Formation and recovery of Listeria monocytogenes in viable but nonculturable state under different temperatures combined with low nutrition and high NaCl concentration.

The viable but nonculturable (VBNC) state occurs when bacteria lose their ability to grow and multiply on conventional media when stressed by adverse environmental factors, but they remain active and can revive under certain conditions, posing a food safety risk. In this study, the VBNC state of Listeria monocytogenes was induced with different temperatures combined with low nutrient conditions; the VBNC state of L. monocytogenes was confirmed in conjunction with the housekeeping gene abcZ using a molecular biology assay (PMA-qPCR) to calculate the viable bacterial count; The resuscitation conditions for the VBNC state of L. monocytogenes were investigated utilizing various nutrients in the culture medium and pasteurized milk. Four strains of L. monocytogenes reached the VBNC stage after 14, 21, 21, and 35 days at 20°C with 20% (or 30%) NaCl. Resuscitation studies indicate that Trypticase Soy Broth (TSB) combined with Tween 80 and sodium pyruvate is more effective for resuscitation. The Chinese national standard technology GB 4789.30-2016 was used to inoculate lettuce, chicken, and pasteurized milk with L. monocytogenes ATCC 19115 VBNC state. This research has significant implications for commercial food processing, long-term storage, disinfection, disease prevention, and control.

Assessment of Multifunctional Activity of a Postbiotic Preparation Derived from Lacticaseibacillus paracasei Postbiotic-P6.

Postbiotics possess various functional activities, closely linked to their source bacterial strains and preparation methods. Therefore, the functional activities of postbiotics need to be evaluated through in vitro and in vivo methods. This study aims to prepare a postbiotic and explore its antihemolytic, anti-inflammatory, antioxidant, and antibacterial activities. Specifically, a postbiotic preparation named PostbioP-6 was prepared by intercepting 1-5 kDa of Lacticaseibacillus paracasei Postbiotic-P6 fermentation broth. The results demonstrate that PostbioP-6 exhibited notable biological activities across multiple assays. It showed significant antihemolytic activity, with a 4.9-48.1% inhibition rate at 10-50% concentrations. Anti-inflammatory effects were observed both in vitro, where 8-40% PostbioP-6 was comparable to 259.1-645.4 µg/mL diclofenac sodium, and in vivo, where 3.5 and 4.0 µL/mL PostbioP-6 significantly reduced neutrophil counts in inflamed zebrafish (p < 0.05). Antioxidant properties were evident through increased reducing power (OD700 increased from 0.279 to 2.322 at 1.25-12.5% concentrations), DPPH radical scavenging activity (38.9-92.4% scavenging rate at 2.5-50% concentrations), and hydroxyl radical scavenging activity (4.66-10.38% scavenging rate at 0.5-4% concentrations). Additionally, PostbioP-6 demonstrated antimicrobial activity against two Gram-positive bacteria, eight Gram-negative bacteria, and one fungus. Furthermore, PostbioP-6 significantly inhibited the increase in peroxide value and malondialdehyde content in cookies, highlighting its potential application in food preservation. In conclusion, we prepared a novel postbiotic, termed PostbioP-6, which proved to have prominent anti-hemolytic, anti-inflammatory, antioxidant, and broad-spectrum antimicrobial activities. The multifunctional properties of PostbioP-6 position it as a potentially effective functional food supplement or preservative. In the future, further research is necessary to elucidate the precise mechanisms of action, identify the active components, and validate its biological activities in animal models or clinical trials.

Simultaneous SERS-decoding detection of multiple pathogens in drinking water with home-made portable double-layer filtration and concentration device.

