Environmental Samples Research Articles

Mortality partitioning between viral lysis and microzooplankton grazing in successive phytoplankton blooms using dilution and molecular methods

Phytoplankton play crucial roles in aquatic ecosystems, serving as the foundation of marine food webs and being responsible for ~50% of the world’s oxygen production. Predation by microzooplankton and viral lysis are the major sources of phytoplankton mortality, with the balance between these 2 processes affecting microbial food webs and biogeochemical cycles. However, determining the dominant mortality process in time and space remains an open question. This study investigated microzooplankton grazing and viral lysis rates during a mesocosm experiment in western Norway. High-resolution measurements were determined on phytoplankton groups using flow cytometry to observe changes in mortality rates and carbon flow during phytoplankton blooms. Digital droplet PCR was employed to detect Emiliania huxleyi and Micromonas spp. and associated viruses within environmental samples, to explore its use for determining mortality processes and understanding the impact on the phytoplankton community. The results showed that grazing and viral lysis dominated mortality at different times, with only one significant instance of both processes being observed. Microzooplankton grazing primarily affected picoplankton, while nanoeukaryotes and E. huxleyi were more susceptible to viral lysis. Molecular detection did not always match with abundances or rates determined by flow cytometry; however, it did provide insights into their dynamics throughout the mesocosm. These findings provide insights into the complex interactions between microzooplankton, viruses and phytoplankton communities. Understanding the balance between microzooplankton grazing and viral lysis can contribute to a more comprehensive understanding of carbon flow in aquatic ecosystems, which has significant implications for food webs and biogeochemical cycles.

Multi-scenario surveillance of respiratory viruses in aerosols with sub-single-copy spatial resolution

Highly sensitive airborne virus monitoring is critical for preventing and containing epidemics. However, the detection of airborne viruses at ultra-low concentrations remains challenging due to the lack of ultra-sensitive methods and easy-to-deployment equipment. Here, we present an integrated microfluidic cartridge that can accurately detect SARS-COV-2, Influenza A, B, and respiratory syncytial virus with a sensitivity of 10 copies/mL. When integrated with a high-flow aerosol sampler, our microdevice can achieve a sub-single-copy spatial resolution of 0.83 copies/m3 for airborne virus surveillance with an air flow rate of 400 L/min and a sampling time of 30 minutes. We then designed a series of virus-in-aerosols monitoring systems (RIAMs), including versions of a multi-site sampling RIAMs (M-RIAMs), a stationary real-time RIAMs (S-RIAMs), and a roaming real-time RIAMs (R-RIAMs) for different application scenarios. Using M-RIAMs, we performed a comprehensive evaluation of 210 environmental samples from COVID-19 patient wards, including 30 aerosol samples. The highest positive detection rate of aerosol samples (60%) proved the aerosol-based SARS-CoV-2 monitoring represents an effective method for spatial risk assessment. The detection of 78 aerosol samples in real-world settings via S-RIAMs confirmed its reliability for ultra-sensitive and continuous airborne virus monitoring. Therefore, RIAMs shows the potential as an effective solution for mitigating the risk of airborne virus transmission.

Genomically-supported Redefinition of an Outbreak in a Pediatric Unit Caused by blaVIM -harboring Klebsiella michiganensis.

Klebsiella michiganensis , a member of the Klebsiella oxytoca complex, is an emerging nosocomial pathogen known to frequently carry plasmids with antibiotic-resistance genes, including carbapenemases. Using genomics, this study redefined an outbreak alert of K. michiganensis carrying a blaVIM carbapenemase in a pediatric ward in a Spanish hospital. A total of 31 isolates of Verona integron-encoded metallo-β-lactamase (VIM)-carbapenemase K. oxytoca from suspected outbreak cases and unrelated controls from 2015 to 2022 were analyzed. Whole-genome sequencing (both short and long reads) was applied to determine phylogenetic relationships based on single-nucleotide polymorphisms (SNPs) and identify plasmids and antimicrobial resistance genes. The sequences from 12 isolates identified in 2021 showed pairwise SNP distances ranging from 0 to 16 SNPs, confirming the outbreak. Examination of isolates before and after the study period revealed 7 additional cases, 2 in 2020 and 5 in 2022. The outbreak comprised 18 isolates from 17 patients in 3 different pediatric wards, together with 1 environmental sample. In all outbreak isolates, the blaVIM-1 gene was located within a gene cassette carried by a class 1 integron on an IncFIB(pQil) plasmid. A genomic network based on SNPs revealed 5 unsampled intermediate nodes, suggesting additional subclones that may have involved healthcare staff, patient relatives or environmental reservoirs. Blood and rectal isolates obtained from the same patient were positioned on separate branches of the network, making a direct evolutionary pathway between them unlikely. Our study redefined the full extent of this K. michiganensis -VIM outbreak and highlights the critical importance of genomic analysis in accurately understanding outbreaks in healthcare settings.

