Multiphoton Ionization/Dissociation of Molecular Sulfur S2 in the UV Region.

The multiphoton ionization/dissociation dynamics of molecular sulfur (S2) in the ultraviolet range of 205-300 nm is studied using velocity map ion imaging (VMI). In this one-color experiment, molecular sulfur (S2) is generated in a pulsed discharge and then photodissociated by UV radiation. At the three-photon level, superexcited states are accessed via two different resonant states: the B3Σu- (v' = 8-11) valence states at the one-photon level and a Rydberg state at the two-photon level. Among the decay processes of these superexcited states, dissociation to electronically excited S atoms is dominant as compared to autoionization to ionic states S2+ (X2Πg) at wavelengths λ < 288 nm. The anisotropy parameter extracted from these images reflects the parallel character of these electronic transitions. In contrast, autoionization is found to be particularly efficient at S(1D) and S(1S) detection wavelengths around 288 nm. Information obtained from the kinetic energy distributions of S atoms has revealed the existence of vibrationally excited S2+ (X2Πg (v+ > 11)) that dissociates to ionic products following one-photon absorption. This work also reveals many interesting features of S2 photodynamics compared to those of electronically analogous O2.

Radiofrequency catheter ablation for re-do procedure after single-shot pulmonary vein isolation with pulsed field ablation for paroxysmal atrial fibrillation: case report.

Background: Catheter ablation is frequently used to manage recurrent atrial fibrillation (AF) resistant to drug therapy, with pulmonary vein isolation (PVI) as a key tactic. Pulsed field ablation (PFA) has emerged as an innovative technology for PVI but poses challenges for redo procedures. Case presentation: We report on a 73-year-old female patient who experienced recurrent AF after initial successful PVI using a novel PFA technology and subsequently underwent radiofrequency catheter ablation during a repeat intervention. The reconnection of pulmonary veins was discovered primarily in the anterior region of the right superior PV and the superior portion of the left superior PV. An anatomically-based segmental approach and larger circumferential PVI, followed by additional linear ablations at non-PV trigger sites, proved decisive in preventing further recurrence of atrial tachycardia. Conclusion: While PFA exhibits promise as a secure and efficient modality for PVI, it necessitates excellent contact quality to ensure lasting results. For patients experiencing AF recurrences post-PFI, expanded strategies incorporating both comprehensive PVI and linear ablations at targeted non-PV sites might enhance treatment outcomes.

Self-assembled bifunctional nanoflower-enabled CRISPR/Cas biosensing platform for dual-readout detection of Salmonella enterica.

Sensitive detection and point-of-care test of bacterial pathogens is of great significance in safeguarding the public health worldwide. Inspired by the characteristics of horseradish peroxidase (HRP), we synthesized a hybrid nanoflower with peroxidase-like activity via a three-component self-assembled strategy. Interestingly, the prepared nanozyme not only could act as an alternative to HRP for colorimetric biosensing, but also function as a unique signal probe that could be recognized by a pregnancy test strip. By combining the bifunctional properties of hybrid nanoflower, isothermal amplification of LAMP, and the specific recognition and non-specific cleavage properties of CRISPR/Cas12a system, the dual-readout CRISPR/Cas12a biosensor was developed for sensitive and rapid detection of Salmonella enterica. Moreover, this platform in the detection of Salmonella enterica had limits of detection of 1 cfu/mL (colorimetric assay) in the linear range of 101-108 cfu/mL and 102 cfu/mL (lateral flow assay) in the linear range of 102-108 cfu/mL, respectively. Furthermore, the developed biosensor exhibited good recoveries in the spiked samples (lake water and milk) with varying concentrations of Salmonella enterica. This work provides new insights for the design of multifunctional nanozyme and the development of innovative dual-readout CRISPR/Cas system-based biosensing platform for the detection of pathogens.

Photoionization cross sections measurements of the excited states of lutetium and ytterbium in the near threshold region.

