RESUMEN
Foodborne diseases remain a worldwide concern, despite the advances made in sanitation, pathogen surveillance and food safety management systems. The methods routinely applied for detecting pathogens in foods are time consuming, labor intensive and usually require trained and qualified individuals. The objective of this review was to highlight the use of biosensors, with a focus on the electrochemical devices, as promising alternatives for detecting foodborne pathogens. These biosensors present high speed for obtaining results, with the possibility of evaluating foods in real time, at low cost, ease of use, in addition to being compact and portable. These aspects are considered advantageous and suitable for use in food safety management systems. This work also shows some limitations for the application of biosensors, and we present perspectives with the development and use of nanomaterials.
Asunto(s)
Técnicas Biosensibles , Técnicas Electroquímicas , Microbiología de Alimentos , Inocuidad de los Alimentos , Enfermedades Transmitidas por los Alimentos , Técnicas Biosensibles/instrumentación , Técnicas Biosensibles/métodos , Inocuidad de los Alimentos/métodos , Técnicas Electroquímicas/instrumentación , Técnicas Electroquímicas/métodos , Enfermedades Transmitidas por los Alimentos/microbiología , Enfermedades Transmitidas por los Alimentos/prevención & control , Humanos , Microbiología de Alimentos/métodos , Microbiología de Alimentos/instrumentación , Bacterias/aislamiento & purificación , Bacterias/clasificación , Bacterias/genéticaRESUMEN
Foodborne diseases caused by Salmonella enterica (S. enterica) and Staphylococcus aureus (S. aureus) significantly impact public health, underscoring the imperative for highly sensitive, rapid, and accurate detection technologies to ensure food safety and prevent human diseases. Nanomaterials hold great promise in the development of high-sensitivity transistor biosensors. In this work, field-effect transistor (FET) comprising high-purity carbon nanotubes (CNTs) were fabricated and modified with corresponding nucleic acid aptamers for the high-affinity and selective capture of S. enterica and S. aureus. The aptamer-functionalized CNT-FET biosensor demonstrated ultra-sensitive and rapid detection of these foodborne pathogens. Experimental results indicated that the biosensor could detect S. enterica at a limit of detection (LOD) as low as 1 CFU in PBS buffer, and S. aureus at an LOD of 1.2 CFUs, achieving single-cell level detection accuracy with exceptional specificity. The biosensor exhibited a rapid response time, completing single detections within 200 s. Even in the presence of interference from six complex food matrices, the biosensor maintained its ultra-sensitive (3.1 CFUs) and rapid response (within 200 s) characteristics for both pathogens. The developed aptamer-functionalized CNT-FET biosensor demonstrates a capability for low-cost, ultra-sensitive, label-free, and rapid detection of low-abundance S. enterica and S. aureus in both buffer solutions and complex environments. This innovation holds significant potential for applying this detection technology to on-site rapid testing scenarios, offering a promising solution to the pressing need for efficient and reliable pathogen monitoring in various settings.
Asunto(s)
Aptámeros de Nucleótidos , Técnicas Biosensibles , Límite de Detección , Nanotubos de Carbono , Salmonella enterica , Staphylococcus aureus , Transistores Electrónicos , Nanotubos de Carbono/química , Salmonella enterica/aislamiento & purificación , Staphylococcus aureus/aislamiento & purificación , Técnicas Biosensibles/instrumentación , Aptámeros de Nucleótidos/química , Humanos , Microbiología de Alimentos/instrumentación , Análisis de la Célula Individual/instrumentaciónRESUMEN
The detection of Salmonella in spices is challenging due to the presence of antibacterial components. In this study, we evaluated the use of an adsorbent beta zeolite in pre-enrichment media to improve the recovery of Salmonella from cinnamon bark and oregano leaves. Samples (25 g) were spiked with varying levels of S. Montevideo or S. Senftenberg. After 2 weeks of stabilization at RT, betazeolite was added to cinnamon and oregano samples prior to the addition of 225 mL or 475 mL of pre-enrichment media, respectively. Detection sensitivity and rate of the test method were compared to the FDA Bacteriological Analytical Manual (BAM) method which requires the use of 2.5 L pre-enrichment broth. While Salmonella could not be detected in the test method using the reduced volume of pre-enrichment media alone, the addition of beta zeolite resulted in a positivity rate of 62% and 72.6% for cinnamon bark and oregano leaves respectively (all spike levels and both serovars combined). Furthermore, while there were differences in the LOD50 compared to the BAM method, there was no significant difference in the minimum level of detection between the betazeolite and the BAM methods. Our results demonstrate that the use of betazeolite in the pre-enrichment media offers a method with reduced media volumes without compromising on the sensitivity or efficiency of Salmonella detection in cinnamon bark and oregano leaves.