Exploring consumer acceptability of leafy greens in earth and space immersive environments using biometrics

Novel research on food perception is required for long-term space exploration. There is limited research on food/beverage sensory analysis in space and space-simulated conditions, with many studies presenting biases in sensory and statistical methods. This study used univariate and multivariate analysis on data from pick-and-eat leafy greens to assess self-reported and biometric consumer sensory analysis in simulated microgravity using reclining chairs and space-immersive environments. According to ANOVA (p < 0.05), there were significant differences between interaction room × position for head movements; besides, there were non-significant differences in the interaction samples × environment. On the other hand, there were significant differences in the sample×position interaction for all liking attributes. Results from multivariate analysis showed effects on self-reported, physiological, and emotional responses of samples in space-related positions and environments related to sensory perception changes. Non-invasive biometrics could offer a powerful tool for developing digital twins to assess genetically modified plants and plant-based food/beverages for long-term space exploration.

Adipogenic Effects of Cresyl Diphenyl Phosphate (Triphenyl Phosphate Alternative) through Peroxisome Proliferator-Activated Receptor Gamma Pathway: A Comprehensive Study Integrating In Vitro, In Vivo, and In Silico from Molecule to Health Risk.

Cresyl diphenyl phosphate (CDP), a novel organophosphate ester (OPE), has been detected in various environmental and human samples. However, there is very limited knowledge regarding its toxicity, mechanisms of action, and potential health risks. Using new alternative methods (NAMs), across the molecular interactions, signaling pathways, cell functions, animal effects, and population risks, we investigated the potential adipogenic effects and associated risks of CDP and legacy OPE triphenyl phosphate (TPHP) by acting on peroxisome proliferator-activated receptor gamma (PPARγ). Among the 19 screened OPEs, CDP bound to PPARγ with the highest binding potency, followed by TPHP. CDP activated PPARγ through fitting into the binding pocket with strong hydrophobicity and hydrogen bond interactions; CDP exhibited higher potency compared to TPHP. In 3T3-L1 cells, CDP enhanced the PPARγ-mediated adipogenesis activity, exhibiting greater potency than TPHP. The intracellular concentration and receptor-bound concentrations (RBC) of CDP were also higher than those of TPHP in both HEK293 cells and 3T3-L1 cells. In mice, exposure to CDP activated the PPARγ-mediated adipogenic pathway, leading to an increased white adipose tissue weight gain. Overall, CDP could bind to and activate PPARγ, thereby promoting preadipocyte differentiation and the development of white adipose tissue. Its potential obesogenic risks should be of high concern.

Rapid and accurate identification of multiple metal ions using a bispyrene‐based fluorescent sensor array with aggregation‐induced enhanced emission property

AbstractMultiple metal ions are traditionally detected using inductively coupled plasma mass spectrometry (ICP‐MS) and atomic fluorescence spectrometry. Although these methods are sensitive and accurate, they depend on complex instruments and require highly trained operators, making low costly rapid detection challenging. It is urgent to develop a convenient, rapid and sensitive method to detect multiple metal ions. Herein, we designed a bispyrene derivative (BP) with aggregation‐induced enhanced emission (AIEE) property to construct a high fluorescent sensor array to realize the effective identification of four metal ions (Fe3+, Cu2+, Co2+ and Cd2+). The differential coordination capability between metal ions and BP with the aid of acetate ions resulted the possibility of array‐based sensing. The four heavy metal ions could be immediately classified in the concentration of 100 nM. The limit of detection (LOD) of Fe3+, Cu2+, Co2+, and Cd2+ were as low as 16.2, 21.8, 51.4, and 25.9 nM, respectively. Furthermore, the sensor array was applied for identification multiple heavy metal ions in environmental samples and iron ion in rat serums with identified of 100%. The sample consumption as low as 2 µL for each detection and the results could be extracted by smartphones under ultraviolet lamps. It provided a rapid, sensitive, low‐cost, and on‐site multiple metal ions detection method.