In this work, the threshold photoionization cross sections from the excited states of lutetium and ytterbium atoms were investigated by the laser pump-probe scheme under the condition of saturated resonant excitation. We obtained the resonance enhanced multiphoton ionization spectra of the lutetium and ytterbium atoms of the lanthanide metals in the range of 307.50-312.50 nm and 265.00-269.00 nm, respectively; the photoionization cross sections of the 5d6s(1D)6p(2D05/2) and 5d6s(3D)6p(2P01/2) states of lutetium and the 4f13(2F0)5d6s2(J = 1) states of ytterbium above threshold regions (0.4-1.6 eV) were measured, and measured values ranged from 2.3 ± 0.2 to 17.7 ± 1.5 Mb.

CodLncScape Provides a Self-Enriching Framework for the Systematic Collection and Exploration of Coding LncRNAs.

Recent studies have revealed that numerous lncRNAs can translate proteins under specific conditions, performing diverse biological functions, thus termed coding lncRNAs. Their comprehensive landscape, however, remains elusive due to this field's preliminary and dispersed nature. This study introduces codLncScape, a framework for coding lncRNA exploration consisting of codLncDB, codLncFlow, codLncWeb, and codLncNLP. Specifically, it contains a manually compiled knowledge base, codLncDB, encompassing 353 coding lncRNA entries validated by experiments. Building upon codLncDB, codLncFlow investigates the expression characteristics of these lncRNAs and their diagnostic potential in the pan-cancer context, alongside their association with spermatogenesis. Furthermore, codLncWeb emerges as a platform for storing, browsing, and accessing knowledge concerning coding lncRNAs within various programming environments. Finally, codLncNLP serves as a knowledge-mining tool to enhance the timely content inclusion and updates within codLncDB. In summary, this study offers a well-functioning, content-rich ecosystem for coding lncRNA research, aiming to accelerate systematic studies in this field.

Colorimetric biosensor based on aptamer recognition-induced multi-DNA release and peroxidase-mimicking three-way junction DNA-Ag/PtNCs for the detection of Salmonella typhimurium.

Salmonella typhimurium, as a major foodborne pathogen, poses a serious threat to public health safety worldwide. Here, we present a colorimetric biosensor based on aptamer recognition-induced multi-DNA release and peroxidase-mimicking three-way junction DNA-silver/platinum bimetallic nanoclusters (3WJ/DNA-Ag/PtNCs) for the detection of S. typhimurium. In this method, S. typhimurium specifically binds to the aptamer and releases multiple cDNAs to form the three-way junction DNA structure and synthesize silver/platinum bimetallic nanoclusters, which induces signaling changes. Interestingly and importantly, the use of 3WJ/DNA as the template for synthesizing Ag/PtNCs gives the method an extremely low background signal. Under the optimal conditions, the constructed biosensor had a linear response range of 2.6 × 102-2.6 × 106 CFU/mL and a detection limit of 2.6 × 102 CFU/mL for the detection of S. typhimurium. In addition, the proposed method can effectively detect S. typhimurium in milk.

Patterns of unhealthy lifestyle and their associations with depressive and anxiety symptoms among Chinese young adults: A latent class analysis.

BACKGROUND: There is little evidence on the association between patterns of unhealthy lifestyle and mental health among young adults. METHOD: This study included a total of 28,978 young adults aged 18 to 44 years old in Guangdong province in south China, which was conducted from September to December in 2022. We used latent class analysis to classify the patterns of unhealthy lifestyle among young adults and used multiple logistic regression to explore their associations with depressive and anxiety symptoms. RESULT: The weighted prevalence of depressive and anxiety symptoms were 28.0 % and 19.5 %, respectively. The cumulative effect of unhealthy lifestyles on depressive and anxiety symptoms was significant. Five patterns of unhealthy lifestyle were classified. Compared to the relatively healthy lifestyle class, the class with more unhealthy lifestyles (OR = 6.54, 95 % CI: 5.70-7.51) and insufficient sleep (OR = 6.16, 95 % CI: 4.92-7.70) had higher risk for depressive and anxiety symptoms. Meaningfully, having adequate mental health literacy could reduce the risk of depressive and anxiety symptoms from unhealthy lifestyle by half. LIMITATIONS: The cross-section design study limited causal inferences, and the self-report information may lead to recall bias. CONCLUSIONS: Unhealthy lifestyles have a negative impact on depressive and anxiety symptoms through independent, cumulative and combined effects, and they could be interrelated. Unhealthy lifestyle patterns differed in younger population by socio-demographic characteristics and mental health literacy. Health-care professionals and policymakers may provide programs to intervene multiple unhealthy lifestyles and improve mental health literacy by integrating healthy lifestyle education to promote youngers' mental health.