Asunto(s)
Cinnamomum zeylanicum/microbiología , Microbiología de Alimentos/métodos , Origanum/microbiología , Salmonella/crecimiento & desarrollo , Especias/microbiología , Zeolitas/química , Adsorción , Técnicas Bacteriológicas , Medios de Cultivo/química , Contaminación de Alimentos/análisis , Microbiología de Alimentos/instrumentación , Corteza de la Planta/microbiología , Hojas de la Planta/microbiología , Salmonella/aislamiento & purificación , Sensibilidad y EspecificidadRESUMEN
Consumer awareness and distaste towards both bacterial and chemical contaminations on food items have been increasing in recent years. Non-thermal plasma (NTP) is a cutting-edge technology which has been shown to effectively inactivate bacteria on the treated foods. Although the general NTP with a single plasma jet is appropriate for the continuous operation process, it suffers limitations due to its smaller scanning area. Here, a novel NTP device with a double rotary nozzle jet system was utilized, which could treat an area instead of a point. The shell eggs inoculated with Salmonella enterica serotype Enteritidis (SE) were placed on a moving platform under the double rotary nozzle jet system. The efficacy of the NTP treatment on microbial decontamination was evaluated by testing a total of 26 combinations of operating parameters consisting of various plasma power (150, 180, 210 W), argon flow rate (10, 15, 20 slm), repetition of the moving platform (4, 6, 8 times), and speed of the moving platform (5, 10 mm/s). Although significantly higher SE reduction (p < 0.05) was achieved with higher power, more repetitions, larger argon flow rates, and lower speed of the platform, these parameters induced significant alterations in the sensory properties of the treated eggs. By comprehensively considering the bacterial reductions, egg quality, and sensory properties, NTP treatment with combination T (180 W-15 slm-6 times-10 mm/s) was determined to be the optimal parameter, which achieved >4 log CFU/egg of SE reduction and significantly better sensory properties than commercially washed eggs (p < 0.05). Additionally, SEM analysis revealed that NTP treatment with combination T resulted in less damage to egg cuticles compared to commercially washed eggs. This novel NTP device offers an efficient antibacterial activity under shorter exposure time (30 s), smaller argon flow rate (15 slm), and lower power (180 W) without adversely affecting the overall quality of the treated eggs. Therefore, this NTP device equipped with the double rotary jet system possesses a potential solution for future industrial applications.
Asunto(s)
Desinfección , Cáscara de Huevo , Microbiología de Alimentos , Gases em Plasma , Salmonella enteritidis , Animales , Pollos , Recuento de Colonia Microbiana , Desinfección/instrumentación , Desinfección/métodos , Cáscara de Huevo/microbiología , Huevos/microbiología , Microbiología de Alimentos/instrumentación , Microbiología de Alimentos/métodos , Gases em Plasma/farmacología , Salmonella enteritidis/efectos de los fármacosRESUMEN
Yersiniosis - the 4th most commonly reported zoonosis in the European Union - is caused by the consumption of food contaminated with the bacterium Yersinia enterocolitica. The number of human cases and contaminated food samples is probably underestimated since conventional molecular methods currently proposed for Yersinia enterocolitica detection proved to have several limitations. Critical issues associated with the detection of Yersinia enterocolitica in meat and/or meat product has already been investigated, whereas data on the possible limits of the molecular methods for Yersinia enterocolitica detection in vegetables are still lacking. According to ISO method (ISO 18867:2015), real-time polymerase chain reaction (rtPCR) should be adopted for Yersinia enterocolitica detection, even if it proved to be affected by some biases. Recently, Droplet Digital PCR (ddPCR) has been introduced as a useful tool to detect and quantify different pathogenic bacteria in complex food matrices. However, its potential application for Yersinia enterocolitica detection in vegetables has never been investigated before. In the present study two molecular platforms (rtPCR and ddPCR) were used to evaluate the pathogen's behaviour in experimentally contaminated leafy greens (Lactuca sativa L.) and to assess the rate of detection achievable after the incubation for eleven days at different temperatures. By comparing, noticeable differences emerged between the two technical approaches: only ddPCR allowed the detection of the pathogen in leafy greens when contaminated at low levels. Moreover, results of the present work highlighted the importance of length and temperature of incubation on the survival and/or the growth of Yersinia enterocolitica in vegetables: at 18 and 25 °C the concentration of the pathogen considerably decreases along incubation. Based on data, the use of rtPCR leads to an underestimation of the true prevalence of pathogenic Y. enterocolitica in vegetables, while temperature and time currently proposed for Y. enterocolitica (25 °C for 24 h), allow optimizing detection. To conclude, ddPCR may be undoubtedly proposed as a reliable alternative strategy for the quick detection of the pathogen in food samples.
