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Enteric pathogens such as Salmonella enterica serovar Typhimurium experience spatial and temporal changes to the metabolic landscape throughout infection. Host reactive oxygen and nitrogen species non-enzymatically convert monosaccharides to alpha hydroxy acids, including L-tartrate. Salmonella utilizes L-tartrate early during infection to support fumarate respiration, while L-tartrate utilization ceases at later time points due to the increased availability of exogenous electron acceptors such as tetrathionate, nitrate, and oxygen. It remains unknown how Salmonella regulates its gene expression to metabolically adapt to changing nutritional environments. Here, we investigated how the transcriptional regulation for L-tartrate metabolism in Salmonella is influenced by infection-relevant cues. L-tartrate induces the transcription of ttdBAU, genes involved in L-tartrate utilization. L-tartrate metabolism is negatively regulated by two previously uncharacterized transcriptional regulators TtdV (STM3357) and TtdW (STM3358), and both TtdV and TtdW are required for the sensing of L-tartrate. The electron acceptors nitrate, tetrathionate, and oxygen repress ttdBAU transcription via the two-component system ArcAB. Furthermore, the regulation of L-tartrate metabolism is required for optimal fitness in a mouse model of Salmonella-induced colitis. TtdV, TtdW, and ArcAB allow for the integration of two cues, i.e., substrate availability and availability of exogenous electron acceptors, to control L-tartrate metabolism. Our findings provide novel insights into how Salmonella prioritizes the utilization of different electron acceptors for respiration as it experiences transitional nutrient availability throughout infection.ImportanceBacterial pathogens must adapt their gene expression profiles to cope with diverse environments encountered during infection. This coordinated process is carried out by the integration of cues that the pathogen senses to fine-tune gene expression in a spatiotemporal manner. Many studies have elucidated the regulatory mechanisms of how Salmonella sense metabolites in the gut to activate or repress its virulence program; however, our understanding of how Salmonella coordinates its gene expression to maximize the utilization of carbon and energy sources found in transitional nutrient niches is not well understood. In this study, we discovered how Salmonella integrates two infection-relevant cues, substrate availability and exogenous electron acceptors, to control L-tartrate metabolism. From our experiments, we propose a model for how L-tartrate metabolism is regulated in response to different metabolic cues in addition to characterizing two previously unknown transcriptional regulators. This study expands our understanding of how microbes combine metabolic cues to enhance fitness during infection.

Acute gastrointestinal infection with intracellular pathogens like Salmonella Typhimurium triggers the release of the proinflammatory cytokine interleukin 1β (IL-1β). However, the role of IL-1β in intestinal defense against Salmonella remains unclear. Here, we show that IL-1β production is detrimental during Salmonella infection. Mice lacking IL-1β (IL-1β -/-) failed to recruit neutrophils to the gut during infection, which reduced tissue damage and prevented depletion of short-chain fatty acid (SCFA)-producing commensals. Changes in epithelial cell metabolism that typically support pathogen expansion, such as switching energy production from fatty acid oxidation to fermentation, were absent in infected IL-1β -/- mice which inhibited Salmonella expansion. Additionally, we found that IL-1β induces expression of complement anaphylatoxins and suppresses the complement-inactivator carboxypeptidase N (CPN1). Disrupting this process via IL-1β loss prevented mortality in Salmonella-infected IL-1β -/- mice. Finally, we found that IL-1β expression correlates with expression of the complement receptor in patients suffering from sepsis, but not uninfected patients and healthy individuals. Thus, Salmonella exploits IL-1β signaling to outcompete commensal microbes and establish gut colonization. Moreover, our findings identify the intersection of IL-1β signaling and the complement system as key host factors involved in controlling mortality during invasive Salmonellosis.

Genetic screening of pools of mutants can reveal genetic determinants involved in complex biological interactions, processes, and systems. We previously constructed two single-gene deletion resources for Salmonella enterica serovar Typhimurium 14028s in which kanamycin (KanR) and chloramphenicol (CamR) cassettes were used to replace non-essential genes. We have now used lambda-red recombination to convert the antibiotic cassettes in these resources into a tetracycline-resistant (TetR) version where each mutant contains a different 21-base barcode flanked by Illumina Read1 and Read2 primer sequences. A motility assay of a pool of the entire library, followed by a single-tube processing of the bacterial pellet, PCR, and sequencing, was used to verify the performance of the barcoded TetR collection. The new resource is useful for experiments with defined subsets of barcoded mutant strains where biological bottlenecks preclude high numbers of founder bacteria, such as in animal infections. The TetR version of the library will also facilitate the construction of triple mutants by transduction. The resource of 6197 mutants covering 3490 genes is deposited at Biological and Emerging Infections Resources (beiresources.org).

Customer requests are addressed to safe products that best express their characteristics of "naturalness" and "freshness" for their entire shelf life; therefore, scientific research has been exploring the use of "non-thermal technologies". Thermosonication using low-frequency focused ultrasound determines bacterial inactivation through the phenomenon of "cavitation", guaranteeing high-quality standards of safety, nutrition, and freshness of the products. The present work aims to evaluate the effectiveness of the inactivation of Salmonella typhimurium in culture broth by low-frequency focused thermosonication with two different operational parameters: sublethal temperature (40°C, 50°C) and treatment time (5, 10, and 15 minutes). Treatment determined a bacterial load reduction compared to the negative control (untreated inoculum), which was statistically significant at the t-test (p<0.05). Average decreases of 1.5 log and 3.5 CFU/mL were observed, respectively, after treatment and after 24 hours of storage at +4°C. Treatment at 50°C for 15 minutes was the most effective (average value: 3.06 log CFU/mL; minimum value: 2.13 log CFU/mL; maximum value: 4.59 log CFU/mL). However, strains have shown markable variability: one of them even showed an increase in the microbial load 24 hours after treatment at 40°C for 5 minutes (-0.20 log CFU/mL); however, the same treatment showed a reduction of bacterial charge in all the other strains (average value: 1.05 log CFU/mL; minimum value: -0.20 log CFU/mL; maximum value: 2.28 log CFU/mL). This study poses numerous perspectives on the use of low-frequency focused thermosonication treatment in the food industry as a sustainable and safe alternative to classic thermal treatments. [ABSTRACT FROM AUTHOR]

• Obliquumol had an LD 50 >2000 mg/kg since there were no mortalities after 14 days. • At the highest dose of obliquumol, the mass, behaviour and food intake of the mice were not affected. • Gross necropsy and histopathological analysis on organs indicated hardly any effects of obliquumol. • P. obliquum leaf extracts, fractions (hexane, chloroform and 30 % H 2 O in MeOH) and isolated compounds (obliquumol and a mixture of lupeol and β-amyrin) had no genotoxic activity against the salmonella typhimurium strains (TA 100, TA 100, and TA 102). Obliquumol (12- O -acetylptaeroxylinol) isolated from Ptaeroxylon obliquum leaves has excellent antifungal activity and low cellular toxicity. As a next step in the potential development of a framework antifungal product, the present work investigated the acute animal toxicity of obliquumol according to OECD 423 guidelines. Furthermore, the genotoxicity of P. obliquum acetone leaf extracts, fractions (hexane, chloroform and 30 % H 2 O in MeOH) and isolated compounds (obliquumol and a mixture of lupeol and β-amyrin) was determined using Ames test.. A single dose of obliquumol was orally administered to mice at levels of 50, 300 and 2000 mg/kg and observed for 14 days. The three S. typhimurium tester strains TA 98, TA 100 and TA 102 were used without metabolic activation to determine the genotoxicity. Even at the highest dose of obliquumol, the mass, behaviour and food intake of the animals were not affected. Gross necropsy and histopathological analysis on organs indicated hardly any effects. No samples had genotoxic activity against the S. typhimurium strains tested. Obliquumol had an LD 50 >2000 mg/kg since there were no mortalities after 14 days. This encourages the possible development of a new class of antifungal compounds from the obliquumol framework. [Display omitted] [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. The use of essential oils (EO) has attracted interest in the food industry because of their wide range of beneficial properties. In this study, a new functional yogurt was developed using 2 EO, marjoram and geranium, at 3 different concentrations (0.2%, 0.4%, and 0.6% vol/vol). The physicochemical properties, including syneresis, viscosity, pH, and chemical composition; bioactivities, including antioxidant activity, anticancer and antibacterial effects, total phenolic content (TPC), and total flavonoid content (TFC); and sensory characteristics of the developed yogurt were evaluated. The findings indicated that the yogurts fortified with 0.6% marjoram or geranium exhibited higher viscosity and lower syneresis compared with other treatments. The yogurt supplemented with 0.6% marjoram displayed significant antibacterial activity against Listeria monocytogenes, Staphylococcus aureus, Salmonella typhimurium , and Escherichia coli. In addition, the yogurt enriched with geranium and marjoram oils at a concentration of 0.6% had notably significant (P < 0.05) higher TFC levels compared with the control sample and other concentrations. In the same context, in terms of TPC, yogurt supplemented with 0.6% marjoram displayed significantly (P < 0.05) elevated levels in comparison to the other samples tested. Yogurt enriched with marjoram oil exhibited noteworthy antioxidant activity, followed by geranium oil, compared with the control samples. The yogurt supplemented with 0.6% marjoram demonstrated strong radical scavenging activity, and the yogurt fortified with 0.6% geranium showed higher anticancer activity against HepG2 human liver carcinoma cells and oxidative stress enzyme activities. Among the various concentrations of EO tested, the yogurts fortified with 0.6% marjoram or geranium EO exhibited the most favorable outcomes, followed by 0.4% marjoram or geranium. To summarize, geranium and marjoram EO can be used as a potential nutritious ingredient and as a natural preservative for milk and related products. [Display omitted] [ABSTRACT FROM AUTHOR]