The Immunomodulatory Effects of A2 ß-Casein on Immunosuppressed Mice by Regulating Immune Responses and the Gut Microbiota.

The aim of this study was to investigate the immunomodulatory effects of A2 ß-casein (ß-CN) in cyclophosphamide-induced immunosuppressed BALB/c mice. Experiments conducted in vitro revealed that A2 ß-CN digestive products have potent immunostimulatory activities. Animal studies demonstrated that A2 ß-CN improved the immunological organ index reduction trend caused by cyclophosphamide, reduced the pathological damage to the spleen tissue in immunosuppressed mice, increased the release of IL-17A, IgG, and IgA, and reduced the production of IL-4. By regulating the relative abundance of advantageous bacteria like Oscillospira, Lactobacillus, and Bifidobacteria and harmful bacteria like Coprococcus and Desulfovibrionaceae, A2 ß-CN improved gut microbiota disorders in immunosuppressed mice. Moreover, A2 ß-CN promoted the production of short-chain fatty acids and increased the diversity of the gut microbiota. Therefore, ingestion of A2 ß-CN is beneficial to the host's immune system and gut health. These findings provide insights for the future application of A2 ß-CN-related dairy products.

Osr1-mediated mesothelial transition of liver mesenchymal cells exacerbates fibrotic liver damage.

In chronic liver diseases, hepatic stellate cells (HSCs) are induced to form the myofibroblasts responsible for scar formation, leading to liver fibrosis and cirrhosis. Here, single-cell RNA sequencing with in vivo lineage tracing in nonalcoholic steatohepatitis (NASH) model mice reveals a subpopulation of HSCs transitioning back to a state resembling their developmental precursors, mesothelial cells (MCs), after liver injury. These damage-associated intermediates between HSCs and MCs (DIHMs) can be traced with a dual recombinase system by labeling Krt19-expressing cells within prelabeled Pdgfrb+ HSCs, and DIHMs highly express inflammation- and fibrosis-associated genes. Cre and Dre-inducible depletion of DIHMs by administering diphtheria toxin reduces liver fibrosis and alleviates liver damage in NASH model mice. Importantly, knockdown of Osr1, a zinc finger transcription factor of the OSR gene family, can block DIHM induction in vitro. Conditional knockout Osr1 in Pdgfrb-expressing mesenchymal cells in NASH model mice can reduce liver fibrosis in vivo. Our study collectively uncovers an injury-induced developmental reversion process wherein HSCs undergo what we call a mesenchymal-to-mesothelial transition, which can be targeted to develop interventions to treat chronic liver diseases.

Optical nanosensors based on noble metal nanoclusters for detecting food contaminants: A review.

Food contaminants present a significant threat to public health. In response to escalating global concerns regarding food safety, there is a growing demand for straightforward, rapid, and sensitive detection technologies. Noble metal nanoclusters (NMNCs) have garnered considerable attention due to their superior attributes compared to other optical materials. These attributes include high catalytic activity, excellent biocompatibility, and outstanding photoluminescence properties. These features render NMNCs promising candidates for crafting nanosensors for food contaminant detection, offering the potential for the development of uncomplicated, swift, sensitive, user-friendly, and cost-effective detection approaches. This review investigates optical nanosensors based on NMNCs, including the synthesis methodologies of NMNCs, sensing strategies, and their applications in detecting food contaminants. Furthermore, it involves a comparative assessment of the applications of NMNCs in optical sensing and their performance. Ultimately, this paper imparts fresh perspectives on the forthcoming challenges. Hitherto, optical (particularly fluorescent) nanosensors founded on NMNCs have demonstrated exceptional sensing capabilities in the realm of food contaminant detection. To enhance sensing performance, future research should prioritize atomically precise NMNCs synthesis, augmentation of catalytic activity and optical properties, development of high-throughput and multimode sensing, integration of NMNCs with microfluidic devices, and the optimization of NMNCs storage, shelf life, and transportation conditions.