The engineering of a home-made portable double-layer filtration and concentration device with the common syringe for rapid analysis of water samples is reported. The core elements of the device were two installed filtration membranes with different pore sizes for respective functions. The upper filtration membrane was used for preliminary intercepting large interfering impurities (interception membrane), while the lower filtration membrane was used for collecting multiple target pathogens (enrichment membrane) for determination. This combination can make the contaminated environmental water, exemplified by surface water, filtrated quickly through the device and just retained the target bacteria of Escherichia coli O157:H7, Staphylococcus aureus, and Listeria monocytogenes on the lower enrichment membrane. Integrating with surface-enhanced Raman spectra (SERS) platform to decode the SERS-Tags (SERS-TagCVa, SERS-TagR6G, and SERS-TagMB) already labeled on each of the enriched bacteria based the antibody-mediated immuno-recognition effect, fast separation, concentration, and detection of multiple pathogenic bacteria from the bulk of contaminated environmental water were realized. Results show that within 30 min, all target bacteria in the lake water can be simultaneously and accurately measured in the range from 101 to 106 CFU mL-1 with detection limit of 10.0 CFU mL-1 without any pre-culture procedures. This work highlights the simplicity, rapidness, cheapness, selectivity, and the robustness of the constructed method for simultaneous detecting multiple pathogens in aqueous samples. This protocol opens a new avenue for facilitating the development of versatile analytical tools for drinking water and food safety monitoring in underdeveloped or developing countries.

Differences in Biofilm Formation of Listeria monocytogenes and Their Effects on Virulence and Drug Resistance of Different Strains.

Listeria monocytogenes is recognized as one of the primary pathogens responsible for foodborne illnesses. The ability of L. monocytogenes to form biofilms notably increases its resistance to antibiotics such as ampicillin and tetracycline, making it exceedingly difficult to eradicate. Residual bacteria within the processing environment can contaminate food products, thereby posing a significant risk to public health. In this study, we used crystal violet staining to assess the biofilm-forming capacity of seven L. monocytogenes strains and identified ATCC 19112 as the strain with the most potent biofilm-forming. Subsequent fluorescence microscopy observations revealed that the biofilm-forming capacity was markedly enhanced after two days of culture. Then, we investigated into the factors contributing to biofilm formation and demonstrated that strains with more robust extracellular polymer secretion and self-agglutination capabilities exhibited a more pronounced ability to form biofilms. No significant correlation was found between surface hydrophobicity and biofilm formation capability. In addition, we found that after biofilm formation, the adhesion and invasion of cells were enhanced and drug resistance increased. Therefore, we hypothesized that the formation of biofilm makes L. monocytogenes more virulent and more difficult to remove by antibiotics. Lastly, utilizing RT-PCR, we detected the expression levels of genes associated with biofilm formation, including those involved in quorum sensing (QS), flagellar synthesis, and extracellular polymer production. These genes were significantly upregulated after biofilm formation. These findings underscore the critical relationship between extracellular polymers, self-agglutination abilities, and biofilm formation. In conclusion, the establishment of biofilms not only enhances L. monocytogenes' capacity for cell invasion and adhesion but also significantly increases its resistance to drugs, presenting a substantial threat to food safety.

Chronic sleep fragmentation reduces left ventricular contractile function and alters gene expression related to innate immune response and circadian rhythm in the mouse heart.

Sleep disorders have emerged as a widespread public health concern, primarily due to their association with an increased risk of developing cardiovascular diseases. Our previous research indicated a potential direct impact of insufficient sleep duration on cardiac remodeling in children and adolescents. Nevertheless, the underlying mechanisms behind the link between sleep fragmentation (SF) and cardiac abnormalities remain unclear. In this study, we aimed to investigate the effects of SF interventions at various life stages on cardiac structure and function, as well as to identify genes associated with SF-induced cardiac dysfunction. To achieve this, we established mouse models of chronic SF and two-week sleep recovery (SR). Our results revealed that chronic SF significantly compromised left ventricular contractile function across different life stages, leading to alterations in cardiac structure and ventricular remodeling, particularly during early life stages. Moreover, microarray analysis of mouse heart tissue identified two significant modules and nine hub genes (Ddx60, Irf9, Oasl2, Rnf213, Cmpk2, Stat2, Parp14, Gbp3, and Herc6) through protein-protein interaction analysis. Notably, the interactome predominantly involved innate immune responses. Importantly, all hub genes lost significance following SR. The second module primarily consisted of circadian clock genes, and real-time PCR validation demonstrated significant upregulation of Arntl, Dbp, and Cry1 after SF, while subsequent SR restored normal Arntl expression. Furthermore, the expression levels of four hub genes (Ddx60, Irf9, Oasl2, and Cmpk2) and three circadian clock genes (Arntl, Dbp, and Cry1) exhibited correlations with structural and functional echocardiographic parameters. Overall, our findings suggest that SF impairs left ventricular contractile function and ventricular remodeling during early life stages, and this may be mediated by modulation of the innate immune response and circadian rhythm. Importantly, our findings suggest that a short period of SR can alleviate the detrimental effects of SF on the cardiac immune response, while the influence of SF on circadian rhythm appears to be more persistent. These findings underscore the importance of good sleep for maintaining cardiac health, particularly during early life stages.