A multi-pathogen behavioral exposure model for young children playing in public spaces in developing communities.

Diarrheal disease is the second leading cause of death among children under five in developing communities, despite active interventions to improve access to water, sanitation, and hygiene resources. Even interventions with high fidelity and compliance saw minimal improvements in health outcomes, necessitating a need for looking beyond traditionally targeted exposure pathways. This study focuses on the pathogen exposure a young child may receive while playing in the public spaces of informal settlements, where animal feces, human feces, and garbage are frequently observed. The study utilized 79 soil samples previously collected across ten cluster sites in Corail, Haiti and processed using DelAgua cultural assays and quantitative Polymerase Chain Reaction methods. Molecular assays screened for Aeromonas, Vibrio cholera, and several pathogenic Escherichia coli species. Behavioral observations of young children (<5 years old) were also conducted in overlapping areas with the environmental sampling to quantify frequency of risky and mitigating behaviors. Environmental and behavioral data were combined to obtain the posterior distribution of children's pathogen exposure from playing in a public space for one hour. The model estimated that children have a likelihood of approximately 70% of being exposed to a pathogen during one hour of play and a greater than 30% chance of being exposed to multiple pathogens in the same period. While children and toddlers practice fewer risky behaviors compared to infants, they were shown to have higher likelihood of exposure and slightly higher pathogen dose per exposure. As anticipated, a high correlation between genes from the same E. coli species was observed in the model output. These findings demonstrate the need to consider public spaces as an important exposure pathway for young children for both future research and interventions.

Molecular epidemiology of avian influenza viruses and avian coronaviruses in environmental samples from migratory bird inhabitants in Bangladesh

Migratory birds are a natural reservoir for major respiratory viruses such as the avian influenza virus (AIV) and the avian coronavirus (AvCoV). Transmission of these viruses from migratory birds to domestic birds increases the prevalence of those diseases that cause severe economic and public health concerns in Bangladesh. The study focused on active surveillance of major respiratory viral pathogens in migratory birds, molecular identification of the viruses, and their phylogenetic origin. To conduct this study, 850 environmental samples (830 fecal samples, 10 soil samples, and 10 water samples) were collected during three consecutive winter seasons from three divisions (Dhaka, Sylhet, and Mymensingh) and pooled according to the year of collection and locations, resulting in a total of 184 tested samples. Using gene-specific primers and probes in TaqMan-and SYBR Green-based RT-qPCR assays, the samples were screened for AIV and AvCoV, respectively. Out of the 184 pooled samples, 37 were found to be positive for these respiratory pathogens. Furthermore, out of the 37 (20.11%) positive respiratory pathogens, 11.96% were AIV (n = 22) and 8.15% were AvCoV (n = 15). For the first time in Bangladesh, AIV H4N2, H4N6, and AvCoVs have been found in fecal samples from migratory birds through surveillance. Phylogenetic analyses of the HA and NA genes of AIV and the polymerase gene (Orf 1) of AvCoV revealed that these strains share a close phylogenetic relationship with the isolates from wild birds in Europe and Asia. The Bangladeshi strains with Eurasian ancestry might pose a significant threat to migratory birds flying through the Asian flyways. They might also be a potential source of virus introduction and spread to poultry raised on land. These findings emphasize the significance of ongoing AIV and AvCoV surveillance in migratory birds in Bangladesh.

Biofilm-mediated interactions between plastics and radiocesium in coastal environments.

