Pilus Gene Research Articles

Surveillance of travel-associated isolates elucidates the diversity of non-pandemic Vibrio cholerae.

Vibrio cholerae is a Gram-negative bacterium found in aquatic environments and is the aetiological agent of cholera, characterized by acute watery diarrhoea and severe dehydration. Cholera presents a significant global health burden of an estimated 1.3-5 million annual cases, with the current pandemic caused by a toxigenic lineage of the O1 El Tor biotype called seventh pandemic El Tor (7PET) that is still ongoing. Whilst it is known that non-7PET lineages can cause sporadic disease, little is known about the transmission of these non-epidemic lineages. Thirty-four V. cholerae isolates were obtained from travellers returning from Indonesia to Australia between 2005 and 2017. These were whole genome sequenced, placed into a global phylogenetic context with 883 isolates, and screened for known genes associated with antimicrobial resistance and virulence. This analysis revealed that 30 isolates fell within non-7PET lineages and four within the 7PET lineage. Both 7PET and non-7PET isolates carried genes for resistance to antibiotics that are commonly used in cholera treatment such as tetracyclines and fluoroquinolones. Diverse virulence factors were also present in non-7PET isolates, with two isolates notably carrying toxin-coregulated pilus genes, which are primarily responsible for intestinal colonization in 7PET V. cholerae. This study demonstrates the role of travel in long-range carriage of epidemic and non-epidemic lineages of V. cholerae, and how sentinel travel surveillance can enrich our knowledge of V. cholerae diversity, reveal new biology about the spread of diverse lineages with differing disease potential and illuminate disease presence in endemic regions with limited surveillance data.

Integrating the independent granular charge carriers into microbial fuel cell: From performance to mechanism analysis

The mutual benefits between electroactive bacteria (EAB) and non-EAB promote bioenergy recovery in microbial fuel cell (MFC), while competition between functional and non-functional bacteria on electrodes hinders further performance improvement. Introducing non-electrode conductive carriers into MFC may reduce contact resistance and alleviate interspecies competition. In this study, three-dimensional spherical biochar (BC) granules as independent microbial and charge carriers are introduced into anode chamber of an MFC without direct contact with the electrode (carbon cloth, CC) creating CC-BC-MFC. CC-BC-MFC achieves superior power density of 15 ± 1.4 W m−3 compared to CC-MFC (12 ± 1.4 W m−3) and CC/BC-MFC (10 ± 1.2 W m−3, where BC directly contacts CC). Higher effluent quality highlights the outstanding contribution of adequate biomass in effective containment treatment. Smaller internal resistance and higher coulombic efficiency are obtained in CC-BC-MFC by relieving microbial competition at anode. Syntrophic growth between Geobacter (69.4 %) and Methanosarcina (98 %) is established on BC in CC-BC-MFC, with high expression of Geobacter-associated pili genes and acetotrophic and CO2-reducing methanogenic genes associated with methanogens. Therefore, incorporating BC as flexible and independent charge carriers can reduce internal resistance, provide adequate habitat, alleviate microbial competition at anode, and offer a feasible strategy for MFC in wastewater treatment.

Isolate and Molecular Identification of Bundle Forming Pilus Gene for Escherichia coli Caused Caw Mastitis

Mastitis is one of the disease infected Caws and effect of their milk product lead economic loss. The aim of this study isolated and molecular identification Bundle Forming Pilus Gene for Escherichia coli caused Caw mastitis. Samples were collected from Caws infected with Mastitis at different farm in Iraq, then applied for cultivation on the suitable media for isolated of E. coli. The E.coli isolates was confirmed by VITEK II automated microbial identification system method and identification by PCR method for expression of bundle forming pilus gene. The result was shown that (9 from 100) from mastitis cases give E. coli positive. All E.coli isolates were confirmed by VITEK method. All E.coli isolates were expressed of bundle forming pilus gene. Conclusion: E.coli caused severe mastitis in Caw and the severity of infection come from express of bundle forming pilus gene that increases the virulence of E.coli be more resistance to antibiotics and unsuitable conditions that may be lead to many serious diseases if dietary contaminated with mastitis E.coli .