Rapid Nucleic Acid Detection of Listeria monocytogenes Based on RAA-CRISPR Cas12a System.

Listeria monocytogenes (L. monocytogenes) is a food-borne pathogenic bacteria that frequently contaminates animal-derived food and low-temperature preserved food. Listeriosis caused by its infection has a high mortality rate and poses a serious threat to human health. Therefore, it is crucial to establish a sensitive, rapid and easy-to-operate technique. In this study, a Recombinase Aided Amplification (RAA) assisted CRISPR/Cas12a (RAA-CRISPR/Cas12a) fluorescence platform was established for highly sensitive nucleic acid detection of L. monocytogenes. The established RAA-CRISPR/Cas12a showed high sensitivity and high specificity, with the sensitivity of 350 CFU/mL and 5.4 × 10-3 ng/µL for pure bacterial solution and genomic DNA, and good specificity for 5 strains of Listeria spp. and 14 strains of other common pathogenic bacteria. L. monocytogenes could be detected at an initial concentration of 2.3 CFU/25g within 2 h of enriching the beef in the food matrix, and this method could be applied to food samples that were easily contaminated with L. monocytogenes The results of RAA-CRISPR/Cas12a could be observed in 5 min, while the amplification was completed in 20-30 min. The speed and sensitivity of RAA-CRISPR/Cas12a were significantly higher than that of the national standard method. In conclusion, the RAA-CRISPR/Cas12a system established in this study has new application potential in the diagnosis of food-borne pathogens.

Desymmetrization and Parallel Kinetic Resolution of 1-Ethynylcyclobutanols via Asymmetric Cooperative Gold Catalysis.

Enantioselective gold catalysis remains a challenging area of research. By harnessing gold-ligand cooperation in the presence of a chiral bifunctional phosphine ligand featuring a novel 3'-phosphine oxide moiety, highly enantioselective desymmetrization of 1-ethynylcyclobutanols is achieved, permitting access to chiral α-methylenecyclopentanones featuring a diverse array of chiral quaternary and tertiary centers. This cooperative gold catalysis also enables parallel kinetic resolution in gold catalysis, delivering cyclopentanone regioisomers with excellent enantiomeric excesses. DFT calculations of the transition states support the distinct mechanism of asymmetric induction via controlling the conformation of the bound substrate and hence dictating the ring bond undergoing migration.

Robust Two-Dimensional Ferromagnetism in Cr5Te8/CrTe2 Heterostructure with Curie Temperature above 400 K.

The discovery of ferromagnetism in two-dimensional (2D) van der Waals crystals has generated widespread interest. The seeking of robust 2D ferromagnets with high Curie temperature (Tc) is vitally important for next-generation spintronic devices. However, owing to the enhanced spin fluctuation and weak exchange interaction upon the reduced dimensionalities, the exploring of robust 2D ferromagnets with Tc > 300 K is highly demanded but remains challenging. In this work, we fabricated air-stable 2D Cr5Te8/CrTe2 vertical heterojunctions with Tc above 400 K by the chemical vapor deposition method. Transmission electron microscopy demonstrates a high-quality-crystalline epitaxial structure between tri-Cr5Te8 and 1T-CrTe2 with striped moiré patterns and a superior ambient stability over six months. A built-in dual-axis strain together with strong interfacial coupling cooperatively leads to a record-high Tc for the CrxTey family. A temperature-dependent spin-flip process induces the easy axis of magnetization to rotate from the out-of-plane to the in-plane direction, indicating a phase-dependent proximity coupling effect, rationally interpreted by first-principles calculations of the magnetic anisotropy of a tri-Cr5Te8 and 1T-CrTe2 monolayer. Our results provide a material realization of effectively enhancing the transition temperature of 2D ferromagnetism and manipulating the spin-flip of the easy axis, which will facilitate future spintronic applications.

Anisotropic charge transfer and gate tuning for p-SnS/n-MoS2 vertical van der Waals diodes.