A ubiquitous distribution of plastic debris has been reported in aquatic and terrestrial environments; however, the interactions between plastics and radionuclides and the radioactivity of environmental plastics remain largely unknown. Here, we characterize biofilms developing on the surface of plastic debris to explore the role of plastic-associated biofilms as an interaction medium between plastics and radiocesium (137Cs) in the environment. Biofilm samples were extracted from plastics (1-50mm in size) collected from two contrasting coastal areas in Japan. The radioactivity of plastics was estimated based on the 137Cs activity concentration of the biofilms and compared seasonally with surrounding environmental samples (i.e., sediment and sand). 137Cs traces were detected in biofilms with activity concentrations of 21-1300Bq·kg-1 biofilm (dry weight), corresponding to 0.04-4.5Bq·kg-1 plastic (dry weight). Our results reveal the interaction between 137Cs and plastics and provide evidence that organic and mineral components in biofilms are essential in 137Cs retention in environmental plastics. Given the ubiquitous distribution of plastic debris in the environment, more attention should be directed to bioaccumulation and the radioecological impacts of plastic-associated radionuclides on ecosystems.

Determining personal exposure to high production volume chemicals (HPVCs) and polycyclic aromatic hydrocarbons (PAHs) with silicone wristbands: A pilot study

High production volume chemicals (HPVCs) and polycyclic aromatic hydrocarbons (PAHs) are semi-volatile organic compounds (semi-VOCs) of great environmental concern because of their presence worldwide and health problems resulting from long-term exposure to some of them. It is essential to have robust analytical methods to monitor the concentrations of these compounds not only in environmental samples but also individual exposure. In this pilot study we develop and validate a multiresidue analytical method based on ultrasound-assisted extraction and gas-chromatography mass spectrometry for the simultaneous determination of 56 semi-VOCs using silicone wristbands (SWBs) as personal passive samplers. The developed method provided recoveries between 43% and 114% on sampled SWBs and method detection and quantification limits in the range of 0.1 - 35 ng/g and 0.3 - 119 ng/g, respectively. A preliminary study was performed with a small group of adults living in the industrial city of Tarragona (north-eastern Spain) to evaluate the applicability of SWBs for monitoring individual exposure to the studied HPVCs and PAHs. Benzothiazoles, benzenesulfonamides, UV stabilisers and phenolic antioxidants were determined for the first time in SWBs. Phthalates (PAEs), stood out above the rest, accounting for 52% of the total concentrations. Diethylhexyl phthalate was the compound found at the highest concentrations with values between 1.1 - 82 μg/g. Carcinogenic and non-carcinogenic dermal risk assessment was performed for adults and considering two scenarios (low and high). PAHs were the compounds with the highest carcinogenic and non-carcinogenic dermal risk regardless of the exposure scenario. The second family of compounds that contributed the most to the total risk were PAEs but high punctual concentrations of these compounds caused significant differences between exposure scenarios.

Impacts of iodoacetic acid on reproduction: current evidence, underlying mechanisms, and future research directions

In light of the undeniable and alarming fact that human fertility is declining, the harmful factors affecting reproductive health are garnering more and more attention. Iodoacetic acid (IAA), an emerging unregulated drinking water disinfection byproduct, derives from chlorine disinfection and is frequently detected in the environment and biological samples. Humans are ubiquitously exposed to IAA daily mainly through drinking water, consuming food and beverages made from disinfected water, contacting swimming pools and bath water, etc. Mounting evidence has indicated that IAA could act as a reproductive toxicant and bring about multifarious adverse reproductive damage. For instance, it can interfere with gonadal development, weaken ovarian function, impair sperm motility, trigger DNA damage to germ cells, perturb steroidogenesis, etc. The underlying mechanisms predominantly include cytotoxic and genotoxic effects on germ cells, disturbance of the hypothalamic–pituitary-gonadal axis, oxidative stress, inhibition of steroidogenic proteins or enzymes, and dysbiosis of gut microbiota. Nevertheless, there are still some knowledge gaps and limitations in studying the potential impact of IAA on reproduction, which urgently need to be addressed in the future. We suppose that necessary population epidemiological studies, more sensitive detection methods for internal exposure, and mechanism-based in-depth exploration will contribute to a more comprehensive understanding of characteristics and biological effects of IAA, thus providing an important scientific basis for revising sanitary standards for drinking water quality.

You can bring plankton to fecal indicator organisms, but you cannot make the plankton graze: particle contribution to E. coli and MS2 inactivation in surface waters.