Expression of Pili Genes (ebpA and ebpC) Associated with Multi Drug Resistant Enterococcus faecalis Isolates

The antibiotic susceptibility was determined for 118 clinical E. faecalis isolates , the isolates showed various levels of susceptibilities to different antibiotics and 70.5% of these isolates were multidrug resistant. The relative expression of ebpA gene in six multidrug resistance E. faecalis isolates was determined in comparison with antibiotic-sensitive isolates selected as a control sample. The isolate 21 from root canal (multi drug resistance) showed increasing in expression in comparison with antibiotic sensitive isolates of E. faecalis. The relative expression of ebpC gene in multidrug resistance E. faecalis isolates was determined in comparison with antibiotic sensitive isolates which were selected as control samples. The isolate 21 from root canal and the isolates 19 from urine (multi drug resistance) showed high expression in comparison with antibiotic sensitive isolates of E. faecalis. The expression of ebpA and ebpC genes in multi drug resistance isolates in relation to their sources showed that urine group gave a high rate of expression of ebpC followed by root canal in comparison with ebpA expression. In contrast, the vagina group gave a higher expression of ebpA than ebpC. The findings of the present investigation revealed a significant correlation (P=0.05) between the multi-drug resistance and gene expression of ebpA gene, while there is no significant (P=0.05) correlation with ebpC.

High prevalence of the recently identified clonal lineage ST1299/CT3109 vanA among vancomycin-resistant Enterococcus faecium strains isolated from municipal wastewater.

Previously, we demonstrated that the majority of vancomycin-resistant Enterococcus faecium (VREfm) strains from in-patients of the University Hospital Erlangen, Germany, belonged to only three clonal lineages, namely ST117/CT71 vanB and two novel ST1299 vanA lineages classified as CT3109 and CT1903. The goal of the current study was (i) to investigate whether VREfm is also detectable in wastewater of the city of Erlangen, (ii) to identify their molecular features, and (iii) to clarify whether VREfm could arise from the community of the city of Erlangen or can be (directly) connected to nosocomial infections in the hospital setting. From April to May 2023, a total of 244 VREfm strains from raw wastewater of the city of Erlangen were analyzed by core genome multilocus sequence typing (cgMLST). Moreover, 20 of them were further investigated for single nucleotide polymorphisms (SNPs). The molecular characterization of the wastewater VREfm strains revealed a high prevalence (27.9%) of the recently identified clonal lineage ST1299/CT3109 vanA, which is mainly characterized by the presence of the tetracycline-resistance determinant tet(M) and the virulence genes pilA and prpA. The SNPs analysis revealed the presence of two major clusters, namely cluster I (≤65 SNPs), which included well-known hospital-adapted vanB clonal lineages such as ST117/CT71 and ST80/CT1065 and cluster II (≤70 SNPs), which were mainly characterized by the lineage ST1299/CT3109 vanA. Based on the concomitant resistance to vancomycin and tetracycline, we propose that ST1299/CT3109 vanA primarily originated and spread outside of hospital settings.IMPORTANCEThis study provides a detailed genomic analysis of vancomycin-resistant Enterococcus faecium (VREfm) strains isolated from municipal wastewater with a particular focus on clonal lineages, antimicrobial resistance, and the presence of virulence genes. The high wastewater prevalence of the recently identified clonal lineage ST1299/CT3109 vanA, which has been previously detected in hospitals, suggests an enormous potential for future spread in Germany.

Ethanol-type anaerobic digestion enhanced methanogenic performance by stimulating direct interspecies electron transfer and interspecies hydrogen transfer

Ethanol pre-fermentation of food waste effectively alleviates acidification; however, its effects on interspecies electron transfer remain unknown. This study configured the feed according to COD ratios of ethanol: sodium acetate: sodium propionate: sodium butyrate of 5:2:1.5:1.5 (ethanol-type anaerobic digestion) and 0:5:2.5:2.5 (control), and conducted semi-continuous anaerobic digestion (AD) experiments. The results showed that ethanol-type AD increased maximum tolerable organic loading rate (OLR) to 6.0 gCOD/L/d, and increased the methane production by 1.2–14.8 times compared to the control at OLRs of 1.0–5.0 gCOD/L/d. The abundance of the pilA gene, which was associated with direct interspecies electron transfer (DIET), increased by 5.6 times during ethanol-type AD. Hydrogenase genes related to interspecies hydrogen transfer (IHT), including hydA-B, hoxH-Y, hnd, ech, and ehb, were upregulated during ethanol-type AD. Ethanol-type AD improved methanogenic performance and enhanced microbial metabolism by stimulating DIET and IHT.