BACKGROUND: Folate is crucial for maintaining health, but humans are unable to synthesize folate and need to obtain it from food. Lactiplantibacillus plantarum can produce the necessary vitamin B for the human body, including folate. Whole genome sequencing technology can clarify the physiological characteristics of folate production in Lactiplantibacillus plantarum. In order to explore new Lactiplantibacillus plantarum that produce folate, the folate production and probiotic characteristics of Lactiplantibacillus plantarum ZFM55 isolated from infant feces were investigated, and whole genome sequencing was performed. RESULTS: The folate synthesis ability of Lactiplantibacillus plantarum ZFM55 were measured, and its total folate production was 299.72 ± 28.81 ng mL−1. Subsequently, its probiotic properties were explored. The antibacterial test showed that its inhibition zone diameter against Staphylococcus aureus and Salmonella typhimurium was 15.5 ± 0.82 mm and 13.88 ± 0.98 mm, respectively. The tolerance test results indicated that it maintained good activity in simulated gastrointestinal tract and bile salt environments. In vitro intestinal simulation experiments had confirmed that Lactiplantibacillus plantarum ZFM55 can increase the abundance of beneficial bacteria such as Bifidobacteria in the intestine and inhibit the growth of harmful bacteria such as Escherichia_Shigella. Genomic sequencing indicated that the genetic material of Lactiplantibacillus plantarum ZFM55 contains one chromosome and three plasmids, and it has 20 genes related to folate synthesis, which explains its ability to produce folate. CONCLUSION: This study reports a new potential probiotic that produces folate, and provides ideas for exploring probiotics with specific probiotic characteristics. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Salmonella infections are a serious global health concern, particularly in developing countries, and are further exacerbated by the emergence of antibiotic resistance. San‐Huang‐Xie‐Xin‐Tang (SHXXT), a traditional herbal medicine with potent anti‐inflammatory properties, has recently gained attention as an alternative treatment. Our study emphasizes on the importance of precise timing in accordance with traditional Chinese medicine principles. A mouse infection model was established while different administration times of SHXXT were recorded for the body weight, clinical scores, bacterial counts in blood, and organs. Additionally, cytokine levels, fatty acids, and amino acids in the serum were also monitored. We found that administering SHXXT 1 day after Salmonella enterica subsp. enterica serovar Typhimurium (S. Typhimurium) infection (T1 group) leads to positive outcomes. This includes restoration of body weight, improved clinical scores, and reduced bacterial counts in blood and vital organs. Interferon‐gamma levels remained consistently high across all treatment groups 6 days post‐infection. However, the T1 group showed exclusive suppression of serum levels of tumor necrosis factor‐alpha (TNF‐α) and interleukin‐1 beta (IL‐1β). The timing of administration significantly influenced serum fatty acid concentrations, countering Salmonella‐induced disruptions, aligning with TNF‐α and IL‐1β levels. SHXXT had also restored amino acid profiles disrupted by the infection, with notable effects when administered at the correct timing. Our research highlights SHXXT's potential in treating S. Typhimurium infection, emphasizing the importance of precise timing in line with traditional Chinese medicine principles for effective treatment at different disease stages. [ABSTRACT FROM AUTHOR]

The effects of both live and heat‐killed states of Lactiplantibacillus plantarum MWFLp‐182 (L. plantarum MWFLp‐182) isolated from the faeces of long‐lived humans on preventing and relieving Salmonella infection were studied. Evaluation methods included RT‐qPCR measurement of inflammatory factors, histopathological analysis and non‐targeted metabolomics. The results showed that L. plantarum MWFLp‐182 in both states improved body weight loss, organ swelling and ileocolon pathological damage. They also protected against Salmonella infection by regulating key KEGG enrichment pathways and the expression levels of TNF‐a and IL‐6. It is worth noting that the function of live bacteria was better than that of heat‐killed bacteria. [ABSTRACT FROM AUTHOR]

The speciation of Salmonella occurred by acquisition of genomic islands from other bacterial species and continued to diverge into subspecies and serovars with diferent range of host. S. enterica serovar Typhimurium (STM) is a generalist pathogen infecting hosts that include birds, mice, and humans, whilst S. enterica serovar Typhi (STY) is a restricted-host pathogen, infecting only humans. Despite their ranges of hosts, STM and STY possess 97-98% identity. Gain of genes by horizontal transference and loss of genes by mutations, are believed essential for differentiation of Salmonella. Salmonella pathogenicity island 3 (SPI-3) is an example combining these two processes. SPI-3 encodes misL and marT, among other genes. In STM, misL is required for gut colonization. Furthermore, protein MarT, positively regulates expression of misL by binding to misL-promoter. On the other hand, in SPI-3 of STY, marT and misL are pseudogenes. Interestingly, the gene t3766 (gene involved in resistance to H2O2) is present only in STY and is negatively regulated when marTSTM is heterologously expressed in STY. Based on the view that MarT might regulate genes implicated in virulence, this work searched for new genes regulated by MarT. In silico searches for possible MarT target genes were performed, and 4 genes were selected for further analysis as they contained at least 2 copies of the consensus MarT-binding sequence in their promoters. Mutating marT in STM or heterologously expressing marTSTM in STY confirmed that MarT negatively regulates ORF STY1408 or STM14_2003, its homologue in STM. STY1408 encodes for a putative protein with homology to methyl accepting chemotaxis proteins, which participate in chemotaxis and motility. Therefore, STY1408 was named mrmI (MarT-regulated motility gene I). Motility assays confirmed that the product of mrmI modulates motility. In addition, in vitro infection of cells with STM and STY mutants in mrmI reduces association with cells at 1, 3 and 24 h post-infection. Oral infection of mice showed that a mrmI null mutant was defective in producing systemic disease. Therefore, we conclude that MarT regulated mrmI, is involved in virulence of Salmonella. While pseudogenization of marT might modulate the fitness of narrow host range STY. [ABSTRACT FROM AUTHOR]

Contamination of poultry products by Salmonella enterica serovar Typhimurium (STm) is a major cause of foodborne infections and outbreaks. This study aimed to assess the diversity and antimicrobial resistance (AMR) carriage of STm in three chicken processing plants using genomic sequencing. It also aimed to investigate whether any particular strain types were associated with cases of human illness. Multilevel genome typing (MGT) was used to analyze 379 STm isolates from processed chicken carcasses. The diversity of chicken STm sequence types (STs) increased from MGT1 (2 STs) to MGT9 (257 STs). STs at MGT5 to MGT9 levels that were unique to one processing plant and shared among the processing plants were identified, likely reflecting the diversity of STm at their farm source. Fifteen medium resolution MGT5 STs matched those from human infections in Australia and globally. However, no STs matched between the chicken and human isolates at high resolution levels (MGT8 or MGT9), indicating the two STm populations were phylogenetically related but were unlikely to be directly epidemiologically linked. AMR genes were rare, with only a blaTEM-1 gene carried by a 95 kb IncI1 Alpha plasmid being identified in 20 isolates. In conclusion, subpopulations that were widespread in processing plants and had caused human infections were described using MGT5 STs. In this STM population, AMR was rare with only sporadic resistance to a single drug class observed. The genomic analysis of STm from chicken processing plants in this study provided insights into STm that contaminate meat chickens early in the food production chain. [ABSTRACT FROM AUTHOR]

Salmonella Typhimurium (ST) infection in pigs poses a significant threat to animal health and food safety; the intricate mechanisms underlying host–immune responses and pathogen persistence remain poorly understood. To address this knowledge gap, we comprehensively analyzed the peripheral blood transcriptome in piglets infected with ST. We performed histopathological evaluation, blood parameter analysis, advanced RNA-sequencing techniques, and quantitative reverse transcription PCR (RT-qPCR)-based validation. The increasement in the monocyte counts at 2 days post-infection suggested its potential to serve as a hematological marker for ST infection in piglets. Functional and pathway enrichment analyses of the differentially expressed genes highlighted the pivotal roles of innate and adaptive immune responses, notably in pathways associated with Toll-like receptors, NIK/NF-κB signaling, cytokine signaling, and T cell proliferation. RT-qPCR-based validation using peripheral blood mononuclear cells provided additional insights into the immune system dynamics in response to ST infection, revealing the marked elevation of the interleukin (IL)-15, IL-27, and CXCL10 levels being significantly elevated in ST-infected piglets. Our comprehensive analysis underscores the multifaceted impact of ST infection on piglets and offers valuable insights into the host–pathogen interactions and the role of host immune system during ST infection. [ABSTRACT FROM AUTHOR]

In mammals, enteric salmonellas can use tetrathionate (ttr), formed as a by-product from the inflammatory process in the intestine, as electron acceptor in anaerobic respiration, and it can fuel its energy metabolism by degrading the microbial fermentation product 1,2-propanediol. However, recent studies have shown that this mechanism is not important for Salmonella infection in the intestine of poultry, while it prolongs the persistence of Salmonella at systemic sites in this species. In the current study, we show that ΔttrApduA strains of Salmonella enterica have lower net survival within chicken-derived HD-11 macrophages, as CFU was only 2.3% (S. Enteritidis ΔttrApduA), 2.3% (S. Heidelberg ΔttrApduA), and 3.0% (S. Typhimurium ΔttrApduA) compared to wild-type strains after 24 h inside HD-11 macrophage cells. The difference was not related to increased lysis of macrophages, and deletion of ttrA and pduA did not impair the ability of the strains to grow anaerobically. Further studies are indicated to determine the reason why Salmonella ΔttrApduA strains survive less well inside macrophage cell lines. [ABSTRACT FROM AUTHOR]