Organisms that are associated with feces ("fecal indicator organisms") are monitored to assess the potential for fecal contamination of surface water bodies in the United States. However, the effect of the complex mixtures of chemicals and the natural microbial community within surface water ("particles") on fecal indicator organism persistence is not well characterized. We aimed to better understand how particles, including biological (e.g., potential grazers) and inert (e.g., minerals) types, affect the fecal indicator organisms Escherichia coli K-12 ("E. coli") and bacteriophage MS2 in surface waters. A gradient of particles captured by a 0.2-µm-pore-size filter ("large particles") was generated, and the additional particles and dissolved constituents that passed through the filter were deemed "small particles." We measured the ratio of MS2 and E. coli that survived over a 24-h incubation period for each condition (0%-1,000% large-particle concentration in raw water) and completed a linear regression that included large- and small-particle coefficients. Particles were characterized by quantifying plankton, total bacterial cells, and total solids. E. coli and MS2 persistence was not significantly affected by large particles, but small particles had an effect in most waters. Small particles in higher-salinity waters had the largest, negative effect on E. coli and MS2 survival ratios: Significant small-particle coefficients ranged from -1.7 to -5.5 day-1 in the marine waters and -0.89 to -3.2 day-1 in the fresh and estuarine waters. This work will inform remediation efforts for impaired surface water bodies.IMPORTANCEMany surface water bodies in the United States have organisms associated with fecal contamination that exceed regulatory standards and prevent safe recreation. The process to remediate impaired water bodies is complicated because these fecal indicator organisms are affected by the local environmental conditions. For example, the effect of particles in surface water on fecal indicator concentrations are difficult to quantify in a way that is comparable between studies and water bodies. We applied a method that overcomes this limitation to assess the effects of large particles, including natural plankton that could consume the seeded fecal indicator organisms. Even in environmental water samples with diverse communities of plankton present, no effect of large particles on fecal indicator concentrations was observed. These findings have implications for the interpretation and design of future studies, including that particle characterization of surface water may be necessary to assess the fate of fecal indicators.

Wastewater and environmental sampling holds potential for antimicrobial resistance surveillance in food-producing animals - a pilot study in South African abattoirs

Wastewater and environmental sampling holds potential for antimicrobial resistance surveillance in food-producing animals - a pilot study in South African abattoirs

Development of CadR-based cadmium whole cell biosensor for visual detection of environmental Cd2+

BackgroundAs a threat to human health and public health, cadmium (Cd) pollution has received widespread social concern. Our previously constructed CadR-based bacterial whole cell biosensor (WCB) epCadR5 showed high sensitivity and specificity in cadmium detection. However, the application of the sensor is still hindered by the need for laboratory equipment to read the fluorescence signal output. In this study, we aimed to optimizing the sensor to make it available for visual detection of environmental cadmium and simplify the detection process to advance practical application of the sensor. ResultsBy replacing the constitutive promoter with J110, the fluorescence signal output of the sensor was significantly increased and the fluorescence leakage was decreased. In addition, the fluorescence signal output of green fluorescence protein (GFP) was enhanced by the addition of a 5′ untranslated region (5′-UTR) mlcR10. The fluorescence signal output of the WCB is sufficiently robust to be visible and distinguishable to the naked eye, which is of paramount importance for visual detection. The sensor readout can be conveniently recorded by mobile phone camera and quantified. For ease of on-site application, the WCB's visual detection procedures and conditions were further optimized and simplified. The WCB demonstrated good linearity and detection limit (1.81 μg/L) for visual detection of Cd2+ without the assistance of bulky laboratory equipment. For the detection of real environmental samples, the WCB visual detection results were close to those of WCB-flow cytometry (FACS) and graphite furnace atomic absorption spectroscopy (GFAAS). SignificanceIn this work, we developed an easy-to-use, on-site and visual detection biosensor for monitoring environmental Cd2+. It will advance the utilization of cadmium WCBs in practical settings. The optimization and simplification strategy in the study also provide new insights into the visualization of other bacterial biosensors, and will advance the practical application of WCBs.