Effects of different reducing carbohydrate types on the physicochemical characteristics of infant formula food stored for special medical purposes.

The formula of food for special medical purpose has a direct impact on physicochemical stability, especially in hot climes and high temperature transport storage environments. An accelerated test (50 °C for 7 weeks) was used to analyze the mechanism of the physicochemical instability of formula A with lactose and maltodextrin, and formula B with maltodextrin. Deep dents and wrinkles were observed on the surface of the formula B, and more fat globules covered the surface of formula A particles after storage for a long time. Significantly higher amounts of furosine and Nε-carboxymethl-l-lysine (CML) were formed and the loss of available lysine was greater in formula A than in formula B. No significant difference was observed in lipid oxidation indicators between the two formulas. The results of this research demonstrated lactose was more active than maltodextrin and led to physicochemical instability.

Recent advances in the bovine ß-casein gene mutants on functional characteristics and nutritional health of dairy products: Status, challenges, and prospects.

ß-casein is the second most abundant form of casein in milk. Changes in amino acid sequence at specific positions in the primary structure of ß-casein in milk will produce gene mutations that affect the physicochemical properties of dairy products and the hydrolysis site of digestive enzymes. The screening method of ß-casein allele frequency detection in dairy products also has attracted the extensive attention of scientists and farmers. The A1 and A2 ß-casein is the two usual mutation types, distinguished by histidine and proline at position 67 in the peptide chain. This paper summarizes the effects of A1 and A2 ß-casein on the physicochemical properties of dairy products and evaluates the effects on human health, and the genotyping methods were also concluded. Impressively, this review presents possible future opportunities and challenges for the promising field of A2 ß-casein, providing a valuable reference for the development of the functional dairy market.

G-triplex/hemin DNAzyme mediated colorimetric aptasensor for Escherichia coli O157:H7 detection based on exonuclease III-assisted amplification and aptamers-functionalized magnetic beads.

Escherichia coli O157: H7 (E. coli O157: H7) is one of the most common foodborne pathogens and is widespread in food and the environment. Thus, it is significant for rapidly detecting E. coli O157: H7. In this study, a colorimetric aptasensor based on aptamer-functionalized magnetic beads, exonuclease III (Exo III), and G-triplex/hemin was proposed for the detection of E. coli O157: H7. The functional hairpin HP was designed in the system, which includes two parts of a stem containing the G-triplex sequence and a tail complementary to cDNA. E. coli O157: H7 competed to bind the aptamer (Apt) in the Apt-cDNA complex to obtain cDNA. The cDNA then bound to the tail of HP to trigger Exo III digestion and release the single-stranded DNA containing the G-triplex sequence. G-triplex/hemin DNAzyme could catalyze TMB to produce visible color changes and detectable absorbance signals in the presence of H2O2. Based on the optimal conditions, E. coli O157: H7 could be detected down to 1.3 × 103 CFU/mL, with a wide linear range from 1.3 × 103 to 1.3 × 107 CFU/mL. This method had a distinguished ability to non-target bacteria, which showed good specificity. In addition, the system was successfully applied to detect E. coli O157: H7 in milk samples.

Casein hydrolysate's effects on the fermentation properties, texture, and chemical characteristics and the bacterial microbiota of fermented glutinous rice dough.