Bacteria‐initiated cancer therapy has been demonstrated high therapeutic efficacy against cancer. However, the undesired therapeutic efficacy and induced systematic inflammation storm compromise the therapeutic effect and outcome. Herein, a thermally‐activated living nanomedicine composed of reactive biohybrid (designated as Sa@FeS) is rationally designed and engineered for enhancing hydrogen sulfide (H2S)‐combined chemodynamic oncotherapy by biomineralizing ferrous sulfide nanoparticles (FeS NPs) onto the surface of a Salmonella typhimurium strain (Sa) without reducing bacterial activity. Ascribed to the deep penetration capability of Sa, FeS NPs facilitate photothermally‐enhanced catalytic Fenton reaction of decomposing endogenous H2O2 into cytotoxic hydroxyl radicals deep in tumor tissues upon near infrared irradiation. Meanwhile, Sa bacteria maintain sustained H2S release within tumor for achieving H2S‐induced intracellular acidosis that favors the generation of reactive oxygen species synergistically. Of note, the thermally‐triggered all‐in‐one strategy effectively inhibits bacterial viability, thus reducing the risk of systematic inflammation storm and ensuring biosafety. Therefore, the engineered nano‐bacteria living system exerts the thermally‐enhanced nanocatalytic and gas therapies to effectively eradicate tumors, providing a distinct paradigm for the combination of synthetic biology and nanomedicine in tumor therapy. [ABSTRACT FROM AUTHOR]

In the current study, two Salmonella Typhimurium strains, JOL 912 and JOL 1800, were engineered from the wild-type JOL 401 strain through in-frame deletions of the lon and cpxR genes, with JOL 1800 also lacking rfaL. These deletions significantly attenuated the strains, impairing their intracellular survival and creating unique immunological profiles. This study investigates the response of these strains to various abiotic stress conditions commonly experienced in vivo, including temperature, acidity, osmotic, and oxidative stress. Notably, cold stress induced a non-significant trend towards increased invasion by Salmonella compared to other stressors. Despite the observed attenuation, no significant alterations in entry mechanisms (trigger vs. zipper) were noted between these strains, although variations were evident depending on the host cell type. Both strains effectively localized within the cytoplasm, demonstrating their ability to invade and interact with the intracellular environment. Immunologically, JOL 912 elicited a robust response, marked by substantial activation of nuclear factor kappa B (NF-kB), and chemokines, interleukin 8 (CXCL 8) and interleukin 10 (CXCL 10), comparable to the wild-type JOL 401 (over a fourfold increase compared to JOL 1800). In contrast, JOL 1800 exhibited a minimal immune response. Additionally, these attenuations influenced the expression of cyclins D1 and B1 and caspases 3 and 7, indicating cell cycle arrest at the G2/M phase and promotion of the G0/G1 to S phase transition, alongside apoptosis in infected cells. These findings provide valuable insights into the mechanisms governing the association, internalization, and survival of Salmonella mutants, enhancing our understanding of their regulatory effects on host cell physiology. [ABSTRACT FROM AUTHOR]

Outer membrane vesicles (OMVs) produced by Gram-negative bacteria have key roles in cell envelope homeostasis, secretion, interbacterial communication, and pathogenesis. The facultative intracellular pathogen Salmonella Typhimurium increases OMV production inside the acidic vacuoles of host cells by changing expression of its outer membrane proteins and modifying the composition of lipid A. However, the molecular mechanisms that translate pH changes into OMV production are not completely understood. Here, we show that the outer membrane protein PagC promotes OMV production through pH-dependent interactions between its extracellular loops and surrounding lipopolysaccharide (LPS). Structural comparisons and mutational studies indicate that a pH-responsive amino acid motif in PagC extracellular loops, containing PagC-specific histidine residues, is crucial for OMV formation. Molecular dynamics simulations suggest that protonation of histidine residues leads to changes in the structure and flexibility of PagC extracellular loops and their interactions with the surrounding LPS, altering membrane curvature. Consistent with that hypothesis, mimicking acidic pH by mutating those histidine residues to lysine increases OMV production. Thus, our findings reveal a mechanism for sensing and responding to environmental pH and for control of membrane dynamics by outer membrane proteins. The pathogen Salmonella Typhimurium increases production of outer membrane vesicles (OMVs) inside acidic vacuoles of host cells, but the mechanisms are unclear. Here, Dehinwal et al. show that acidic pH induces conformational changes in an outer membrane protein that affect its interaction with membrane lipids, thus modulating OMV formation. [ABSTRACT FROM AUTHOR]

Bacterial pathogens utilize the factors of their hosts to infect them, but which factors they exploit remain poorly defined. Here, we show that a pathogenic Salmonella enterica serovar Typhimurium (STm) exploits host polyamines for the functional expression of virulence factors. An STm mutant strain lacking principal genes required for polyamine synthesis and transport exhibited impaired infectivity in mice. A polyamine uptake-impaired strain of STm was unable to inject effectors of the type 3 secretion system into host cells due to a failure of needle assembly. STm infection stimulated host polyamine production by increasing arginase expression. The decline in polyamine levels caused by difluoromethylornithine, which inhibits host polyamine production, attenuated STm colonization, whereas polyamine supplementation augmented STm pathogenesis. Our work reveals that host polyamines are a key factor promoting STm infection, and therefore a promising therapeutic target for bacterial infection. Bacterial pathogens often exploit host factors to enhance their infectivity. This study shows that Salmonella Typhimurium boosts host polyamine production, which is crucial for the expression and needle assembly of its type 3 secretion system. [ABSTRACT FROM AUTHOR]

In Escherichia coli and Salmonella typhimurium, cysteine biosynthesis requires the products of 20 or more cys genes co-ordinately regulated by CysB. Under conditions of sulphur limitation and in the presence of the inducer, N-acetylserine, CysB binds to cys promoters and activates the transcription of the downstream coding sequences. CysB is a homotetramer, comprising an N-terminal DNA binding domain (DBD) and a C-terminal effector binding domain (EBD). The crystal structure of a dimeric EBD fragment of CysB from Klebsiella aerogenes revealed a protein fold similar to that seen in Lac repressor but with a different symmetry in the dimer so that the mode of DNA binding was not apparent. To elucidate the subunit arrangement in the tetramer, we determined the crystal structure of intact CysB in complex with N-acetylserine. The tetramer has two subunit types that differ in the juxtaposition of their winged helix-turn-helix DNA binding domains with respect to the effector binding domain. In the assembly, the four EBDs form a core with the DNA binding domains arranged in pairs on the surface. N-acetylserine makes extensive polar interactions in an enclosed binding site, and its binding is accompanied by substantial conformational rearrangements of surrounding residues that are propagated to the protein surface where they appear to alter the arrangement of the DNA binding domains. The results are (i) discussed in relation to the extensive mutational data available for CysB and (ii) used to propose a structural mechanism of N-acetylserine induced CysB activation. [ABSTRACT FROM AUTHOR]

Salmonella Typhimurium (S. Typhimurium) contamination poses a significant challenge to breeder egg hatchability and chick health, necessitating the exploration of alternative disinfection methods. This study investigates the potential of phage vB_SPuM_SP02 (SP02) as a novel disinfectant for breeder eggs contaminated with S. Typhimurium SM022. Phage SP02 was isolated from poultry farm effluent and characterized for morphology, biological properties, and genome properties. Experimental groups of specific pathogen-free (SPF) eggs were treated with Salmonella and phage SP02, and efficacy was assessed through hatching rates, chick survival, weight, Salmonella load, immune organ indices, and intestinal flora. Phage treatment effectively eradicated Salmonella contamination on eggshells within 12 h, resulting in increased hatching and survival rates compared to controls. Furthermore, phage treatment mitigated weight loss and tissue Salmonella load in chicks without causing immune organ damage while reducing Salmonella spp. abundance in the intestinal tract. This study demonstrates the potential of phage SP02 as an eco-friendly and efficient disinfectant for S. Typhimurium-contaminated breeder eggs, offering promising prospects for practical application in poultry production. [ABSTRACT FROM AUTHOR]

Fabiana punensis S. C. Arroyo is a subshrub or shrub that is indigenous to the arid and semiarid region of northern Argentina and is known to possess several medicinal properties. The objective of this study was to optimize the extraction conditions so as to maximize the yield of bioactive total phenolic compound (TPC) and flavonoids (F) of F. punensis' aerial parts by using non-conventional extraction methods, namely ultrasound-assisted extraction, UAE, and microwave-assisted extraction, MAE, and to compare the biological activities and toxicity of optimized extracts vs. conventional extracts, i.e., those gained by maceration. Response Surface Methodology (RSM) was used to apply factorial designs to optimize the parameters of extraction: solid-to-liquid ratio, extraction time, ultrasound amplitude, and microwave power. The experimental values for TPC and F and antioxidant activity under the optimal extraction conditions were not significantly different from the predicted values, demonstrating the accuracy of the mathematical models. Similar HPLC-DAD patterns were found between conventional and UAE- and MAE-optimized extracts. The main constituents of the extracts correspond to phenolic compounds (flavonoids and phenolic acids) and apigenin was identified. All extracts showed high scavenger capacity on ABTS•+, O2•− and H2O2, enabling the inhibition of the pro-inflammatory enzymes xanthine oxidase (XO) and lipoxygenase (LOX). They also showed an antimutagenic effect in Salmonella Typhimurium assay and cytotoxic/anti-proliferative activity on human melanoma cells (SKMEL-28). Toxicological evaluation indicates its safety. The results of this work are important in the development of efficient and sustainable methods for obtaining bioactive compounds from F. punensis for the prevention of chronic degenerative diseases associated with oxidative stress, inflammation, and DNA damage. [ABSTRACT FROM AUTHOR]