Asunto(s)
Microbiología de Alimentos , Técnicas de Amplificación de Ácido Nucleico , Reacción en Cadena en Tiempo Real de la Polimerasa , Verduras , Yersiniosis , Yersinia enterocolitica , Microbiología de Alimentos/instrumentación , Microbiología de Alimentos/métodos , Técnicas de Amplificación de Ácido Nucleico/normas , Reacción en Cadena en Tiempo Real de la Polimerasa/normas , Verduras/microbiología , Yersinia enterocolitica/genéticaRESUMEN
Genomic diversity of Listeria monocytogenes isolates from the deboning and slicing areas of three dry-cured ham processing plants was analysed. L. monocytogenes was detected in 58 out of 491 samples from the environment and equipment surfaces, all from the deboning area, with differences in prevalence among facilities. The most frequent PCR-serogroup was IIa (74.1%) followed by IIb and IIc, and only one isolate was serogroup IVb. Twenty different pulsotypes and 11 sequence types (STs) grouped into 10 clonal complexes (CCs) were determined. ST121 (CC121) and ST9 (CC9) were the most abundant. Premature stop codons (PMSC6 and PMSC19) associated with attenuated virulence were found in the inlA sequence in 7 out of 12 selected strains. CC121 strains were strong biofilm formers and some harboured the transposon Tn6188, related with increased tolerance to quaternary ammonium compounds. L. monocytogenes clones considered hypovirulent resulted predominant in the deboning areas. The clonal structure and potential virulence of the isolates could help to establish adequate control measures and cleaning protocols for the comprehensive elimination of the pathogen in dry-cured ham processing environment.
Asunto(s)
Equipos y Suministros/microbiología , Variación Genética , Listeria monocytogenes/genética , Listeria monocytogenes/aislamiento & purificación , Productos de la Carne/microbiología , Animales , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Técnicas de Tipificación Bacteriana , Biopelículas , Contaminación de Equipos/estadística & datos numéricos , Manipulación de Alimentos/instrumentación , Microbiología de Alimentos/instrumentación , Genómica , Listeria monocytogenes/clasificación , Listeria monocytogenes/fisiología , Carne de Cerdo/microbiología , PorcinosRESUMEN
Spices and herbs are widely used in almost all types of food preparation and their microbial contamination may cause spoilage and pose public health risk. Thus, the aim of this study was to assess the effect of packaging, source and a food safety management system (FSMS) on the microbiological quality of spices and dried herbs in a developing country, like Lebanon. For this, a total of 96 composite samples of thirteen most commonly consumed types of spices and dried herbs were collected twice at three-month interval. Each type was purchased in 5 common brands from 4 categories: packaged in companies with FSMS, packaged in companies without FSMS, packaged imported, and unpackaged. Total aerobic mesophilic bacteria (TAMB), sulfite reducing anaerobic bacteria, C. perfringens, coliforms, E. coli, yeasts and molds were found in 89%, 43%, 18%, 15%, 1% and 54% of the samples, respectively. All samples were negative for Salmonella. One per cent, 4%, 6%, 1% and 7% of the samples had unacceptable levels of TAMB, coliforms, sulfite reducing anaerobic bacteria, E. coli, yeasts and molds, respectively. Among the four categories, imported samples had the lowest microbiological load, followed by locally packaged in companies with FSMS, then locally packaged in companies without FSMS and the highest microbiological load was for the unpackaged spices and dried herbs. This study highlighted the importance of storage conditions, good hygienic practices, process controls and FSMSs in the spices and dried herbs sector.