To investigate how casein hydrolysate affected the physicochemical properties and microbiological diversity of the glutinous rice dough (natural fermentation and yeast fermentation), we analyzed its fermentation properties, carbohydrate, protein degradation, texture, and bacterial composition. According to the findings, casein hydrolysate increased the total LAB number, as well as organic acid content, in naturally fermented and yeast fermented glutinous rice dough by 3.59 and 8.19%, respectively, and reduced the fermentation time by at least 2 h. Meanwhile, casein hydrolysate enhanced the content of reducing sugars by 4.46 and 13.53% and increased protease activity by 29.9 and 27.7%. In addition, casein hydrolysate accelerated protein breakdown and regulated the hardness of the dough to improve the texture. Casein hydrolysate enriched the bacterial richness and diversity of dough. After adding casein hydrolysate, it promoted the growth of Pediococcus, Enterococcus, Lactobacillus, and Streptococcus. According to the Spearman correlation analysis, environmental factors (pH, lactic acid, acetic acid, reducing sugar content, and protease activity) exhibited the major driver for the abundance of bacterial species (Spearman correlation coefficient: -0.71 to 0.78). As a potential food additive, casein hydrolysate can improve the fermentation and quality of glutinous rice dough, increase consumer acceptance of cereal foods, and give consumers healthier options.

Detection of trace phosphorus in water by plasma amplification laser-induced breakdown spectroscopy.

For monitoring the extent of eutrophication in water, phosphorus (P) was detected by laser-induced breakdown spectroscopy (LIBS). A plasma amplification method was proposed and the filtered aerosol was guided to interact with the collinear laser in conjunction with a nebulizer, cyclonic spray chamber, and quartz tube. With this method, the length of the plasma was amplified from 5.27∼8.73 to 17.58 mm. Moreover, the limit of detection (LoD) values of P in water improved from 6.13∼17.75 to 3.60 ppm. Furthermore, the average relative error (REAV) values reduced from 10.23∼23.84 to 6.17%. The root mean square error of cross-validation (RMSECV) values decreased from 16.68∼64.29 to 3.24 ppm. This demonstrated that plasma amplification LIBS could improve the quantitative analysis performance of LIBS detection of trace phosphorus in water.

Assessment of Candidate Reference Genes for Gene Expression Studies Using RT-qPCR in Colletotrichum fructicola from Litchi.

Litchi (Litchi chinensis Sonn.) is a tropical fruit originating from southern China that is currently cultivated in subtropical and tropical regions worldwide. Litchi anthracnose, caused by Colletotrichum fructicola, a dominant species of Colletotrichum spp., is an important disease of litchi that damages the fruits in fields and in post-harvest storage. Real-time quantitative PCR (RT-qPCR) is a common technique with which to detect the expression of and function of target genes quickly and precisely, and stable reference genes are crucial. However, there is no comprehensive information on suitable reference genes of C. fructicola present. Here, we designed eight candidate genes (GAPDH, α-tubulin, 18S, ß-tubulin, EF1a, TATA, RPS5, and EF3) using RefFinder software (programs: geNorm, ΔCt, BestKeeper, and NormFinder) to investigate their reliability in the detection of C. fructicola under five different treatments (fungal development stage, temperature, UV, culture medium, and fungicide). The results showed the optimal reference genes under different conditions: EF1a and α-tubulin for developmental stage; α-tubulin and ß-tubulin for temperature; α-tubulin and RPS5 for UV treatment; RPS5 and α-tubulin for culture medium; α-tubulin, GAPDH, and TATA for fungicide treatments. The corresponding expression patterns of HSP70 (Heat shock protein 70) were significantly different when the most and the least stable reference genes were selected when treated under different conditions. Our study provides the first detailed list of optimal reference genes for the analysis of gene expression in C. fructicola via RT-qPCR, which should be useful for future functional studies of target genes in C. fructicola.

Real-world tobacco cessation practice in China: findings from the prospective, nationwide multicenter China National Tobacco Cessation Cohort Study (CNTCCS).