Food‐related stresses such as heating and freezing may influence the biofilm formation ability of bacteria. This study aimed to investigate the main and interactive effects of food‐related stresses on the biofilm formation potential of Salmonella strains isolated from meat. Salmonella enteritidis, Salmonella typhi, and Salmonella typhimurium were subjected to osmotic, acid, heat, cold, and freezing stresses. The colorimetric microtiter plate method was used to measure the biofilm formation ability as a response to the stresses. Among the main effects, freezing time had the most significant effect on the biofilm formation responses of three Salmonella serovars. Freezing reduced the biofilm formation ability of Salmonella typhimurium and Salmonella enteritidis but increased that of Salmonella typhi (p < 0.05). Among the interaction effects, the most significant effect on the biofilm formation response of Salmonella typhi was the interaction between pH and heat, which had a negative effect on the biofilm formation response. In contrast, the interaction between osmotic pressure and cold stresses was the most significant interactive effect on the biofilm formation responses of Salmonella enteritidis and Salmonella typhimurium, which had an increasing effect. This study concluded that the food‐related stresses could change the biofilm formation capacity of Salmonella serotypes, and each serotype might show different biofilm formation abilities in response to different stresses. [ABSTRACT FROM AUTHOR]

Objectives To characterize bla NDM-carrying Salmonella recovered from a pig slaughterhouse. Methods In this study, 46 environment samples were collected from a slaughterhouse in China, and screened for carbapenem-resistant Enterobacterales. WGS, antimicrobial susceptibility testing and conjugation experiments were carried out to identify the isolates' resistance phenotypes and genetic characteristics. The phylogenetic relatedness of the Salmonella isolates obtained in this study and Salmonella (ST34 and ST29) in GenBank was determined. Results Two ST34 Salmonella Typhimurium and one ST29 Salmonella Stanley, recovered from three environmental samples (6.52%), were positive for bla NDM-1 and bla NDM-5, respectively. The two ST34 S. Typhimurium strains exhibited a close relationship (10–36 SNPs) with two human-derived bla NDM-1-bearing isolates from China (Hong Kong and Guangxi Province) and two bla NDM-negative ST34 Salmonella strains from the UK. The bla NDM-1 genes were located on IncHI2/ST3 plasmids. The capture of bla NDM-1 by the IncHI2/ST3 plasmid seems to be due to homologous recombination mediated by circular structures, as the genetic arrangements of the bla NDM-1 gene contain two IS 26 elements of the same orientation. The bla NDM-5 gene was also carried by the IncHI2/ST3 plasmid, which shares highly similar structures with other bla NDM-5-bearing IncHI2/ST3 plasmids from other sources (fish, chicken, duck, human). Conclusions This is the first report of a bla NDM-5-carrying IncHI2/ST3 plasmid in Salmonella. The clonal spread of NDM-1-producing ST34 S. Typhimurium across human and animal-associated environments, and the widespread dissemination of epidemic bla NDM-5-carrying IncHI2/ST3 plasmids among Enterobacteriaceae in China indicate the potential of further dissemination of bla NDM among Salmonella , which poses a threat to public health. [ABSTRACT FROM AUTHOR]

Aims: Salmonella infections are significant causes of foodborne outbreaks in the European Union. This study investigates a sudden increase in gastroenteritis patients in the hospital district of Central Finland in June 2021. The primary aim was to study the outbreak's magnitude and source of the outbreak. Methods and Results: Epidemiological, microbiological, environmental and traceback investigations were conducted. Over 700 persons fell ill during the outbreak caused by Salmonella Typhimurium associated with a daycare lunch. Similar S. Typhimurium was found in the patients and a vegetable mix containing iceberg lettuce, cucumber and peas served during lunch. The traceback investigation revealed that the batch information of vegetables from the wholesaler was not complete. The wholesaler had received quality complaints about the iceberg lettuce from the central kitchen. The manufacturer did not test the suspected batch for Salmonella since the production plant had given a certificate declaring it Salmonella negative. Conclusions: The most suspect ingredient was one batch of iceberg lettuce due to quality complaints. The lettuce had not been served in two daycare centres without cases. We recommend that in order to enable thorough microbiological investigation, institutional kitchens store the food samples separately as part of the internal quality control and that food items should always be tested when Salmonella contamination in an outbreak is suspected. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the phenotypic and genotypic responses of Salmonella Typhimurium ATCC 19585 (ST) and Staphylococcus aureus KACC 13236 (SA) preadapted to sublethal concentrations of lactic acid (LA) and sodium chloride (NaCl) for 48 hr at 37°C, followed by re-exposure to lethal concentrations of LA and NaCl for 24 hr at 37°C. ST and SA treated in a sequential and ordered manner with LA and NaCl were assigned as LA-LA, LA-NaCl, NaCl-LA, and NaCl-NaCl. The treatments, LA-LA, LA-NaCl, NaCl-LA, and NaCl-NaCl, were evaluated by antimicrobial susceptibility, bacterial fluctuation, relative fitness, zeta potential, and gene expression. The MICt/MICc ratios of LA, NaCl, CIP, GEN, and TET against ST treated with LA-LA were 1.0 to 0.8, 0.8, 0.3, 0.4, and 0.5, respectively. The MICt/MICc ratios of NaCl, CIP, GEN, and TET were between 0.5–0.8 for SA treated with LA-LA. ST treated with LA-LA and SA treated with LA-NaCl exhibited the highest coefficient of variance. The lowest relative fitness was observed at ST treated with LA-LA (0.5). ST and SA treated with LA-LA showed the lowest zeta potential. The transporter-, toxin–antitoxin system-, chaperone protein-, and SOS response-related genes were suppressed at ST and SA treated with LA-LA. The transporter-, toxin–antitoxin system-, and chaperone protein-related genes were overexpressed in SA treated with LA-NaCl, NaCl-LA, and NaCl-NaCl. The results suggest that ST and SA treated with LA-LA, LA-NaCl, NaCl-LA, and NaCl-NaCl could induce collateral sensitivity and cross-resistance. [ABSTRACT FROM AUTHOR]

The wide biological activity of the Moringa oleifera represents a potential opportunity for developing selective cancer treatment drugs. The bioactive phytochemicals in Moringa seed extract (MSE) indicated large numbers of phytochemicals (21 compounds) with dominant abundance for cycloisolongifolene, 8,9‐dehydro‐9‐vinyl, and chamazulene accounting for 12.7% and 12.19% of the total detected compounds. The MSE showed a potent anticancer effect toward Caco‐2, MDA, and HepG‐2 cells with half‐maximal inhibitory concentration (IC50) values of 9.15 ± 1.18, 4.85 ± 0.11, and 7.36 ± 0.22 µg/mL, respectively, with higher safety (≥31‐folds) toward normal human cells (IC50 of 150.7 ± 11.11 µg/mL). It appears that MSE stimulates selective‐dose‐dependent cell shrinkage, and nuclear condensation in the tumor cells, which finally induces the apoptosis pathway to increase its anticancer action. Additionally, MSE showed a potent capability to stimulate cell cycle arrest in both main checkpoint phases (G0/G1 and G2/M) of cell population growth. The apoptotic death stimulation was confirmed through upregulation of tumor protein p53 (p53) and cyclin‐dependent kinase inhibitor p21 (p21) expression by more than three‐ to sixfold and downregulation of B‐cell lymphoma 2 expression (threefold) in MSE‐treated cells compared to 5‐fluorouracil (5‐FU)‐treated tumor cells. Furthermore, the MSE revealed strong anti‐inflammatory activity with significant antioxidant activity by lowering nitric oxide levels and enhancing the superoxide dismutase activity. On the other hand, the MSE revealed broad‐spectrum antibacterial activity in a dose‐dependent manner against Staphylococcus aureus minimum inhibitory concentration (MIC of 1.25 mg/mL), followed by Salmonella typhimurium (MIC of 1.23 mg/mL), whereas Escherichia coli was the least sensitive to MSE activity (MIC of 22.5 mg/mL) with significant antibiofilm activity against sensitive pathogens. [ABSTRACT FROM AUTHOR]

Rapid and high-sensitive Salmonella detection in milk is important for preventing foodborne disease eruption. To overcome the influence of the complex ingredients in milk on the sensitive detection of Salmonella, a dual-signal reporter red fluorescence nanosphere (RNs)-Pt was designed by combining RNs and Pt nanoparticles. After being equipped with antibodies, the immune RNs-Pt (IRNs-Pt) provide an ultra-strong fluorescence signal when excited by UV light. With the assistance of the H2O2/TMB system, a visible color change appeared that was attributed to the strong peroxidase-like catalytic activity derived from Pt nanoparticles. The IRNs-Pt in conjunction with immune magnetic beads can realize that Salmonella typhimurium (S. typhi) was captured, labeled, and separated effectively from untreated reduced-fat pure milk samples. Under the optimal experimental conditions, with the assay, as low as 50 CFU S. typhi can be converted to detectable fluorescence and absorbance signals within 2 h, suggesting the feasibility of practical application of the assay. Meanwhile, dual-signal modes of quantitative detection were realized. For fluorescence signal detection (emission at 615 nm), the linear correlation between signal intensity and the concentration of S. typhi was Y = 83C-3321 (R2 = 0.9941), ranging from 103 to 105 CFU/mL, while for colorimetric detection (absorbamce at 450 nm), the relationship between signal intensity and the concentration of S. typhi was Y = 2.9logC-10.2 (R2 = 0.9875), ranging from 5 × 103 to 105 CFU/mL. For suspect food contamination by foodborne pathogens, this dual-mode signal readout assay is promising for achieving the aim of convenient preliminary screening and accurate quantification simultaneously. [ABSTRACT FROM AUTHOR]