2D-material-based van der Waals heterostructures (vdWhs) have shown great potential in next-generation multi-functional microelectronic devices. Thanks to their sharp interface and ultrathin thickness, 2D p-n junctions with high rectification properties have been established by combining p-type monochalcogenides with n-type transition metal dichalcogenides. However, the anisotropic rectification together with the charge transfer and gate effect has not been clarified. Herein, the electrical anisotropy of p-SnS/n-MoS2 diodes was studied. Optimum ideality factors within 1.08-1.18 have been achieved for the diode with 6.6 nm thick SnS on monolayer MoS2, and a high rectification ratio of 3.1 × 104 with strong in-plane anisotropy is observed along the zigzag direction of SnS. A strong gate effect on the anisotropic series resistance has been verified and an effective tuning over the transport length of the SnS channel can be established through adjustment of the current orientation and gate voltage. A thickness-dependent minority carrier transport mechanism has also been demonstrated for the reverse drain current, and Fowler-Nordheim tunneling and direct tunneling are proposed for the increase of the reverse current of the thicker and thinner diodes, respectively. This work will provide another strategy for high-performance diodes based on vdWhs via the control of the current orientation and the gate effect.

A Comparable icELISA and Lateral Flow Immunoassay for the Sensitive and Rapid Detection of 4,4'-Dinitrocarbanilide in Chicken.

4,4'-dinitrocarbanilide (DNC) is a key component and marker residue of nicarbazin, which forms residues in edible tissue and then causes nephrotoxicity and hepatotoxicity in humans if used excessively. To simplify sample preparation and monitor the DNC rapidly and accurately, a comparable icELISA and lateral flow immunoassay (LFIA) was developed in this study. Briefly, the reaction parameters were explored for improving the sensitivity of icELISA and LFIA. Under the optimal conditions, methanol was selected as the extracting solvent for DNC in chicken, and 20- and 10-fold dilutions of sample extraction eliminated the matrix effect for icELISA and LFIA, separately. After sample pretreatment, the analysis properties of icELISA and LFIA were compared. The limit of detection of icELISA for DNC was 0.8 µg/kg, and the visual and quantitative limits of detection of LFIA were 8 and 2.5 µg/kg. Compared with icELISA, LFIA showed lower sensitivity but obvious advantages in terms of matrix tolerance and detection time (within 15 min). The sensitivity, specificity, and accuracy of the developed assays satisfied the detection requirement even if using simple sample pretreatment. This comparable icELISA and LFIA provided mutual verifiability methods for the accurate detection of DNC in chicken.

Health-related quality of life among ethnic minority residents in remote Western China: a cross-sectional study.

BACKGROUND: Paying attention to the health-related quality of life (HRQOL) of rural residents in poverty-stricken areas is an important part of China's poverty alleviation, but most studies on health-related quality of life have focused on rural residents, elderly individuals, and patients; evidence on the HRQOL of rural minority residents is limited. Thus, this study aimed to assess the HRQOL of rural Uighur residents in remote areas of Xinjiang, China, and determine its influencing factors to provide policy opinions for realizing a healthy China strategy. METHODS: A cross-sectional study was performed on 1019 Uighur residents in rural areas. The EQ-5D and self-administered questionnaires were used to assess HRQOL. We applied Tobit and binary logit regression models to analyse the factors influencing HRQOL among rural Uighur residents. RESULTS: The health utility index of the 1019 residents was - 0.197,1. The highest proportion of respondents reporting any problem was for mobility (57.5%), followed by usual activity (52.8%). Low levels of the five dimensions were related to age, smoking, sleep time, Daily intake of vegetables and fruit per capita. Gender, age, marital status, physical exercise, sleep duration, daily intake of cooking oil per capita, daily intake of fruit per capita, distance to the nearest medical institution, non-infectious chronic diseases (NCDs), self-rated health score, and participation in community activities were correlated with the health utility index of rural Uighur residents. CONCLUSIONS: HRQOL was lower for rural Uyghur residents than for the general population. Improving health behavioural lifestyles and reducing the incidence of poverty (return to poverty) due to illness are effective means of promoting the health in Uyghur residents. The region must fulfil the health poverty alleviation policy and focus on vulnerable groups and low-income residents to improve the health, ability, opportunity, and confidence of this population to live well.

Path Analysis of Influencing Factors of Depression in Middle-Aged and Elderly Patients with Diabetes.