Asunto(s)
Microbiología de Alimentos , Embalaje de Alimentos , Administración de la Seguridad , Especias , Fenómenos Fisiológicos Bacterianos , Países en Desarrollo , Microbiología de Alimentos/instrumentación , Microbiología de Alimentos/métodos , Embalaje de Alimentos/normas , Hongos/fisiología , Administración de la Seguridad/métodos , Especias/microbiologíaRESUMEN
Rapid detection of pathogenic bacteria particularly in food samples demands efficient separation and enrichment strategies. Here, hydrophilic temperature-responsive boronate affinity magnetic nanocomposites were established for selective enrichment of bacteria. The thermo-responsive polymer brushes were developed by surface-initiated atom transfer radical polymerization of N-isopropylacrylamide (NIPAm) and allyl glycidyl ether (AGE), followed by a reaction of epoxy groups, and incorporation of fluorophenylboronic acid. The physical and chemical characteristics of the magnetic nanocomposites were analyzed systematically. After optimization, S. aureus and Salmonella spp. showed high binding capacities of 32.14 × 106 CFU/mg and 50.98 × 106 CFU/mg in 0.01 M PBS (pH 7.4) without bacteria death. Bacterial bindings can be controlled by altering temperature and the application of competing monosaccharides. The nanocomposite was then utilized to enrich S. aureus and Salmonella spp. from the spiked tap water, 25% milk, and turbot extraction samples followed by multiplex polymerase chain reaction (mPCR), which resulted in high bacteria enrichment, and demonstrated great potential in separation of bacteria from food samples.
Asunto(s)
Bacterias/aislamiento & purificación , Microbiología de Alimentos/instrumentación , Microbiología de Alimentos/métodos , Nanocompuestos/química , Acrilamidas/química , Animales , Bacterias/metabolismo , Técnicas Bacteriológicas/instrumentación , Técnicas Bacteriológicas/métodos , Concentración de Iones de Hidrógeno , Interacciones Hidrofóbicas e Hidrofílicas , Fenómenos Magnéticos , Leche/microbiología , Polimerizacion , Polímeros/química , Salmonella/aislamiento & purificación , Salmonella/metabolismo , Staphylococcus aureus/metabolismo , Temperatura , Microbiología del AguaRESUMEN
The production of volatile compounds in naturally fermented green table olives from Manzanilla cultivar was investigated. A total of 62 volatile compounds were detected after 24 weeks of fermentation. To clarify the contribution of yeasts to the formation of these compounds, such microorganisms were isolated from the corresponding fermenting brines. Five major yeast strains were identified: Nakazawaea molendinolei NC168.1, Zygotorulaspora mrakii NC168.2, Pichia manshurica NC168.3, Candida adriatica NC168.4, and Candida boidinii NC168.5. When these yeasts were grown as pure cultures in an olive-derived culture medium, for 7 days at 25 °C, the number of volatiles produced ranged from 22 (P. manshurica NC168.3) to 60 (C. adriatica NC168.4). Contribution of each yeast strain to the qualitative volatile profile of fermenting brines ranged from 19% (P. manshurica NC168.3) to 48% (Z. mrakii NC168.2 and C. adriatica NC168.4). It was concluded that C. adriatica NC168.4 presented the best aromatic profile, being a solid candidate to be part of a novel starter culture to enhance the organoleptic properties of naturally fermented green table olives.
Asunto(s)
Microbiología de Alimentos , Olea/microbiología , Compuestos Orgánicos Volátiles/metabolismo , Levaduras/metabolismo , Medios de Cultivo/química , Medios de Cultivo/metabolismo , Fermentación , Manipulación de Alimentos , Microbiología de Alimentos/instrumentación , Frutas/metabolismo , Frutas/microbiología , Olea/metabolismo , Sales (Química)/química , Sales (Química)/metabolismo , Compuestos Orgánicos Volátiles/química , Levaduras/clasificación , Levaduras/genética , Levaduras/aislamiento & purificaciónRESUMEN
Enumeration and isolation of Streptococcus salivarius subsp. thermophilus from cheese is challenging, due to the relatively high number of species it may host. We describe medium SPY9.3 for the cultivation of S. salivarius subsp. thermophilus from cheese. The medium and related incubation conditions (SPY) was compared with 2 other protocols, M17 and ST: sensitivity was assessed by parallel cultivation of 55 strains of S. salivarius subsp. thermophilus, and selectivity by (i) parallel cultivation of 60 strains belonging to 20 different non-target species and sub-species and (ii) isolating bacteria from 3 raw-milk cheeses. Colony counts were similar on SPY9.3 and M17 (mean difference 0.07 log(cfu/mL), p > 0.001) and significantly higher on ST than on M17 and SPY9.3 (mean differences 0.42 and 0.48 log(cfu/mL), respectively, p < 0.001). SPY was more specific than ST and M17, with respectively 20%, 40%, and 50% of the investigated non-target species able to grow. S. salivarius subsp. thermophilus, Enterococcus spp., and Staphylococcus aureus were indistinguishable using all 3 protocols. Only SPY avoided growth of Lactobacillus delbrueckii subsp. lactis. Finally, ST and SPY displayed higher recoveries of S. salivarius subsp. thermophilus colonies from cheese than M17 (5.6, 5.5, and 3.0 adjusted log(cfu/mL), respectively) and the lowest proportion of non-specific isolates. The protocol described here and based on SPY9.3 presents a promising alternative to existing protocols for the enumeration and isolation of S salivarius subsp. thermophilus from cheese or other complex fermented products.