In recent years, development of biopolymeric nanofibers as an active biodegradable packaging system has attracted specific attention. The objective of this research was to develop zein‐based electrospun nanofibers (NFs) incorporated with geraniol‐loaded nanoliposomes (G‐loaded NLPs). Geraniol was encapsulated into NLPs with an efficiency of 79.23%. The particle size and zeta potential of G‐loaded NLPs were 121.50 nm and −38.30 mV, respectively. The successful loading of geraniol in the NLPs was approved by Fourier transform infrared (FT‐IR) spectroscopy. The liposomal vesicles showed spherical shapes. G‐loaded NLPs were added in the zein‐based electrospun NFs at three different concentrations (0.25, 0.5, and 1%w/v). All NFs samples exhibited fibrillar structure. The increase of NLPs concentration enhanced the thermal stability of the NFs. However, the crystalline structure of zein NFs did not change by the addition of G‐loaded NLPs. The highest surface hydrophobicity was related to the NFs containing 1% G‐loaded NLPs. The mechanical parameters of NFs depend on the concentration of NLPs. The NFs incorporated with G‐loaded NLPs showed inhibition activity against four foodborne pathogenic bacteria (Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, and Salmonella typhimurium) with an inhibition zone of 4.5–22 mm. Moreover, the α‐diphenyl‐β‐picrylhydrazyl (DPPH) scavenging activity of NFs samples was located at the range of 20%–48%. These findings represent the Efficiency of the G‐loaded NLPs for use as bioactive compound in the zein‐based NFs as an active packaging material. [ABSTRACT FROM AUTHOR]

Background: The use of plants in the treatment of microbial diseases is increasing worldwide; especially with the increase of bacterial resistance to antibiotics and the development of new diseases that have no cure in modern medicines. Aim: This research was designed to determine the antimicrobial activities of bioactive compounds isolated from Acacia nilotica (A. nilotica) against multi-drug resistant bacteria. Methods: Acacia nilotica samples (i.e., leaves, pods, and back) were collected within Aliero local government area, in Nigeria. Metabolite extraction was performed through maceration. The obtained extract was tested in vitro against multi-drug resistant bacteria that cause diarrhea: Salmonella typhimurium, S. paratyphi, Salmonella sp, Shigella dysenteriae, Shigella sp, and Shigella flexneri, using the agar well diffusion assay. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined using the micro-plate serial dilution method. The synergistic (Pod + Leave Steam back) ethanolic crude extract was subjected to column and thin-layer chromatography (TLC) analyses. The obtained fractions were tested against multi-drugs resistance bacteria, and MIC and MBC of the fractions were also determined. Results: The results showed that the synergistic A. nilotica crude extract had the highest mean antibacterial activity recording inhibition zones that ranged from 15.0± 0.58 to 22.7± 0.33 mm. The MIC of ethanolic crude extracts ranged from 100 to 200 mg/ml, while the MBC ranged from 100 to > 400 mg/ ml. Conclusion: The antibacterial potential of the synergistic ethanolic fractions recorded higher activity that ranged from 16.7± 1.20 to 31.0±1.00 mm against all the tested bacteria, compared to the crude extracts. [ABSTRACT FROM AUTHOR]

Soy culture fermented with a koji fungus and lactic acid bacteria (SKL) is a functional food commercially available in Japan, which is produced by cultivating a mixture of soy solution and black sugar with a fungus, six strains of lactic acid bacteria (LAB), and a yeast. We have investigated functionalities of SKL on human health and reported its strong antioxidative and antimutagenic abilities. We then conducted a survival test in which mice were intraperitoneally inoculated with Salmonella Typhimurium JCM1652 following SKL feeding for 4 weeks. Because the mice were protected against the bacterial inoculation in a manner dependent on the SKL dose, we inferred that SKL has the ability to stimulate the innate immune system against bacterial infection, leading us to investigate the immunological potential of SKL. We fractionated SKL into supernatants, fibers, and cells of LAB and conducted several ex vivo and hematological tests, using BALB/c mice and S. Typhimurium JCM1652. Each fraction was mixed with feed of mice and the mice were fed for 2 weeks. After the feeding period, they were killed and peritoneal macrophages, spleen cells, and blood were collected. Phagocytosis and bactericidal activities of macrophages against JCM1652, production of TNF-α by spleen cells stimulated with JCM1652, and levels of TNF-α and other hematological factors in blood were investigated. The phagocytic activity of macrophages was higher in both SKL and fiber fractions than in others, whereas their bactericidal activity was higher in both SKL and cell fractions. The level of TNF-α in the spleen cell culture was the highest in the control, whereas this cytokine was not detected at all in the blood samples from all fractions including the control. The protective effect per mouse, which was defined as the product of three factors (the number of peritoneal macrophages, their phagocytic rate, and their bactericidal rate), was the strongest in SKL. On the basis of these results, we concluded that the protective effect of SKL against the inoculation of JCM1652 is due to activation of the innate immune system of the mice by SKL. We also concluded that oral administration of SKL could exert this effect without inducing inflammation, considering the level of TNF-α in blood. The substances responsible for this immunological potential in SKL may include peptidoglycan of LAB cells and mycelial β-1,3-glucan of the koji fungus, which is one of the major components of the fiber fraction. [ABSTRACT FROM AUTHOR]

Salmonella typhimurium, a pathogenic bacterium with significant implications in medicine and the food industry, poses a substantial threat by causing foodborne illnesses such as typhoid fever. Accurate diagnosis of S. typhimurium is challenging due to its overlap symptoms with various diseases. This underscores the need for a precise and efficient diagnostic approach. In this study, we developed a biosensor using the Taguchi optimization method based on aptamer lateral flow assay (LFA) for the detection of S. typhimurium. Therefore, signal probe and nanobioprobe were designed using anti-Salmonella aptamer, conjugated with gold nanoparticles (GNPs), and used in LFA. The strategy of this test is based on a competitive format between the bacteria immobilized on the membrane and the bacteria present in the tested sample. Moreovere, the optimization of various factors affecting the aptamer LFA, including the concentration of bacteria (immobilized and into the sample) and the concentration of nanobioprop, were performed using the Taguchi test designing method. The data showed that the optimal conditions for the LFA reaction was 108 CFU/mL of immobilized bacteria and 1.5 μg/μL of nanobioprop concentration. Then, the visual detection limit of S. typhimurium was estimated as 105 CFU/mL. The reaction results were obtained within 20 min, and there were no significant cross-reactions with other food pathogens. In conclusion, the aptamer-LFA diagnostic method, optimized using the Taguchi approach, emerges as a reliable, straightforward, and accurate tool for the detection of S. typhimurium. Overall, this method can be a portable diagnostic kit for the detection and identification of bacteria. [ABSTRACT FROM AUTHOR]

The emergence of antimicrobial resistance has created an urgent need for alternative treatments against bacterial pathogens. Here, we investigated kinase inhibitors as potential host-directed therapies (HDTs) against intracellular bacteria, specifically Salmonella Typhimurium (Stm) and Mycobacterium tuberculosis (Mtb). We screened 827 ATP-competitive kinase inhibitors with known target profiles from two Published Kinase Inhibitor Sets (PKIS1 and PKIS2) using intracellular infection models for Stm and Mtb, based on human cell lines and primary macrophages. Additionally, the in vivo safety and efficacy of the compounds were assessed using zebrafish embryo infection models. Our screen identified 11 hit compounds for Stm and 17 hit compounds for Mtb that were effective against intracellular bacteria and non-toxic for host cells. Further experiments were conducted to prioritize Stm hit compounds that were able to clear the intracellular infection in primary human macrophages. From these, two structurally related Stm hit compounds, GSK1379738A and GSK1379760A, exhibited significant activity against Stm in infected zebrafish embryos. In addition, we identified compounds that were active against intracellular Mtb, including morpholino-imidazo/triazolo-pyrimidinones that target PIK3CB, as well as 2-aminobenzimidazoles targeting ABL1. Overall, this study provided insights into kinase targets acting at the host–pathogen interface and identified several kinase inhibitors as potential HDTs. [ABSTRACT FROM AUTHOR]

Invasive non-typhoidal Salmonella (iNTS) disease is an under-recognized high-burden disease causing major health and socioeconomic issues in sub-Saharan Africa (sSA), predominantly among immune-naïve infants and young children, including those with recognized comorbidities such as HIV infection. iNTS disease is primarily caused by Salmonella enterica serovar Typhimurium sequence type (ST) 313 and 'African-restricted clades' of Salmonella Enteritidis ST11 that have emerged across the African continent as a series of epidemics associated with acquisition of new antimicrobial resistance. Due to genotypes with a high prevalence of antimicrobial resistance and scarcity of therapeutic options, these NTS serovars are designated by the World Health Organization as a priority pathogen for research and development of interventions, including vaccines, to address and reduce NTS associated bacteremia and meningitis in sSA. Novel and traditional vaccine technologies are being applied to develop vaccines against iNTS disease, and the results of the first clinical trials in the infant target population should become available in the near future. The "Vaccine Value Profile" (VVP) addresses information related predominantly to invasive disease caused by Salmonella Enteritidis and Salmonella Typhimurium prevalent in sSA. Information is included on stand-alone iNTS disease candidate vaccines and candidate vaccines targeting iNTS disease combined with another invasive serotype, Salmonella Typhi, that is also common across sSA. Out of scope for the first version of this VVP is a wider discussion on either diarrheagenic NTS disease (dNTS) also associated with Salmonella Enteritidis and Salmonella Typhimurium or the development of a multivalent Salmonella vaccines targeting key serovars for use globally. This VVP for vaccines to prevent iNTS disease is intended to provide a high-level, holistic assessment of the information and data that are currently available to inform the potential public health, economic, and societal value of pipeline vaccines and vaccine-like products. Future versions of this VVP will be updated to reflect ongoing activities such as vaccine development strategies and a "Full Vaccine Value Assessment" that will inform the value proposition of an iNTS disease vaccine. This VVP was developed by a working group of subject matter experts from academia, non-profit organizations, public private partnerships, and multi-lateral organizations, and in collaboration with stakeholders from the World Health Organization African Region. All contributors have extensive expertise on various elements of the iNTS disease VVP and collectively aimed to identify current research and knowledge gaps. The VVP was developed using only existing and publicly available information. [ABSTRACT FROM AUTHOR]