Differential effects of GAC and graphite on interspecies electron transfer during anaerobic digestion of waste activated sludge for methane production

This study investigated the effect of the particle size of granular activated carbon (GAC) and graphite on methane production efficiency. Additionally, differences in the mechanisms by which GAC and graphite-enhanced anaerobic digestion (AD) of waste activated sludge (WAS) were evaluated. The results showed that 150 μm GAC and 38 μm graphite had the best promoting effect, increasing cumulative biogas production by 14.6 % and 12.3 %, respectively, compared with blank control. GAC advanced the peak daily biogas production to day 8. Scanning electron microscopy revealed the formation of a dense bacterial biofilm on the GAC surface. Microorganisms on the graphite surface had more conductive pili than those on the GAC and blank surfaces. GAC enriched Methanobacterium (hydrogenotrophic methanotrophic archaea) while maintaining the relative abundance of existing acetate methanogenic bacteria. Conversely, graphite reduced the abundance of hydrogenotrophic methanogenic bacteria and enriched Methanosaeta, which participate in direct interspecies electron transfer. GAC increased the abundance of key enzymes in the hydrogenotrophic methanogenesis pathway and alleviated the inhibition of nitrate nitrogen and H2 in the methanogenesis reaction system. In contrast, graphite increased the abundance of pili genes and promoted electron exchange between symbiotic bacteria and methanogens, thereby accelerating substrate consumption and methane production.

Upstream CtrA-binding sites both induce and repress pilin gene expression in Caulobacter crescentus

Pili are bacterial surface structures important for surface adhesion. In the alphaproteobacterium Caulobacter crescentus, the global regulator CtrA activates transcription of roughly 100 genes, including pilA which codes for the pilin monomer that makes up the pilus filament. While most CtrA-activated promoters have a single CtrA-binding site at the − 35 position and are induced at the early to mid-predivisional cell stage, the pilA promoter has 3 additional upstream CtrA-binding sites and it is induced at the late predivisional cell stage. Reporter constructs where these additional sites were disrupted by deletion or mutation led to increased activity compared to the WT promoter. In synchronized cultures, these mutations caused pilA transcription to occur approximately 20 min earlier than WT. The results suggested that the site overlapping the − 35 position drives pilA gene expression while the other upstream CtrA-binding sites serve to reduce and delay expression. EMSA experiments showed that the − 35 Site has lower affinity for CtrA∼P compared to the other sites, suggesting binding site affinity may be involved in the delay mechanism. Mutating the upstream inhibitory CtrA-binding sites in the pilA promoter caused significantly higher numbers of pre-divisional cells to express pili, and phage survival assays showed this strain to be significantly more sensitive to pilitropic phage. These results suggest that pilA regulation evolved in C. crescentus to provide an ecological advantage within the context of phage infection.

Functional Analysis of the Major Pilin Proteins of Type IV Pili in Streptococcus sanguinis CGMH010.

The pil gene cluster for Type IV pilus (Tfp) biosynthesis is commonly present and highly conserved in Streptococcus sanguinis. Nevertheless, Tfp-mediated twitching motility is less common among strains, and the factors determining twitching activity are not fully understood. Here, we analyzed the functions of three major pilin proteins (PilA1, PilA2, and PilA3) in the assembly and activity of Tfp in motile S. sanguinis CGMH010. Using various recombinant pilA deletion strains, we found that Tfp composed of different PilA proteins varied morphologically and functionally. Among the three PilA proteins, PilA1 was most critical in the assembly of twitching-active Tfp, and recombinant strains expressing motility generated more structured biofilms under constant shearing forces compared to the non-motile recombinant strains. Although PilA1 and PilA3 shared 94% identity, PilA3 could not compensate for the loss of PilA1, suggesting that the nature of PilA proteins plays an essential role in twitching activity. The single deletion of individual pilA genes had little effect on the invasion of host endothelia by S. sanguinis CGMH010. In contrast, the deletion of all three pilA genes or pilT, encoding the retraction ATPase, abolished Tfp-mediated invasion. Tfp- and PilT-dependent invasion were also detected in the non-motile S. sanguinis SK36, and thus, the retraction of Tfp, but not active twitching, was found to be essential for invasion.

VirulenceFinder for Enterococcus faecium and Enterococcus lactis: an enhanced database for detection of putative virulence markers by using whole-genome sequencing data.