Background: Tobacco cessation is proven to be the most effective and cost-effective strategy for smokers to reduce their risk of smoking-related disease and premature death. Providing effective, efficient, safe, and patient-centred tobacco cessation treatment to reach those who need them is a significant challenge. To date, only a few nationwide studies in China have assessed the overall clinical care practice and treatment outcome of tobacco cessation. Methods: This a prospective, nationwide, multicenter, cohort study covering all Eastern China, Northwest China, Central China, North China, Southwest China, Northeast China, and South China. Participants who were current smokers aged 18-85 years attending clinic for smoking cessation were included. All the participants were treated with 3-month cessation treatment and followed up for 3 months. Data were collected prospectively using online system. The primary outcome was 7-day point abstinence rate at 24 weeks, validated biochemically by an expired carbon monoxide level of less than 10 ppm. The participants lost to follow-up or not providing validation were included as non-abstainers. Findings: A representative sample of 3557 participants were recruited and 2943 participants were included into this analysis. These participants had mean age of 53.05 years, and 94.8% were males, with 75.8% showing symptoms of tobacco dependence. A total of 965 (32.8%) participants were treated with Bupropion + behavioural counselling, followed by 935 (31.8%) with behavioural counselling, 778 (26.4%) with Varenicline + behavioural counselling, 135 (4.6%) with alternative treatments + behavioural counselling, and 130 (4.4%) with nicotine replacement therapy (NRT) + behavioural counselling. After 3-month treatment and 3-month follow-up, 21.74% of the participants quit smoking at 24 weeks. In the multivariable-adjusted analyses, quitting smoking was significantly associated with female, higher socioeconomic status, poor health condition, different treatment received, and less smoking intensity. The tobacco cessation treatment varied widely across different areas of China. In particular, the areas with higher usage of cessation medication were associated with better cessation treatment outcome. Interpretation: The CNTCCS is the first large-scale nationwide cohort study of smoking cessation in China. Rich data collected from this prospective cohort study provided the opportunity to evaluate the clinical practice of tobacco cessation treatment in China. Funding: Chinese Academy of Medical Sciences (CAMS) Initiative for Innovative Medicine (CAMS 2021-I2M-1-010), Heilongjiang Provincial Science and Technology Key Program (2022ZXJ03C02), and National Key R&D Program of China (grant no. 2017YFC1309400).

Elevated expression of CXCL3 in colon cancer promotes malignant behaviors of tumor cells in an ERK-dependent manner.

BACKGROUND: CXC chemokine ligand 3 (CXCL3) is a member of CXC-type chemokine family that is identified as a major regulator in immune and inflammation responses. Recently, numerous evidence indicated that CXCL3 is broadly expressed in various human tumor types, and it is also known to play a critical role in mediating tumor development and progression. However, the expression profile of CXCL3 and the exact molecular mechanism behind the role of CXCL3 in colon adenocarcinoma (COAD) has not been fully elucidated. METHODS: The expression and clinical significance of CXCL3 mRNA and protein in the tissues from COAD patients were estimated using bioinformatics and immunohistochemistry assays. The expression and roles of exogenous administration or overexpression of CXCL3 in HT-29 and SW480 COAD cells were determined using enzyme-linked immunosorbent assay(ELISA), Cell Counting Kit-8 (CCK-8) and Transwell assays. Mechanically, CXCL3-induced malignant behaviors were elucidated using western blotting assay and extracellular signal-regulated protein kinase 1/2 (ERk1/2) inhibitor PD98059. RESULTS: The cancer genome atlas (TCGA)-COAD data analysis revealed that CXCL3 mRNA is highly expressed and has high clinical diagnostic accuracy in COAD. Increased expression of CXCL3 mRNA was associated with patient's clinical stage, race, gender, age, histological subtype, nodal mestastasis and tumor protein 53 (TP53) mutation status. Similarly, immunohistochemistry assay also exhibited that CXCL3 protein in COAD tissues was significantly up-regulated. Gene expression associated assay implied that CXC chemokine ligand 1 (CXCL1) and CXC chemokine ligand 2 (CXCL2) were markedly correlated with CXCL3 in COAD. Protein-protein interaction (PPI) analysis revealed that cyclin B1 (CCNB1), mitotic arrest deficient 2 like 1 (MAD2L1), H2A family member Z (H2AFZ) and CXCL2 may be the important protein molecules involved in CXCL3-related tumor biology. Gene set enrichment analysis (GSEA) analysis revealed that CXCL3 was mainly enriched in the cell cycle, DNA replication, NOD-like receptors, NOTCH and transforming growth factor-ß (TGF-ß) Signal pathways. In vitro, exogenous administration or overexpression of CXCL3 resulted in increased malignant behaviors of HT-29 and SW480 cells, and down-regulation of CXCL3 expression inhibited the malignant behaviors of these tumor cells. In addition, overexpression of CXCL3 affected the expression of genes related to extracellular signal regulated kinase (ERK) pathway, including ERK1/2, p-ERK, B-cell lymphoma-2 (Bcl-2), Bcl-2-associated X protein (Bax) and Cyclin D1. Finally, CXCL3-induced malignant behaviors in HT-29 and SW480 cells were obviously attenuated following treatment with ERK inhibitor PD98059. CONCLUSION: CXCL3 is upregulated in COAD and plays a crucial role in the control of malignant behaviors of tumor cells, which indicated its involvement in the pathogenesis of COAD.