Sensitive detection and efficient inactivation of pathogenic bacteria are crucial for halting the spread and reproduction of foodborne pathogenic bacteria. Herein, a novel Apt-modified PDMS-ZnO/Ag multifunctional biosensor has been developed for high-sensitivity surface-enhanced Raman scattering (SERS) detection along with photocatalytic sterilization towards Salmonella typhimurium (S. typhimurium). The distribution of the electric field in PDMS-ZnO/Ag with different Ag sputtering times was analyzed using a finite-difference time-domain (FDTD) algorithm. Due to the combined effect of electromagnetic enhancement and chemical enhancement, PDMS-ZnO/Ag exhibited outstanding SERS sensitivity. The limit of detection (LOD) for 4-MBA on the optimal SERS substrate (PZA-40) could be as little as 10−9 M. After PZA-40 was modified with the aptamer, the LOD of the PZA-40-Apt biosensor for detecting S. typhimurium was only 10 cfu/mL. Additionally, the PZA-40-Apt biosensor could effectively inactivate S. typhimurium under visible light irradiation within 10 min, with a bacterial lethality rate (Lb) of up to 97%. In particular, the PZA-40-Apt biosensor could identify S. typhimurium in food samples in addition to having minimal cytotoxicity and powerful biocompatibility. This work provides a multifunctional nanoplatform with broad prospects for selective SERS detection and photocatalytic sterilization of pathogenic bacteria. [ABSTRACT FROM AUTHOR]

To study the effects of attenuated Salmonella typhimurium L forms on the in vivo tumorigenicity and apoptosis of murine epithelial ovarian cancer cells, as well as the related mechanisms. Attenuated Salmonella typhimurium VNP20009 was induced into bacterial L forms by using antibiotic ceftriaxone. CCK-8 cell proliferation assay showed that attenuated S. typhimurium L forms can inhibit the proliferation of murine ovarian epithelial cancer ID8 cells. Attenuated ST L forms can induce apoptosis and inhibit invasion ability of epithelial ovarian cancer cells in vitro. TUNEL assay showed that attenuated ST L forms can induce apoptosis of ID8 cells in murine ovarian tumors. Meanwhile, attenuated ST L forms inhibit tumor growth in murine ovarian tumors. The tumorigenicity-related proteins of xenograft tumors detected by immunohistochemistry and fluorescence quantitative RT-PCR assays showed that attenuated ST L forms can reduce the expression of proteins that promote tumor growth and metastasis, such as Lgals9 and MMP9. This study confirmed that attenuated ST L forms can suppress tumor growth and promote apoptosis in murine ovarian tumors. Attenuated ST L forms may serve as a novel biological agent for bacterial-mediated tumor therapy in epithelial ovarian cancer. [ABSTRACT FROM AUTHOR]

The escalating incidence of foodborne salmonellosis poses a significant global threat to food safety and public health. As antibiotic resistance in Salmonella continues to rise, there is growing interest in bacteriophages as potential alternatives. In this study, we isolated, characterized, and evaluated the biocontrol efficacy of lytic phage L223 in chicken meat. Phage L223 demonstrated robust stability across a broad range of temperatures (20–70 °C) and pH levels (2–11) and exhibited a restricted host range targeting Salmonella spp., notably Salmonella Typhimurium and Salmonella Enteritidis. Characterization of L223 revealed a short latent period of 30 min and a substantial burst size of 515 PFU/cell. Genomic analysis classified L223 within the Caudoviricetes class, Guernseyvirinae subfamily and Jerseyvirus genus, with a dsDNA genome size of 44,321 bp and 47.9% GC content, featuring 72 coding sequences devoid of antimicrobial resistance, virulence factors, toxins, and tRNA genes. Application of L223 significantly (p < 0.005) reduced Salmonella Typhimurium ATCC 14,028 counts by 1.24, 2.17, and 1.55 log CFU/piece after 2, 4, and 6 h of incubation, respectively, in experimentally contaminated chicken breast samples. These findings highlight the potential of Salmonella phage L223 as a promising biocontrol agent for mitigating Salmonella contamination in food products, emphasizing its relevance for enhancing food safety protocols. [ABSTRACT FROM AUTHOR]

In order to survive and replicate, Salmonella has evolved mechanisms to gain access to intestinal epithelial cells of the crypt. However, the impact of Salmonella Typhimurium on stem cells and progenitors, which are responsible for the ability of the intestinal epithelium to renew and protect itself, remains unclear. Given that intestinal organoids growth is sustained by stem cells and progenitors activity, we have used this model to document the effects of Salmonella Typhimurium infection on epithelial proliferation and differentiation, and compared it to an in vivo model of Salmonella infection in mice. Among gut segments, the caecum was preferentially targeted by Salmonella. Analysis of infected crypts and organoids demonstrated increased length and size, respectively. mRNA transcription profiles of infected crypts and organoids pointed to upregulated EGFR-dependent signals, associated with a decrease in secretory cell lineage differentiation. To conclude, we show that organoids are suited to mimic the impact of Salmonella on stem cells and progenitors cells, carrying a great potential to drastically reduce the use of animals for scientific studies on that topic. In both models, the EGFR pathway, crucial to stem cells and progenitors proliferation and differentiation, is dysregulated by Salmonella, suggesting that repeated infections might have consequences on crypt integrity and further oncogenesis. [ABSTRACT FROM AUTHOR]

Summary: This study delved into the antimicrobial potential of hydrolysates from adzuki bean and mung bean protein concentrates, created using Alcalase and Flavourzyme enzymes. Targeting common foodborne pathogens (Salmonella Typhimurium, Salmonella Enteritidis, Vibrio parahaemolyticus, Staphylococcus aureus, and Bacillus subtilis) and Escherichia coli, the research underscored the crucial role of peptidase in generating antibacterial peptides. Fractions F2 of Flavourzyme hydrolysed adzuki bean (ABF) and F4 of Flavourzyme hydrolysed mung bean (MBF) showed the highest antibacterial activity against S. Typhimurium and S. aureus, respectively, whereas F2 of Alcalase hydrolysed mung bean (MBA) exhibited very poor activity against S. aureus. TripleTOF LC–MS/MS analysis revealed small cationic antibacterial peptides, with lysine being prominent against S. aureus and proline–proline against S. Typhimurium. These findings highlighted the significant contribution of protease enzymes in fostering antibacterial peptide production, offering valuable insights for developing effective antimicrobial agents in the context of food safety. [ABSTRACT FROM AUTHOR]

This study utilized Aspergillus flavus to produce selenium nanoparticles (Se-NPs) in an environmentally friendly and ecologically sustainable manner, targeting several medicinal applications. These biosynthesized Se-NPs were meticulously characterized using X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, transmission electron microscope (TEM), and UV–visible spectroscopy (UV), revealing their spherical shape and size ranging between 28 and 78 nm. We conducted further testing of Se-NPs to evaluate their potential for biological applications, including antiviral, anticancer, antibacterial, antioxidant, and antibiofilm activities. The results indicate that biosynthesized Se-NPs could be effective against various pathogens, including Salmonella typhimurium (ATCC 14028), Bacillus pumilus (ATCC 14884), Staphylococcus aureus (ATCC 6538), Clostridium sporogenes (ATCC 19404), Escherichia coli (ATCC 8739), and Bacillus subtilis (ATCC 6633). Additionally, the biosynthesized Se-NPs exhibited anticancer activity against three cell lines: pancreatic carcinoma (PANC1), cervical cancer (Hela), and colorectal adenocarcinoma (Caco-2), with IC50 values of 177, 208, and 216 μg/mL, respectively. The nanoparticles demonstrated antiviral activity against HSV-1 and HAV, achieving inhibition rates of 66.4% and 15.1%, respectively, at the maximum non-toxic concentration, while also displaying antibiofilm and antioxidant properties. In conclusion, the biosynthesized Se-NPs by A. flavus present a promising avenue for various biomedical applications with safe usage. [ABSTRACT FROM AUTHOR]