B-228 Performance Comparison of three viral RNA pathogens in MK Buffered Solution for Diagnostic Based Detection using quantitative PCR vs droplet digital PCR

Abstract Background Droplet digital PCR (ddPCR) by partitioning a single reaction into many thousands of nano-droplets allows for the absolute quantitation of a given DNA/RNA target and represents the gold standard for the identification and quantification of pathogens in clinical and environmental samples. While nucleic acid based molecular diagnostics have become fundamental for the accurate and rapid quantification of specific pathogens, these instruments are still based upon quantitative PCR (QPCR) assays. The goal of this study was to assess the compatibility of a MK Buffered solution with three different RNA viruses combined into two standard clinical negative matrices and compare performance of ddPCR and QPCR for all three pathogens. Methods Serial dilutions of heat-inactivated Sars-CoV-2 (NR-52286), Influenza A (ATCC VR-1469) and RSV-A (ATCC strain VR-26) were combined into a single tube and added to two confirmed clinically negative matrices, Nasal and Sputum (Lee Biosolutions, Maryland Heights, MO). Serial dilutions of the combined pathogens were added to sample tubes containing 500 µL of MK buffered solution yielding final concentrations of each pathogen over 4 orders of magnitude in each clinical matrix. For each sample 300 µl was processed for RNA isolation using standard RNA isolation kits (Zymo Viral RNA Kit). For ddPCR samples were quantified for all three pathogens using a BioRad® Droplet Digital PCR System (QXD200). For QPCR, samples were quantified using Quantitative real-time PCR using Promega GoTaq® Probe 1- Step RT-qPCR System. The same TAQMan® probes specific for each pathogen were used for both systems. Results Yields of all three viral RNAs were significantly lower from sputum samples as compared to nasal samples. For all three pathogens the ddPCR assay was an order of magnitude more sensitive than observed with QPCR. QPCR and ddPCR values showed a significant linear relationship for all three pathogens (Sars-CoV-2, r2 = 0.984; RSV A, r2 = 0.814; Influenza A, r2 = 0.985). Conclusions QPCR and Droplet digital PCR accurately quantified concentrations of all three RNA pathogens in both clinically negative nasal and sputum matrices across four orders of magnitude, though detected yields were significantly lower in samples spiked into the sputum matrix. For all three pathogens there was a significant linear relationship with decreasing concentration. ddPCR was an order of magnitude more sensitive than QPCR for all three pathogens.

Rapid and selective removal of bisphenol S from environmental samples by surface-imprinted polymer synthesized based on metal-organic framework MIL-101(Cr)

In this study, a novel, surface-imprinted polymer (MIL-101@MIP) was successfully synthesized using the metal-organic framework MIL-101(Cr) with a large specific surface area as a carrier, which achieved rapid and selective removal of bisphenol S (BPS) from environmental samples. The structure and morphology of MIL-101@MIP were characterized using SEM, XPS, FTIR, TGA, BET, and XRD techniques. The results show that MIL-101@MIP has rough surface morphology and good thermal stability. The large specific surface area (1251.6 m2 g-1) of MIL-101@MIP provides more imprinting sites in MIL-101@MIP; thus, the maximum adsorption capacity of BPS reached 87.76mgg-1 with good imprinting factor 2.08, and equilibrium was achieved in only 10min. Moreover, the process of BPS adsorption onto MIL-101@MIP followed the pseudo-second-order kinetics and Langmuir isothermal adsorption models. In addition, the MIL-101@MIP was utilized as an adsorbent for a solid phase extraction column to determine BPS in seven environmental samples using HPLC, achieving recovery of 89.20–105.78%. The developed MIL-101@MIP is a promising and efficient adsorbent for rapid and selective removal of BPS from the environment.