Purpose: This study aimed to assess the prevalence of depression in middle-aged and elderly patients with diabetes in China, determine the risk factors of depression in these patients, and explore the internal relationship between influencing factors and depression by constructing a pathway model. Methods: Data were collected from the 2018 China Health and Retirement Longitudinal Study (CHRLS). We included 1743 patients with diabetes who were assessed using the CES-D10, which is used to measure depressive symptoms in Chinese older adults. Based on the theory of psychological stress, data were analyzed using SPSS software version 22.0 and MPLUS 8.0. A correlation analysis was used to explore the relationship between the variables and depression scores. A path model was constructed to explore the interrelationships between variables and verify the relationships between variables and depression in patients with diabetes. Results: The prevalence of depression among patients with diabetes was 42.5%. The path analysis results showed that income, diabetes duration, sleep duration, pain distress, self-rated health, and glycemic control directly affected depression, and self-rated health had the largest effect value. With self-rated health and glycemic control as mediator variables, income, diabetes duration, sleep duration, pain distress, glycemic control, and insulin use had indirect effects on depression by influencing self-rated health. Age, frequency of blood glucose monitoring, and exercise glycemic control awareness indirectly affected depression by affecting glycemic control, self-rated health status, and depression. Conclusion: We found that the path analysis model could construct the interaction between the influencing factors and explore the potential interrelationship between the influencing factors and diabetes-related depression. Patients with diabetes must adhere to regular medication, maintain a healthy lifestyle, and have effective glycemic control. Diabetes depression can be effectively prevented by making psychological knowledge publicly available, providing health education, and establishing corresponding for diabetes.

KDM8 epigenetically controls cardiac metabolism to prevent initiation of dilated cardiomyopathy.

Cardiac metabolism is deranged in heart failure, but underlying mechanisms remain unclear. Here, we show that lysine demethylase 8 (Kdm8) maintains an active mitochondrial gene network by repressing Tbx15, thus preventing dilated cardiomyopathy leading to lethal heart failure. Deletion of Kdm8 in mouse cardiomyocytes increased H3K36me2 with activation of Tbx15 and repression of target genes in the NAD+ pathway before dilated cardiomyopathy initiated. NAD+ supplementation prevented dilated cardiomyopathy in Kdm8 mutant mice, and TBX15 overexpression blunted NAD+-activated cardiomyocyte respiration. Furthermore, KDM8 was downregulated in human hearts affected by dilated cardiomyopathy, and higher TBX15 expression defines a subgroup of affected hearts with the strongest downregulation of genes encoding mitochondrial proteins. Thus, KDM8 represses TBX15 to maintain cardiac metabolism. Our results suggest that epigenetic dysregulation of metabolic gene networks initiates myocardium deterioration toward heart failure and could underlie heterogeneity of dilated cardiomyopathy.

Prevalence, antibiotic resistance, and molecular epidemiology of Listeria monocytogenes isolated from imported foods in China during 2018 to 2020.

A total of 1797 imported food samples collected during 2018 to 2020 were investigated for Listeria monocytogenes. Antibiotic susceptibility tests and whole genome sequencing analysis were performed for the obtained isolates. The overall prevalence of L. monocytogenes was 5.62 %; the highest prevalence was observed for pork (13.65 %), followed by fish (6.25 %), sheep casing (6.06 %), chicken (3.61 %), and beef (2.06 %). Geographical differences in prevalence were also observed for pork. Resistance to oxacillin (39.33 %) and clindamycin (16.85 %) was common, whereas resistance rates for other antibiotics were relatively low, ranging from 0 % to 6.74 %. Pork and fish isolates showed resistance to more antibiotics than beef isolates. Tetracycline and chloramphenicol resistance phenotypes strongly correlated with genotypes. The predominant serogroup was 1/2a, 3a, at 44.44 %, while the percentages of three other serogroups were similar and relatively lower, from 17.28 % to 19.75 %. Significant genetic differences were observed among lineage I and II isolates. LIPI-3 was carried by 19.75 % (16/81) of isolates and LIPI-4 by 6.17 % (5/81); all were lineage I. The stress survival island was present in 31.03 % (9/29) of lineage I and 83.02 % (44/53) of lineage II. Benzalkonium chloride tolerance genes were carried by 10.34 % (3/29) of lineage I and 23.08 % (12/52) of lineage II isolates. A total of 25 sequence types (STs) were identified, among which one was novel; ST9 and ST121 were the most prevalent. Disparate distribution of STs among food types was observed, and geographical and food related characteristics were also found for some STs. Hypervirulent STs, such as ST1, ST4 and ST6, belonged to 4b,4e,4e; carried LIPI-3 and/or LIPI-4; and some even were ECI or ECII; while only one carried SSI or BC tolerance genes. In contrast, hypo-virulent STs such as ST9 and ST121 carried SSI and BC tolerance genes, while none had LIPI-3/LIPI-4. Certain STs were detected frequently from a particular food of a particular country for a long time, indicating more attention should be given to these special persistent isolates. These findings are valuable for source tracking, prevention and control of L. monocytogenes in the global food chain.