Asunto(s)
Queso/microbiología , Medios de Cultivo/metabolismo , Microbiología de Alimentos/métodos , Streptococcus thermophilus/crecimiento & desarrollo , Streptococcus thermophilus/metabolismo , Animales , Bovinos , Recuento de Colonia Microbiana , Medios de Cultivo/química , Microbiología de Alimentos/instrumentación , Leche/microbiología , Streptococcus thermophilus/genéticaRESUMEN
In-house treatment strategy for fresh produce decontamination has not been emphasized as much as industrial washing. The most common treatment for fresh produce decontamination and cleaning at home and other point-of-use places such as cafeteria is rinsing and/or soaking in a sink. In this study, an appliance utilizing UV and agitated water to decontaminate fresh produce was developed and its effectiveness was investigated in an aim to identify optimum processing parameters. Grape tomato and spinach representing two different surface smoothness were dip-inoculated in a four-strain Salmonella cocktail to reach a final population of 5-8 log CFU/g and air-dried. The produce samples were then washed in 1 gallon tap water under varying conditions, water agitation speed (0-190 RPM), sample size (50-400 g), UV intensity (0-30 mW/cm2) and treatment time (2, 5 and 10 min). In general, increasing the agitation speed and UV intensity enhanced Salmonella inactivation for both grape tomato and spinach. Sample size significantly affected the UV inactivation of Salmonella on grape tomato, but not on spinach. The effect of extending treatment time from 2 to 10 min was insignificant for almost all the UV treatments and the controls. The effect of UV intensity and treatment time on inactivation of Salmonella on spot-inoculated grape tomato and spinach was also determined. The most severe treatment used in this study, 30 mW/cm2 UV for 10 min, resulted in >4 log reductions of Salmonella dip- or spot-inoculated on grape tomato (200 g sample size and 190 RPM agitation speed) and 3.5 log reductions of Salmonella dip- or spot-inoculated on spinach (100 g sample size and 110 RPM agitation speed). We foresee that the UV appliance developed and evaluated in this study could be further fine-tuned and optimized to eventually construct a point-of-use UV appliance that can be used at home, cafeteria, restaurants, and hospitals for fresh produce decontamination and cleaning. The UV appliance could be an inexpensive and effective tool to improve fresh produce safety.
Asunto(s)
Descontaminación/instrumentación , Descontaminación/métodos , Escherichia coli O157/efectos de la radiación , Microbiología de Alimentos/instrumentación , Microbiología de Alimentos/métodos , Rayos Ultravioleta , Recuento de Colonia Microbiana , Descontaminación/normas , Solanum lycopersicum/microbiología , Salmonella/efectos de la radiación , Spinacia oleracea/microbiología , AguaRESUMEN
Here we present an innovative label-free immunochromatographic strip (ICTS) sensor, in which salt-induced aggregated gold nanoparticles (SIA-AuNPs) act as the signal probe, allowing in 14 min the identification and sensitive quantification of Salmonella as model targets. It has been evidenced that SIA-AuNPs could be absorbed on the surface of bacteria based on van der Waals forces. The SIA-AuNPs@Salmonella complex was captured by anti-Salmonella polyclonal antibody deposited on the test zone. With the label-free ICTS sensor, we successfully detected Salmonella in a concentration range of 103-108 CFU/mL and a visual detection limit of 1 × 103 CFU/mL. The band of test zone could be distinguished at a concentration of 103 CFU/mL by naked eye, which is 100-fold lower than the cationic AuNPs based method. The strip sensor was further validated with real samples including cabbage and drinking water with excellent precision and showed to provide excellent recovery.