Humans are frequently exposed to various carcinogens capable of inducing cancer in multiple organs. Phyllanthus emblica (P. emblica) is known for its strong antioxidant properties and potential in cancer prevention. However, its effectiveness against combined carcinogens remains relatively unexplored. This study aimed to assess the chemopreventive potential of the ethanolic extract of P. emblica fruits against preneoplastic lesions in the liver and colon using a rat model. Rats were administered with diethylnitrosamine (DEN) and 1,2-dimethylhydrazine (DMH) to induce hepato- and colon carcinogenesis, respectively. The ethanolic extract of P. emblica fruit at 100 and 500 mg/kg bw significantly reduced the number of preneoplastic lesions in the liver by 74.7% and 55.6%, respectively, and in the colon by 39.2% and 40.8%, respectively. Similarly, the extract decreased the size of preneoplastic lesions in the liver by 75.2% (100 mg/kg bw) and 70.6% (500 mg/kg bw). Furthermore, the extract significantly reduced the cell proliferation marker in the liver by 70.3% (100 mg/kg bw) and 61.54% (500 mg/kg bw), and in the colon by 62.7% (100 mg/kg bw) and 60.5% (500 mg/kg bw). The ethanolic extract also enhanced liver antioxidant enzyme activities and demonstrated free radical scavenging in DPPH, ABTS, and FRAP assays. Additionally, the dichloromethane fraction of P. emblica showed significant cancer prevention potential by reducing intracellular ROS and NO production by 61.7% and 35.4%, respectively, in RAW 264.7 macrophages. It also exhibited antimutagenic effects with a reduction of 54.0% against aflatoxin B1 and 52.3% against 2-amino-3,4-dimethylimidazo[4,5-f]quinoline-induced mutagenesis in Salmonella typhimurium. Finally, this study highlights the chemopreventive activity of P. emblica fruit extract against the initiation of early-stage carcinogenic lesions in the liver and colon in rats treated with dual carcinogens. [ABSTRACT FROM AUTHOR]

Salmonella Typhimurium is an enteric pathogen that is highly tolerant to bile. Next‐generation mRNA sequencing was performed to analyze the adaptive responses to bile in two S. Typhimurium strains: wild type (WT) and a mutant lacking cold shock protein E (ΔcspE). CspE is an RNA chaperone which is crucial for survival of S. Typhimurium during bile stress. This study identifies transcriptional responses in bile‐tolerant WT and bile‐sensitive ΔcspE. Upregulation of several genes involved in nitrate metabolism was observed, including fnr, a global regulator of nitrate metabolism. Notably, Δfnr was susceptible to bile stress. Also, complementation with fnr lowered reactive oxygen species and enhanced the survival of bile‐sensitive ΔcspE. Importantly, intracellular nitrite amounts were highly induced in bile‐treated WT compared to ΔcspE. Also, the WT strain pre‐treated with nitrate displayed better growth with bile. These results demonstrate that nitrate‐dependent metabolism promotes adaptation of S. Typhimurium to bile. [ABSTRACT FROM AUTHOR]

In the current investigation, the antibacterial activity of zinc oxide nanoparticles (ZnO-NPs) formed by an aqueous extract of Psidium guajava leaves against foodborne pathogenic bacterial strains was investigated. To achieve this goal, 33 bacterial isolates were obtained from spoiled fruits. Among these isolates, 79% showed cellulase activity, 82% showed amylase activity, 81% exhibited xylanase potential, and 65% exhibited lipase activity. Moreover, 12 isolates showed complete hemolysis (β-hemolysis). The identification of these isolates was done using sequencing and amplification of 16s rRNA as Staphylococcus aureus (two strains), Pseudomonas syringae (one strain), E. coli (two strains), Salmonella typhimurium (two strains), Listeria monocytogenes (one isolate), Bacillus cereus (two isolates), and Bacillus subtilis (two isolates). The formed ZnO-NPs by aqueous Psidium guajava leaf extract were characterized using UV, FT-IR, TEM, EDX, XRD, DLS, and Zeta potential. The data revealed the successful formation of a spherical shape, crystallographic structure, and well-arranged ZnO-NPs. FT-IR showed the effect of different functional groups in the plant extract in the formation of ZnO-NPs through reducing, capping, and stabilizing of end products. Moreover, EDX analysis showed that the Zn ion occupied the main component of the produced NPs. Interestingly, the obtained bacterial strains showed varied sensitivity toward green-synthesized ZnO-NPs. The growth inhibition of foodborne pathogenic strains by ZnO-NPs was concentration dependent, forming a zone of inhibition in the range of 20–23 mm at a concentration of 200 µg mL−1, which decreased to 15–18 mm at 100 µg mL−1. Moreover, the values of MIC were 25 and 50 µg mL−1 based on the bacterial strain. Overall, the green-synthesized ZnO-NPs can be a useful approach for inhibiting the growth of spoilage bacterial strains that destroy fruits and hence reduce the harmful effects of traditional treatment methods on the environment and human health. [ABSTRACT FROM AUTHOR]

Salmonella is a hazardous bacterium that can lead to dangerous human infections, as well as catastrophic losses in chicken production. Disinfectants are frequently used in chicken houses to prevent the spread of zoonotic infections such as Salmonella strains. The emergence of bacteria strains resistant to various disinfectants is a serious problem when using disinfectants. The resistance of certain Salmonella serotypes to quaternary ammonium compounds is a feature of these phenomena and some Salmonella spp. may carry the qacEDl and qacA/B genes, which are responsible for this resistance. So the purpose of this study was to identify Salmonella serotypes and determine the most important virulence genes of the serotypes obtained from samples taken from dead chicken embryos. Evaluation of the resistance of Salmonella strains against various disinfectants (Quaternary ammonium compounds QACS, iodine, and virkon S) and determined the minimum inhibitory concentration (MIC) to investigate the antibacterial potential of plant essential oil components, such as thymol, cinnamaldehyde, and zingiberene, against Salmonella serotypes. A total of 115 samples were collected from dead chicken embryos, after isolation Salmonella isolates were reported to be 16/115 (13.9%). The most prevalent serotypes were Salmonella typhimurium, Salmonella kentucky, Salmonella anatum and Salmonella poona. Through the treatment of the bacteria at various concentrations, the effectiveness of the disinfectant was determined. Research has shown that the type and concentration of the disinfectant affect its biocidal activity. PCR was also used to detect the presence of qacED1 and qacA/B genes. [ABSTRACT FROM AUTHOR]

Background: Due to their potential for treating a variety of common illnesses, medicinal plants have recently attracted a lot of attention, also other medicinal assertions are now supported by a wealth of scientific evidence, so nowadays natural products such as essential oils (EOs) and crude extracts provide boundless opportunities for novel drugs. Objective: This Study was carried out to investigate the antiviral and antibacterial activity of an essential oils product, Deca-Cel®, against Newcastle disease virus (NDV), Lasota strain, as a viral model and multidrug-resistant Escherichia coli and Salmonella Typhimurium as bacterial models. Methodology: The antiviral activity of these EOs was systematically studied in three experimental protocols viz. virucidal, therapeutic and prophylactic assays employing in ovo model. Firstly, toxicity study was estimated for screening the optimal non- toxic concentration of the EOs in the embryonated chicken eggs and then their antiviral efficacy was determined. Embryo survival was observed by candling daily and the survival rates of embryos were recorded on day 4th post-inoculation (pi). After the end of experiments, survivors were killed by chilling the eggs in a refrigerator for further examination and allantoic fluid from treated eggs was collected for rapid hemagglutination (HA) test to detect NDV. Minimum inhibitory concentration (MIC) values are used to determine the susceptibilities of some bacterial agents to these EOs to evaluate their antibacterial activity. Results: For studying their antiviral activity, it was found that Deca-Cel® oil can completely inhibit NDV growth with a high embryo survival rate reaching 100% with -ve HA activity as a virucidal and prophylactic agent, while 60% embryo survival rate and negative hemagglutination activity had been recorded as a therapeutic agent, comparing to virus control which showed 100% embryo mortality rate within 48:72hrs pi with strong positive HA activity. Regarding the antibacterial activity, it was found that MIC values of these EOs were 0.4 µL/ml and 0.2 µL/ml against Salmonella Typhimurium and E. coli respectively, which means that these EOs can be used as a good alternative to antibiotics that recently showing resistance. Conclusion: The current findings have demonstrated that these EOs have promising antiviral and antibacterial properties against many avian pathogens. [ABSTRACT FROM AUTHOR]

This study performed microbial analysis of nutrient film technique (NFT) hydroponic systems on three indoor farms in Singapore (the "what"). To justify the necessity of sanitizing hydroponic systems, strong biofilm-forming bacteria were isolated from the facility and investigated for their influence on Salmonella colonization on polyvinyl chloride (PVC) coupons in hydroponic nutrient solutions (the "why"). Finally, sanitization solutions were evaluated with both laboratory-scale and field-scale tests (the "how"). As a result, the microbiome composition in NFT systems was found to be highly farm specific. The strong biofilm formers Corynebacterium tuberculostearicum C2 and Pseudoxanthomonas mexicana C3 were found to facilitate the attachment and colonization of Salmonella on PVC coupons. When forming dual-species biofilms, the presence of C2 and C3 also significantly promoted the growth of Salmonella (P < 0.05). Compared with hydrogen peroxide (H2O2) and sodium percarbonate (SPC), sodium hypochlorite (NaOCl) exhibited superior efficacy in biofilm removal. At 50 ppm, NaOCl reduced the Salmonella Typhimurium, C2, and C3 counts to <1 log CFU/cm² within 12 h, whereas neither 3% H2O2 nor 1% SPC achieved this effect. In operational hydroponic systems, the concentration of NaOCl needed to achieve biofilm elimination increased to 500 ppm, likely due to the presence of organic matter accumulated during crop cultivation and the greater persistence of naturally formed multispecies biofilms. Sanitization using 500 ppm NaOCl for 12 h did not impede subsequent plant growth, but chlorination byproduct chlorate was detected at high levels in the hydroponic solution and in plants in the sanitized systems without rinsing. [ABSTRACT FROM AUTHOR]