Identification of Human Global, Tissue and Within-Tissue Cell-Specific Stably Expressed Genes at Single-Cell Resolution.

Stably Expressed Genes (SEGs) are a set of genes with invariant expression. Identification of SEGs, especially among both healthy and diseased tissues, is of clinical relevance to enable more accurate data integration, gene expression comparison and biomarker detection. However, it remains unclear how many global SEGs there are, whether there are development-, tissue- or cell-specific SEGs, and whether diseases can influence their expression. In this research, we systematically investigate human SEGs at single-cell level and observe their development-, tissue- and cell-specificity, and expression stability under various diseased states. A hierarchical strategy is proposed to identify a list of 408 spatial-temporal SEGs. Development-specific SEGs are also identified, with adult tissue-specific SEGs enriched with the function of immune processes and fetal tissue-specific SEGs enriched in RNA splicing activities. Cells of the same type within different tissues tend to show similar SEG composition profiles. Diseases or stresses do not show influence on the expression stableness of SEGs in various tissues. In addition to serving as markers and internal references for data normalization and integration, we examine another possible application of SEGs, i.e., being applied for cell decomposition. The deconvolution model could accurately predict the fractions of major immune cells in multiple independent testing datasets of peripheral blood samples. The study provides a reliable list of human SEGs at the single-cell level, facilitates the understanding on the property of SEGs, and extends their possible applications.

Sensitive and Rapid Detection of Escherichia coli O157:H7 From Beef Samples Based on Recombinase Aided Amplification Assisted CRISPR/Cas12a System.

BACKGROUND: Escherichia coli O157:H7, being the cause of hemorrhagic colitis in humans, is recognized as one of the most dangerous and widespread foodborne pathogens. A highly specific, sensitive, and rapid E. coli O157:H7 detection method needs to be developed since the traditional detection methods are complex, costly, and time-consuming. OBJECTIVE: In this study, a recombinase aided amplification (RAA) assisted CRISPR/Cas12a (RAA-CRISPR/Cas12a) fluorescence platform for specific, sensitive, and rapid nucleic acid detection of E. coli O157:H7 was introduced. METHODS: First, the feasibility (components of CRISPR/Cas12a system) of the developed method was evaluated. Then a total of 34 bacterial strains were used for the specificity test, and gradient dilutions of extracted DNA and bacterial solutions of E. coli O157:H7 were prepared for the sensitivity test. Third, a real-time PCR assay for detection of the specific wzy gene of E. coli O157:H7 (FDA's Bacteriological Analytical Manual) was used for sensitivity comparison. Finally, analysis of RAA-CRISPR/Cas12a detection in spiked and 93 real ground beef samples was carried out. RESULTS: The developed RAA-CRISPR/Cas12a method showed high specificity, and the detection could be completed within 30 min (after 4 h enrichment in spiked ground beef samples). The limit of detection (LOD) of bacterial concentrations and genomic DNA was 5.4 × 102 CFU/mL and 7.5 × 10-4 ng/µL, respectively, which exhibited higher sensitivity than the RAA-gel electrophoresis and RT-PCR methods. Furthermore, it was shown that E. coli O157:H7 in ground beef samples could be positively detected after 4 h enrichment when the initial bacterial inoculum was 9.0 CFU/25 g. The detection results of the RAA-CRISPR/Cas12a method were 100% consistent with those of the RT-PCR and traditional culture-based methods while screening the E. coli O157:H7 from 93 local collected ground beef samples. CONCLUSIONS: The developed RAA-CRISPR/Cas12a method showed high specificity, high sensitivity, and rapid positive detection of E. coli O157:H7 from ground beef samples. HIGHLIGHTS: The RAA-CRISPR/Cas12a system proposed in this study provided an alternative molecular tool for quick, specific, sensitive, and accurate detection of E. coli O157:H7 in foods.