Asunto(s)
Cromatografía de Afinidad/métodos , Microbiología de Alimentos/métodos , Nanopartículas del Metal/química , Salmonella , Anticuerpos/inmunología , Brassica/microbiología , Cromatografía de Afinidad/instrumentación , Recuento de Colonia Microbiana , Microbiología de Alimentos/instrumentación , Oro/química , Límite de Detección , Salmonella/inmunologíaRESUMEN
Carbon quantum dots (CQDs) prepared by a green one-step approach was used for sensitive and selective assay of Escherichia coli O157: H7 (E. coli). CQDs was synthesized from orange peel as a carbon source via a microwave-assisted method. The CQDs displayed strong green fluorescence under excitation wavelength of 420 nm. A fluorescent probe (CQDs-MNPs) for E. coli was fabricated based on CQDs labeled with aptamer (aptamer-CQDs) and magnetic nanoparticles labeled with complementary DNA (cDNA-MNPs). Fluorescent intensity of the CQDs-MNPs was decreased with addition of E. coli. The linearity between fluorescent intensity and E. coli concentration was used for developing a fluorescent method with detecting range of 500-106 CFU/mL and detection limit of 487 CFU/mL. Milk samples contaminated by E. coli were analyzed by this method, and the results agreed with that achieved by plate-counting methods. This fluorescent probe exhibits great potential in guaranteeing food quality and safety.
Asunto(s)
Carbono/química , Citrus sinensis/química , Escherichia coli , Microbiología de Alimentos/métodos , Leche/microbiología , Puntos Cuánticos/química , Animales , Fluorescencia , Colorantes Fluorescentes/química , Microbiología de Alimentos/instrumentación , Tecnología Química Verde , Límite de Detección , Nanopartículas/químicaRESUMEN
Foodborne pathogen contamination has become a severe threat to human health. Traditional methods for foodborne pathogen detection have several disadvantages, including long detection time, low sensitivity, and low selectivity. The emergence of multiple excellent nanomaterials enables the construction of novel biosensors for foodborne pathogen detection. Based on the outstanding properties of nanomaterials, the novel biosensors possess the advantages of sensitivity, specificity, rapidity, accuracy, and simplicity. The present review comprehensively summarizes the advanced biosensors, including electrochemical, colorimetric, fluorescent, and surface enhanced Raman scattering biosensors for sensing key foodborne pathogens in recent decades. Furthermore, several issues are identified for further exploration, and possible directions for the development of biosensors are discussed.
Asunto(s)
Técnicas Biosensibles/instrumentación , Microbiología de Alimentos/instrumentación , Nanoestructuras , Bacterias/aislamiento & purificación , Técnicas Biosensibles/métodos , Contaminación de Alimentos/análisis , Microbiología de Alimentos/métodosRESUMEN
D-enantiomers of amino acids (D-AAs) are only present in low amounts in nature, frequently at trace levels, and for this reason, their biological function was undervalued for a long time. In the past 25 years, the improvements in analytical methods, such as gas chromatography, HPLC, and capillary electrophoresis, allowed to detect D-AAs in foodstuffs and biological samples and to attribute them specific biological functions in mammals. These methods are time-consuming, expensive, and not suitable for online application; however, life science investigations and industrial applications require rapid and selective determination of D-AAs, as only biosensors can offer. In the present review, we provide a status update concerning biosensors for detecting and quantifying D-AAs and their applications for safety and quality of foods, human health, and neurological research. The review reports the main challenges in the field, such as selectivity, in order to distinguish the different D-AAs present in a solution, the simultaneous assay of both L- and D-AAs, the production of implantable devices, and surface-scanning biosensors. These innovative tools will push future research aimed at investigating the neurological role of D-AAs, a vibrant field that is growing at an accelerating pace.
