenes Food and Human Isolates and In Vitro Adhesion/Invasion Assessment

Listeria monocytogenes (Lm) is the causative agent of human listeriosis. Lm strains have different virulence potential. For this reason, we preliminarily characterised via Whole-Genome Sequencing (WGS) some Lm strains for their key genomic features and virulence-associated determinants, assigning the clonal complex (CC). Moreover, the ability of the same strains to adhere to and invade human colon carcinoma cell line Caco-2, evaluating the possible correspondence with their genetic virulence profile, was also assessed. The clinical strains typed belonged to clonal complex (CC)1, CC31, and CC101 and showed a very low invasiveness. The Lm strains isolated from food were assigned to CC1, CC7, CC9, and CC121. All CC1 carried the hypervirulence pathogenicity island LIPI-3 in addition to LIPI-1. Premature stop codons in the inlA gene were found only in Lm of food origin belonging to CC9 and CC121. The presence of LIPI2_inlII was observed in all the CCs except CC1. The CC7 strain, belonging to an epidemic cluster, also carried the internalin genes inlG and inlL and showed the highest level of invasion. In contrast, the human CC31 strain lacked the lapB and vip genes and presented the lowest level of invasiveness. In Lm, the genetic determinants of hypo- or hypervirulence are not necessarily predictive of a cell adhesion and/or invasion ability in vitro. Moreover, since listeriosis results from the interplay between host and virulence features of the pathogen, even hypovirulent clones are able to cause infection in immunocompromised people.

Comparative Evaluation of the SMARTCHECK® Listeria monocytogenes Detection Kit for GENECHECKER® UF-300 Real-Time PCR System for Select Foods: AOAC Performance Tested MethodSM 042101.

The candidate method, SMARTCHEK® Listeria monocytogenes Detection Kit, is designed for rapid detection of L. monocytogenes in select food matrixes, for use in conjunction with the Genesystems Rapi:chipTM and GENECHECKER®UF-300 real-time PCR system. The independent laboratory evaluation consisted of an inclusivity and exclusivity study, product consistency study, robustness study, stability study, and a matrix study. The paired matrix study tested stainless-steel environmental sponges, uncured ready-to-eat deli turkey, ready-to-eat deli ham, cooked shrimp, and fresh bagged spinach. The robustness study evaluated the method by changing three parameters. The accelerated stability and product consistency study was conducted at 8, 16, 24, 32, and 40 days. The candidate method was compared to the US Department of Agriculture Food Safety and Inspection Service Microbiology Laboratory Guidebook, 8.11 Isolation and Identification of Listeria monocytogenes from Red Meat, Poultry, Ready-to-Eat Siluriformes (Fish) and Egg Products, and Environmental Samples and to the US Food and Drug Administration Bacteriological Analytical Manual Chapter 10: Detection of Listeria monocytogenes in foods and Environmental Samples, and Enumeration of Listeria monocytogenes in Foods following a paired study design. All 50 L. monocytogenes isolates were detected in all three broths tested for inclusivity, while all 37 non-L. monocytogenes isolates were correctly excluded. In the matrix study, the candidate method showed no significant differences between confirmed candidate method results and reference method results for all food matrixes evaluated. The candidate method is an effective method for the qualitative detection of L. monocytogenes in select food matrixes. The SMARTCHECK Listeria monocytogenes Detection Kit assay allows for fast, reliable detection of L. monocytogenes with results obtained in approximately 35 min after 18-48 h pre-enrichment, depending on the matrix.

Impacts of Microbial Food Safety in China and Beyond.

Impacts of Microbial Food Safety in China and Beyond.

Prediction of population behavior of Listeria monocytogenes in food using machine learning and a microbial growth and survival database

In predictive microbiology, statistical models are employed to predict bacterial population behavior in food using environmental factors such as temperature, pH, and water activity. As the amount and complexity of data increase, handling all data with high-dimensional variables becomes a difficult task. We propose a data mining approach to predict bacterial behavior using a database of microbial responses to food environments. Listeria monocytogenes, which is one of pathogens, population growth and inactivation data under 1,007 environmental conditions, including five food categories (beef, culture medium, pork, seafood, and vegetables) and temperatures ranging from 0 to 25 °C, were obtained from the ComBase database (www.combase.cc). We used eXtreme gradient boosting tree, a machine learning algorithm, to predict bacterial population behavior from eight explanatory variables: ‘time’, ‘temperature’, ‘pH’, ‘water activity’, ‘initial cell counts’, ‘whether the viable count is initial cell number’, and two types of categories regarding food. The root mean square error of the observed and predicted values was approximately 1.0 log CFU regardless of food category, and this suggests the possibility of predicting viable bacterial counts in various foods. The data mining approach examined here will enable the prediction of bacterial population behavior in food by identifying hidden patterns within a large amount of data.

Optimization of the Growth of Pediococcus pentosaceus Strain 2397 in Inhibiting Pathogenic Listeria monocytogenes

Listeria monocytogenes (LM) is a pathogenic bacteria that can cause listeriosis in humans, generally transmitted through food. Various food preservatives have been used to prevent contamination from LM in food; one of them is bacteriocin produced by lactic acid bacteria. The purpose of the present study was to determine the optimum growth conditions for Pediococcus pentosaceus strain 2397 isolated from dadih in inhibiting LM in vitro assay. The supernatant’s antimicrobial activity obtained from Pediococcus pentosaceus strain 2397 against LM was determined using a well diffusion method. The results showed that the supernatants from strain R-55 could inhibit LM’s growth with various inhibition zones. The optimal growth conditions for Pediococcus pentosaceus strain 2397 to perform its antimicrobial activity against LM were at 72 h of incubation time, pH 6.3, and 2, 5% of starter concentration with an inhibition zone of 12, 3 mm.

Development of a fluorescence aptasensor for rapid and sensitive detection of Listeria monocytogenes in food

In this study, a simple fluorescence aptasensor was developed for rapid and sensitive detection of Listeria monocytogenes in food. The aptasensor was comprised of two parts. Aptamer-functionalized upconversion nanoparticles (UCNPs) recognized and adhered to the L. monocytogenes cells and provided strong fluorescent signals. Aptamer-functionalized magnetic nanoparticles (MNPs), which also recognized and adhered to the cells, were used to concentrate the aptamer-UCNP/L. monocytogenes/aptamer-MNP complex. The fluorescence intensity was measured and calibrated to a concentration series of L. monocytogenes. A low limit of detection of 8 cfu mL−1 was estimated from the range of 68 to 68 × 106 cfu mL−1. Compared with other methods currently available, the proposed method had wider detection range and higher sensitivity. Furthermore, the selectivity and functionality when used to detect L. monocytogenes in real food samples suggest it may be useful for practical applications.