The maltose transporter subunit IICB of the phosphotransferase system: An important factor for biofilm formation of Cronobacter.

Cronobacter is a common food-borne opportunistic pathogen, which is easily to form biofilm and difficult to remove. The regulation mechanism on the biofilm formation of Cronobacter has drawn more and more attention. In here, transcriptomic sequencing of free and biofilm states of Cronobacter was performed, and analyzed to identify the differential gene expression through Gene Ontology (GO) function, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment. Based on sequencing analysis of the results, the malX gene encoding maltose transporter subunit IICB in the phosphotransferase system (PTS) might be involved in the formation of Cronobacter biofilm and thus selected for gene knockout. Hereafter, the changes in biofilm formation ability, extracellular polymer and biofilm-related gene expression of malX gene knockout strains were detected to explore the potential mechanism of malX gene on biofilm formation of Cronobacter. From the result, weaken biofilm formation ability of Cronobacter, decreased extracellular polysaccharide content and down-regulated expression of cellulose-related genes were obtained after knockout of malX gene, which verified our deduction. This study is the first to elucidates the regulation mechanism of the PTS on the biofilm formation of Cronobacter, which lays a foundation for the further prevention and control of food contamination caused by Cronobacter.

Rapid and Electronic Identification and Quantification of Age-Specific Circulating Exosomes via Biologically Activated Graphene Transistors.

Increasing access to modern clinical practices concomitantly extends lifespan, ironically revealing new classes of degenerative and inflammatory diseases of later years. Here, an electronic graphene field-effect transistor (gFET) is reported, termed EV-chip, for label-free, rapid identification and quantification of exosomes (EV) associated with aging through specific surface markers, CD63 and CD151. Studies suggest that blood-derived exosomes carry specific biomolecules that can be used toward diagnostic applications of age and health. However, to observe improvements in patient outcomes, earlier detection at the point-of-care (POC) is required. Unfortunately, conventional techniques and other electronic-based platforms for exosome sensing are burdensome and inept for the POC distinction of aged blood factors. It is shown that EV-chip can quantitatively detect purified exosomes from plasma, with a limit of detection (LOD) of 2 × 104 particles mL-1 and a limit of quantification (LOQ) of 6 × 104 particles mL-1 . The sensitivity and compact electronics of the EV-chip improves upon previously published electronic biosensors, making it ideal for a physician's office or a simple biological laboratory. The sensitivity, selectivity, and portability of the EV-chip demonstrate the potential of the biosensor as a powerful point-of-care diagnostic and prognostic tool for age-related diseases.

Facile construction of a molecularly imprinted polymer-based electrochemical sensor for the detection of milk amyloid A.

A molecularly imprinted electrochemical sensor for the detection of serum amyloid A (MAA) in milk was established for early diagnosis of subclinical mastitis in dairy cows. The electrochemical sensor was initially constructed using a nanocomposite material (reduced graphene oxide/gold nanoparticles, AuNPs@rGO) to modify the working electrode. The template protein, MAA, was then immobilized using pyrrole as the functional monomer to carry out the electropolymerization. Finally, the template protein was removed to form a molecular imprint film with the capability to qualitatively and quantitatively signaling of MAA. Cyclic voltammetry (CV), differential pulse voltammetry (DPV), and scanning electron microscopy (SEM) were used to characterize the modification process of the molecularly imprinted electrochemical sensors. Under optimized conditions, the sensor shows two well-behaved linear relationships in the MAA concentration range 0.01 to 200 ng/mL. A lower detection limit was estimated to be 5 pg/mL (S/N = 3). Other parameters including the selectivity, reproducibility (RSD 3.2%), and recovery rate (96.1-103%) are all satisfactory. Compared with the traditional methods, detection of MAA to determine the subclinical mastitis of dairy cows can efficiently be diagnosed and hence prevent an outbreak of dairy cow mastitis. The electrochemical sensor can detect MAA more rapidly, sensitively, and inexpensively than the ELISA-based MAA detection. These advantages indicate that the method is promising for early diagnosis of dairy cows.