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Aminoácidos/análisis , Técnicas Biosensibles/instrumentación , Técnicas Biosensibles/métodos , Microbiología de Alimentos/instrumentación , Microbiología de Alimentos/métodos , Animales , HumanosRESUMEN
Herein, a label-free and dual-readout immunochromatographic test strip (ITS) for the sensitive detection of Escherichia coli (E. coli) O157:H7 by taking advantages of the strong capture ability of Fe3O4@CuS nanostructures (NSs) towards bacteria and their ultrahigh photothermal effects (PTEs) was reported. Especially, without the customarily antibody (Ab)-labeled probe, Fe3O4@CuS NSs could be adsorbed onto the surfaces of bacteria to form Fe3O4@CuS-bacteria conjugates and then trapped by immobilized Abs on the test line (T-line), forming a characteristic yellow band. After direct immunoreactions, the PTEs of Fe3O4@CuS NSs endowed T-line to be irradiated by an 808 nm infrared light, obtaining satisfactory sensitivity and accuracy. Under optimal conditions, E. coli O157:H7, as low as 103 and 102 CFU/mL, could be monitored in colorimetric and photothermal modes. Additionally, E. coli O157:H7 was successfully detected in beef, chicken, milk and honey samples by this proposed platform with a recovery of 80-120%.
Asunto(s)
Cromatografía de Afinidad/métodos , Cobre/química , Escherichia coli O157/aislamiento & purificación , Compuestos Férricos/química , Microbiología de Alimentos/métodos , Animales , Anticuerpos Monoclonales/inmunología , Bovinos , Pollos/microbiología , Cromatografía de Afinidad/instrumentación , Escherichia coli O157/inmunología , Microbiología de Alimentos/instrumentación , Miel/microbiología , Límite de Detección , Leche/microbiología , Tiras Reactivas/química , Carne Roja/microbiologíaRESUMEN
BACKGROUND: Species belonging to the genus Aspergillus have been used in traditional Japanese fermented foods. Aspergillus sojae is a species responsible for strong proteolytic activity. Freeze-drying treatments followed by physical disruption enables the pulverization of the mycelia of A. sojae RIB 1045 grown in whey protein-base solid media. Intracellular proteases were extracted using this protocol to compare extracellular protease activity in terms of the reaction's pH dependence in the presence or absence of inhibitors. RESULT: With different sensitivities to inhibitors, intracellular and extracellular proteases showed the strongest activity under acidic conditions, which were considered suitable for cheese application. The raw culture product (CP) and its freeze-dried product (FDP) were mixed with cheese curds, prepared according to Gouda-type cheese-making methods, and were allowed to ripen for 3 months. Chemical analysis of the products showed 13.3% water-soluble nitrogen (WSN) in the control, which had received noncultured media, whereas 20.0% and 21.1% WSN was found in the CP and FDP experimental cheeses, respectively. Although these adjuncts significantly increased WSN, an insignificant difference was found between CP and FDP. Free fatty acids in all experimental cheeses were similar, showing that CP and FDP caused no rancid defects. CONCLUSION: The introduction of freeze-drying treatments accompanied by cell disruption resulted in a negligible effect in terms of WSN. However, the application of A. sojae can be beneficial when it comes to increasing the level of WSN compared with A. oryzae, as shown in our previous study. © 2020 Society of Chemical Industry.
Asunto(s)
Aspergillus/crecimiento & desarrollo , Queso/microbiología , Medios de Cultivo/química , Microbiología de Alimentos/métodos , Animales , Aspergillus/química , Aspergillus/metabolismo , Bovinos , Queso/análisis , Medios de Cultivo/metabolismo , Fermentación , Microbiología de Alimentos/instrumentación , Liofilización , Leche/química , Leche/microbiología , Polvos/química , Polvos/metabolismoRESUMEN
Microfluidic labchips have achieved much advancement in the molecular diagnosis of foodborne pathogens. Whereas difficulties in the flow control during the transportation of liquid fluids can occur and should be overcome. Manipulations of reaction temperature and the complex procedures from sample pre-treatment to analysis in a single chip device are major obstacles for the on-site application. Thus, the efficient temperature control of samples without any flow of reaction fluids in microfluidic channels of plastic chip and the simplest protocol omitting post-enrichment processing steps may overcome these limitations represented by the stability and the complexity, respectively. This study aims to develop a novel type of labchip and thermocycler specialized for the gene amplification in microfluidic channels and to evaluate the detectability by sensing the minimum recoverable level of Cronobacter in powdered infant formula (PIF). We developed a thermocycling device accelerating reactions through dual heating-blocks optimized to control temperatures of samples in microfluidic-channels by direct contact with labchip sequentially and repetitively. The structural design of microfluidic channels was to eliminate interference factors associated with the optical detection of fluorescent signals (without distortion due to air bubbles in the reaction chamber). To improve the applicability, a portable device and simplified operation to allow direct loading of samples in the chip without post-enrichment procedures were also adopted. Detection performance was evaluated by a sensitivity/specificity tests using 50 isolates of Cronobacter. Cross-reactivity tests for non-Cronobacter organisms and gDNA [human, raw materials of PIF (cow, soybean)] showed that there was no interference-factor causing false-positive results. In terms of the applied research conducted by using PIF, the enrichment of samples without broth medium (distilled water) displayed outstanding performance and 12 h of incubation facilitated detecting target at concentration as low as 1 CFU/300 g PIF (as initial contamination level) without post-enrichment treatment. Validation of the operation conditions using 30 commercial PIF products was also consistent. The present study presents a novel approach of microfluidic technology with perspective to not only the performance and the practicability [easy-to-implement protocol, portable materials, cost-effectiveness (the use of a miniaturized plastic chip requires a minimum level of materials)] for on-site diagnosis.