Whole-transcriptome analysis after the acquisition of antibiotic resistance of Cronobacter sakazakii: Mechanisms of antibiotic resistance and virulence changes.

The emergence of antibiotic-resistant bacteria led to the misuse of antibiotics, resulting in the emergence of more resistant bacteria and continuous improvement in their resistance ability. Cronobacter sakazakii (C. sakazakii) has been considered a pathogen that harms infants. Incidents of C. sakazakii contamination have continued globally, several studies have indicated that C. sakazakii is increasingly resistant to antibiotics. A few studies have explored the mechanism of antibiotic resistance in C. sakazakii, and some have examined the antibiotic resistance and changes in virulence levels. We aimed to investigate the antibiotic resistance mechanism and virulence differences in C. sakazakii. The level of virulence factors of C. sakazakii was modified after induction by antibiotics compared with the antibiotic-sensitive strains, and the XS001-Ofl group had the strongest capacity to produce enterotoxin (85.18 pg/mL) and hemolysin (1.47 ng/mL). The biofilm formation capacity after induction significantly improved. The number of bases and mapped reads in all groups accounted for more than 55 % and 70 %, as detected by transcriptomic analysis. The resistance mechanism of different antibiotics was more common in efflux pumps, cationic antimicrobial peptides, and biofilm formation pathways. The level of antibiotic resistance mainly affected the expression of virulence genes associated with flagella assembly and synthesis.

Co-culture of Cronobacter sakazakii and Staphylococcus aureus: Explore the influence of mixed biofilm formation and regulation of Cronobacter sakazakii biofilm formation genes.

Bacterial biofilm is a protective matrix composed of metabolites secreted by bacteria that envelop bacteria. By forming a biofilm, bacteria can considerably improve their environmental tolerance. In food-related processing environment, different types of microorganisms are often present in biofilms. The main contaminating strain in the powdered infant formula (PIF) processing environment, Cronobacter sakazakii and Staphylococcus aureus continues to pollute the PIF processing environment after biofilm production. This study selected Cronobacter sakazakii with a weak biofilm-forming ability as one of the test organisms. The coexistence of Cronobacter sakazakii and Staphylococcus aureus on the surface of production equipment was simulated to analyze the interaction. Biofilm formation in the co-culture group was significantly higher than the others. In-depth study of the effect of Staphylococcus aureus on the biofilm formation genes of Cronobacter sakazakii. Results show two bacteria can coexist on the surface of a metal device, forming a more compact hybrid biofilm structure. Under co-culture conditions, S. aureus increased bcsA and fliD expression in Cronobacter sakazakii, whereas decreased bcsC expression. Signaling molecules produced by Staphylococcus aureus (Autoinducer 2) significantly promoted the biofilm formation of Cronobacter sakazakii at the concentration of 0-500 ng/mL (0.099-0.177) and up-regulated the expression of bcsA, filD and flhD genes.