Beef carcass evaluation is generally the basis for judging the commercial value of the livestock and is consequently one of the most common quality control tests carried out in the meat industry. In the current study, sixty swabs were taken from the outer surface of neck and groin (30 of each) of freshly dressed beef carcasses taken from three local slaughterhouses located in El-Bagour, El-May and El-Shohadaa provinces of Menoufia governorate, Egypt. Swabs were microbiologically examined; the results revealed that groin samples had significantly (P≤0.05) lower contamination levels than that of neck samples. In addition, samples that were collected from El-May’s abattoir revealed the highest bacterial counts, followed by El-Bagour and El-Shohadaa, respectively. Regarding to detection of some pathogenic bacteria in the examined swab samples, S. aureus was the most detected bacteria, followed by Salmonella spp. and E. coli with total incidence 23.3, 18.3 and 15.0, respectively. However, equal number of S. aureus isolates was obtained from neck and groin samples, groin samples showed higher incidence of Salmonella and E. coli than those of neck samples. In addition, staphylococcal enterotoxins were investigated in the contaminated samples. Results revealed that all of the examined samples had enterotoxin type A only. Moreover, E. coli isolates were serotyped into O103:H2, O146:H21 and O117:H4; out of which, three strains were molecularly examined for their Shiga toxin types 1 (stx-1) and 2 (stx-2) genes; where, stx-1 was detected in 66.7% of the examined strains, while stx-2 was not detected in any of the examined isolates. On the other hand, Salmonella strains were serotyped into S. Enteritidis, S. Montevideo, S. Tsevie, S. Typhimurium and S. Shangani were the detected serotypes. Salmonella Typhimurium was detected in higher incidence than the other detected strains. So, regular monitoring of beef carcasses microbiological evaluation, and application of strict hygienic measures are recommended. [ABSTRACT FROM AUTHOR]

[Display omitted] • Attenuated auxotrophic Salmonella Typhimurium was utilized for the anti-tumor effect. • Reduction of endotoxicity was rendered by lipid A modification. • Regulated expression of ClyA at higher cell density under QS signaling. • Engineered Salmonella Typhimurium enhanced safety and tumor invasion. • ClyA expressing Salmonella reduced 67 % of tumors in mouse CT 26 cancer model. The limitations of conventional cancer therapies necessitate target-oriented, highly invasive, and safe treatment approaches. Hence, the intrinsic anti-tumor activity of Salmonella can offer better options to combat cancers. This study aims to utilize attenuated Salmonella and deliver cytolytic protein cytolysin A (ClyA) under quorum sensing (QS) signaling for precise localized expression in tumors but not in healthy organs. The therapeutic delivery strain was imposed with tryptophan auxotroph for selective colonization in tumors by trpA and trpE deletion, and lipid-A and O-antigen were altered by pagL and rfaL deletions using lambda red recombination method. The strain was transformed with the designed QS-controlled ClyA expression vector which was validated by western blot. The in vivo passaged therapeutic strain was used for treatment four times at a weekly interval, with a dose of 5 × 106 CFU/mouse for cancer therapy. The attenuated strain induced minimal endotoxicity-related cytokines TNF-α, IL-1β, and IFN-γ and exhibited adequate colonization despite earlier exposure in mice. The QS-controlled ClyA expression was confirmed by western blot from bacterial cultures grown at different cell densities. The results demonstrated that the in vivo passaged strain preferentially colonized the tumor after vacating the spleen, liver, and lung, leaving no outward histological scars. The anti-cancer effect of the designed construct was evaluated in the murine CT26 colon cancer model. The expression of ClyA increased tumoricidal activity by 67 % compared to vector control. Hence, the anti-tumor effect of the engineered Salmonella strain was improved by ClyA expression via QS activation after achieving the threshold bacterial cell density. Further, immunohistochemical staining of the tumor and other organs corroborated the QS-controlled tumor-specific expression of ClyA. Overall, the results imply that the developed anti-cancer Salmonella has low endotoxicity and QS-controlled expression of ClyA as beneficial safety elements and supports recurrent Salmonella inoculation by O-antigen deficiency. [ABSTRACT FROM AUTHOR]

Glycoconjugation is a well-established technology for vaccine development: linkage of the polysaccharide (PS) antigen to an appropriate carrier protein overcomes the limitations of PS T-independent antigens, making them effective in infants and providing immunological memory. Glycoconjugate vaccines have been successful in reducing the burden of different diseases globally. However, many pathogens still require a vaccine, and many of them display a variety of glycans on their surface that have been proposed as key antigens for the development of high-valency glycoconjugate vaccines. CDAP chemistry represents a generic conjugation strategy that is easily applied to PS with different structures. This chemistry utilizes common groups to a large range of PS and proteins, e.g., hydroxyl groups on the PS and amino groups on the protein. Here, new fast analytical tools to study CDAP reaction have been developed, and reaction conditions for PS activation and conjugation have been extensively investigated. Mathematical models have been built to identify reaction conditions to generate conjugates with wanted characteristics and successfully applied to a large number of bacterial PSs from different pathogens, e.g., Klebsiella pneumoniae, Salmonella Paratyphi A, Salmonella Enteritidis, Salmonella Typhimurium, Shighella sonnei and Shigella flexneri. Furthermore, using Salmonella Paratyphi A O-antigen and CRM197 as models, a design of experiment approach has been used to study the impact of conjugation conditions and conjugate features on immunogenicity in rabbits. The approach used can be rapidly extended to other PSs and accelerate the development of high-valency glycoconjugate vaccines. [ABSTRACT FROM AUTHOR]

Salmonella enterica Typhimurium DT104 (S. Typhimurium DT104) is an important foodborne pathogen that is associated with poultry and poultry products. Currently, there is very little information on the underlying molecular mechanisms that allow DT104 to survive and propagate in poultry meat and the poultry processing environment. The current study assessed the global gene expression of DT104 in ground chicken extract (GCE) compared to brain heart infusion (BHI) medium using RNA-Seq technology. DT104 was grown to the early stationary phase (ESP), inoculated into GCE or BHI, and then re-grown to the log phase before RNA was extracted and transcripts were quantified by RNA-Seq. Gene expression for DT104 grown in GCE was then compared to that of DT104 grown in BHI for samples grown to the ESP. Growth in GCE resulted in the up-regulated expression of genes related to translation, carnitine metabolism (23–283-fold change), and cobalamin (vitamin B12) biosynthesis (14-fold change). In particular, the presence of carnitine in chicken meat, and thus, in GCE, which lacks carbohydrates, may allow Salmonella to utilize this compound as a carbon and nitrogen source. This study demonstrates that RNA-Seq data can provide a comprehensive analysis of DT104 gene expression in a food model for poultry products. This study also provides additional evidence for the importance of metabolic adaptation in the ability of S. enterica to successfully adapt to and occupy niches outside of its host and provides potential targets that could be used to develop intervention strategies to control Salmonella in poultry. [ABSTRACT FROM AUTHOR]

Salmonella typhimurium (S. typhimurium) is one of the most common Salmonella serotypes in epidemiological surveys of poultry farms in recent years. It causes growth retardation, mortality, and significant economic losses. The extensive use of antibiotics has led to the emergence of multi-drug resistance (MDR) in Salmonella, which has become a significant global problem and long-term challenge. In this study, we investigated the prevalence and features of S. typhimurium strains in duck embryos and cloacal swabs from large-scale duck farms in Shandong, China, including drug resistance and virulence genes and the pathogenicity of an S. typhimurium strain by animal experiment. The results demonstrated that a total of 8 S. typhimurium strains were isolated from 13,621 samples. The drug resistance results showed that three of the eight S. typhimurium strains were MDR with the dominant resistance profile of CTX-DX-CTR-TE-AMX-AMP-CAZ. In particular, the virulence genes invA, hilA, pefA, rck, and sefA showed high positive rates. Based on the analysis of the biological characteristics of bacterial biofilm formation and mobility, a strain of S. typhimurium with the strongest biofilm formation ability, designated 22SD07, was selected for animal infection experiments with broiler ducklings. The results of animal experiments demonstrated that infection with 22SD07 reduced body weight and bursa index but increased heart and liver indexes compared to the control group. Histological examination revealed desquamation of the intestinal villous epithelium, the presence of large aggregates of lymphocytes, and a decrease in goblet cells following infection. Furthermore, the expression of IL-10 was significantly increased in the liver at 3 dpi, while TNF-α was significantly increased in the spleen at 7 dpi. The above results indicate that S. typhimurium may pose a potential threat to human health through the food chain. This helps us to understand the frequency and characteristics of S. typhimurium in duck farms and emphasizes the urgent need to strengthen and implement effective continuous monitoring to control its infection and transmission. [ABSTRACT FROM AUTHOR]

Pathogenic Salmonella strains causing gastroenteritis typically can colonize and proliferate in the intestines of multiple host species. They retain the ability to form red dry and rough (rdar) biofilms, as seen in Salmonella enterica serovar Typhimurium. Conversely, Salmonella serovar like Typhi, which can cause systemic infections and exhibit host restriction, are rdar-negative. In this study, duck-derived strains and swine-derived strains of S. Typhimurium locate on independent phylogenetic clades and display relative genomic specificity. The duck isolates appear more closely related to human blood isolates and invasive non-typhoidal Salmonella (iNTS), whereas the swine isolates were more distinct. Phenotypically, compared to duck isolates, swine isolates exhibited enhanced biofilm formation that was unaffected by the temperature. The transcriptomic analysis revealed the upregulation of csgDEFG transcription as the direct cause. This upregulation may be mainly attributed to the enhanced promoter activity caused by the G-to-T substitution at position −44 of the csgD promoter. Swine isolates have created biofilm polymorphisms by altering a conserved base present in Salmonella Typhi, iNTS, and most Salmonella Typhimurium (such as duck isolates). This provides a genomic characteristics perspective for understanding Salmonella transmission cycles and evolution. [ABSTRACT FROM AUTHOR]