Asunto(s)
Cronobacter/aislamiento & purificación , Microbiología de Alimentos/instrumentación , Microbiología de Alimentos/métodos , Fórmulas Infantiles/microbiología , Dispositivos Laboratorio en un Chip/normas , Animales , Cronobacter sakazakii/genética , Medios de Cultivo/análisis , Contaminación de Alimentos/análisis , Humanos , Lactante , Sensibilidad y Especificidad , TemperaturaRESUMEN
The objective of the present study was to assess the potential synergistic effect between supercritical carbon dioxide (SC-CO2) and fresh culinary herbs (Coriandrum sativum and Rosmarinus officinalis) on the microbial inactivation of raw chicken meat. The microbiological inactivation was performed on Escherichia coli and natural flora (total mesophilic bacteria, yeasts, and molds). High pressure treatments were carried out at 40°C, 80 or 140 bar from 15 to 45 min. Microbial inactivation had a strong dependence on treatment time, achieving 1.4 log CFU/g reduction of E. coli after 15 min, and up to 5 log after 45 min, while a pressure increase from 80 up to 140 bar was not significant on the microbial inactivation. Mesophilic microorganisms were strongly reduced (>2.6 log CFU/g) after 45 min, and yeasts and molds were below the detection limits of the technique (<100 CFU/g) in most cases. The combination of fresh herbs together with SC-CO2 treatment did not significantly increase the inactivation of either E. coli or natural flora, which was similar to the SC-CO2 alone. The synergistic effect was obtained on the inactivation of E. coli using a proper concentration of coriander essential oil (EO) (0.5% v/w), while rosemary EO did not show a significant effect. Color analysis after the treatment showed an increment of lightness (L*), and a decrease of redness (a*) on the surface of the sample, making the product visually similar to cooked meat. Texture analysis demonstrated the modification of the texture parameters as a function of the process pressure making the meat more similar to the cooked one.
Asunto(s)
Dióxido de Carbono/análisis , Microbiología de Alimentos/métodos , Conservación de Alimentos/métodos , Carne/microbiología , Viabilidad Microbiana , Aceites Volátiles/administración & dosificación , Animales , Pollos , Escherichia coli/fisiología , Microbiología de Alimentos/instrumentación , Conservación de Alimentos/instrumentación , Hongos/fisiología , Aceites de Plantas/administración & dosificación , Presión , Levaduras/fisiologíaRESUMEN
Food poisoning is still the first cause of hospitalization worldwide and the most common microbial agent, Campylobacter jejuni, is the most commonly reported gastrointestinal disease in humans in the EU (European Union) as is reported by the European Union One Health 2018 Zoonoses Report styled by the EFSA (European Food Safety Authority) and ECDC (European Center for Disease Prevention and Control). One of the vehicles of transmission of this disease is milk. Nanostructured MOS (Metal Oxide Semiconductor) sensors have extensively demonstrated their ability to reveal the presence and follow the development of microbial species. The main objective of this work was to find a set up for the detection and development follow up of C. jejuni in milk samples. The work was structured in two different studies, the first one was a feasibility survey and the second one was to follow up the development of the bacteria inside milk samples. The obtained results of the first study demonstrate the ability of the sensor array to differentiate the contaminated samples from the control ones. Thanks to the second study, it has been possible to find the limit of microbial safety of the contaminated milk samples.