Green synthesis of thiazole bis-imines as fluorometric sensor for determination of lead in environmental, biological, and food samples

In this work, we describe for the first time the synthesis of a thiazole bis-imine fluorometric sensor for the selective determination of Pb2+ in environmental, biological, and food samples. The novel molecules were obtained through a multicomponent reaction using a green and environmentally sustainable methodology. Synthesized chemical sensors were characterized using spectroscopic techniques to structural elucidation, including UV–Vis, FTIR-ATR, 1H and 13C NMR. One of these sensors exhibited remarkable selectivity for the Pb2+ ion at pH 3, forming a stable 1:1 (metal:ligand) complex. Additionally, the reaction conditions for complex formation were optimized, resulting in a method with a linear range of 0.667 to 10 μg L−1 and a detection limit of 0.18 μg L−1. Furthermore, method validation reinforced its reliability, showing low relative standard deviation in both intra-day and inter-day analyses. Recovery experiments ranged from 83.53 % to 119.10 %. This study represents a significant and innovative advancement in the development of rapid, sensitive, and alternative methods for the detection of potentially toxic metals in a wide range of samples employing a green multicomponent reaction of thiazole bis-imines.

Environmental monitoring of Listeria monocytogenes contamination in dairy processing facilities combining culturing technique and molecular methods

Objectiveof the present study was to investigate Listeria contamination in Sardinian sheep cheese-making plants using culture and DNA-based methods. Food and environmental samples were collected from different surfaces of 14 facilities. Samples were collected using pre-moistened sponge swabs. Each site was sampled using two sponges used one for microbiological detection and the other for extraction of total DNA. The DNA was submitted to real time PCR targeting the prs gene for Listeria spp., the gene inlA for Listeria monocytogenes and the gene iap for Listeria innocua. DNA metabarcoding was also conducted on the total DNA. Overall were collected 254 environmental and 36 food samples. The prevalence of Listeria spp. and Listeria monocytogenes was 18.6% and 10.0%, respectively. Samples enrichment coupled with quantitative PCR (qPCR) showed a greater sensitivity than the conventional culture method with an overall prevalence of 12.1% for L. monocytogenes. Both, qPCR and ribosomal DNA-metabarcoding conducted on total DNA extracted from the sponges performed poorly in comparison to the culture-based method detecting the presence of Listeria genus in as little as 7 (2.4%) and 4 (1.4%) samples respectively. The present study supports the use of a culture enrichment coupled with qPCR for routine monitoring of contamination in food premises.

Microbial composition and dynamics in environmental samples from a ready-to-eat food production facility with a long-term colonisation of Listeria monocytogenes

Microbial composition and dynamics in environmental samples from a ready-to-eat food production facility with a long-term colonisation of Listeria monocytogenes

Simultaneous Determination of Lead and cadmium in Environmental Samples Using Zinc-diethyldithiocarbamates

تمتلك المعادن الثقيلة السامة تأثيرا خطيرا على البيئة ، وان عملية التقدير الكمي لتركيزهذه المعادن يعطي معلومات مهمة تخص سمية المعادن. في هذه الدراسة تم استخدام طريقة تحليلية طيفية سهلة ، سريعة وانتقائية مع طريقة الاستخلاص بالطورالصلب للتقديرالمتزامن للرصاص والكادميوم في النماذج البيئية باستخدام الزنك - ثنائي إيثيل ثيوكاربامات المترسب ككاشف. تم استخدام طريقة الاستخلاص بالطور الصلب لعملية لتركيز المسبق لمحتوى الرصاص والكادميوم في النماذج البيئية. أظهرت الطريقة المقترحة مدى خطية يتراوح بين 0,1 – 16 مايكروغرام/مل و 0,1 – 14 مايكروغرام/مل لكل من الرصاص والكادميوم على التوالي. وكانت قيمة الاستردادية تتراوح بين 90 – 96 % مع معامل ارتباط (ر2) مقداره 0,9985 و 0,9989 لكل من الرصاص والكادميوم على التوالي. تم دراسة الظروف المثلى مثل (قيمة الاس الهيدروجيني ، وقت الاستخلاص و حجم الطورالمائي) على كفاءة عملية الاستخلاص للمعادن بالاضافة الى دراسة تأثير وجود الاملاح والايونات الاخرى كمتداخلات. تم تطبيق الطريقة المقترحة في الدراسة على عدد من النماذج البيئية (التربة والماء) لتقدير كمية العناصر الموجودة فيها. اظهرت النتائج المستحصلة دقة وانتقائية جيدة تدل على امكانية استخدام الطريقة المقترحة في تقدير الرصاص والكادميوم وامكانية تطبيقها في مجالات اخرى.