Enterococcus faecium (Efm) is a leading cause of hospital-associated (HA) infections, often enriched in putative virulence markers (PVMs). Recently, the Efm clade B was assigned as Enterococcus lactis (Elts), which usually lack HA-Efm infection markers. Available databases for extracting PVM are incomplete and/or present an intermix of genes from Efm and Enterococcus faecalis, with distinct virulence profiles. In this study, we constructed a new database containing 27 PVMs [acm, scm, sgrA, ecbA, fnm, sagA, hylEfm, ptsD, orf1481, fms15, fms21-fms20 (pili gene cluster 1, PGC-1), fms14-fms17-fms13 (PGC-2), empA-empB-empC (PGC-3), fms11-fms19-fms16 (PGC-4), ccpA, bepA, gls20-glsB1, and gls33-glsB] from nine reference genomes (seven Efm + two Elts). The database was validated against these reference genomes and further evaluated using a collection of well-characterized Efm (n = 43) and Elts (n = 7) control strains, by assessing PVM presence/absence and its variants together with a genomic phylogeny constructed as single-nucleotide polymorphisms. We found a high concordance between the phylogeny and in silico findings of the PVM, with Elts clustering separately and mostly carrying Elts-specific PVM gene variants. Based on our validation results, we recommend using the database with raw reads instead of assemblies to avoid missing gene variants. This newly constructed database of 27 PVMs will enable a more comprehensive characterization of Efm and Elts based on WGS data. The developed database exhibits scalability and boasts a range of applications in public health, including diagnostics, outbreak investigations, and epidemiological studies. It can be further used in risk assessment for distinguishing between safe and unsafe enterococci.IMPORTANCEThe newly constructed database, consisting of 27 putative virulence markers, is highly scalable and serves as a valuable resource for the comprehensive characterization of these closely related species using WGS data. It holds significant potential for various public health applications, including hospital outbreak investigations, surveillance, and risk assessment for probiotics and feed additives.

The key metabolic pathway for enhanced anaerobic digestion of chicken manure with coal slime for methane production

Coal slime can significantly enhance anaerobic digestion (AD) of chicken manure (CM) for methane production; However, the underlying mechanism is still unclear. This study has mainly discussed variation characteristics of key metabolic pathways in the AD process of CM by coal slime. Dry CM and coal slime (CS) were selected and coal seam mine water was applied as bacteria source. CS effects on the metabolic pathway of CM fermentation system were studied by biogas production simulation experiments and metagenomic analyses. The results indicated that variations in pH and CS amount exerted significant effects on the biogas generation in the contest of CM fermentation. Optimal conditions for enhanced biogas production were observed when the pH approached neutrality, and the CS quantity was 0.2 g, highlighting substantial potential of CM for biogas generation. The addition of CS resulted in a 13.1%, 1.9%, and 1.8% increase in the relative abundance of Bacteroides, Aminobacterium, and Methanothrix. This, in turn, elevated gene abundance of essential enzymes in the glycolytic pathway (glycolysis and pyruvate metabolism), promoting acetic acid production and providing a foundational basis for methanogen metabolic gas production. Furthermore, the addition of CS lead to a notable increase in the abundance of the pilA gene in Methanocorpusculuma (111.5%) and Methanothrix (66.1%). This suggested the involvement of CS in DIEF, thereby augmenting the anaerobic methane production potential of CM. These outcomes offer valuable theoretical insights for optimizing the biogas production potential of CM and maximizing the resource utilization of CS.

Secondary messenger signalling influences Pseudomonas aeruginosa adaptation to sinus and lung environments.

Pseudomonas aeruginosa is a cause of chronic respiratory tract infections in people with cystic fibrosis (CF), non-CF bronchiectasis, and chronic obstructive pulmonary disease. Prolonged infection allows the accumulation of mutations and horizontal gene transfer, increasing the likelihood of adaptive phenotypic traits. Adaptation is proposed to arise first in bacterial populations colonizing upper airway environments. Here, we model this process using an experimental evolution approach. Pseudomonas aeruginosa PAO1, which is not airway adapted, was serially passaged, separately, in media chemically reflective of upper or lower airway environments. To explore whether the CF environment selects for unique traits, we separately passaged PAO1 in airway-mimicking media with or without CF-specific factors. Our findings demonstrated that all airway environments-sinus and lungs, under CF and non-CF conditions-selected for loss of twitching motility, increased resistance to multiple antibiotic classes, and a hyper-biofilm phenotype. These traits conferred increased airway colonization potential in an in vivo model. CF-like conditions exerted stronger selective pressures, leading to emergence of more pronounced phenotypes. Loss of twitching was associated with mutations in type IV pili genes. Type IV pili mediate surface attachment, twitching, and induction of cAMP signalling. We additionally identified multiple evolutionary routes to increased biofilm formation involving regulation of cyclic-di-GMP signalling. These included the loss of function mutations in bifA and dipA phosphodiesterase genes and activating mutations in the siaA phosphatase. These data highlight that airway environments select for traits associated with sessile lifestyles and suggest upper airway niches support emergence of phenotypes that promote establishment of lung infection.

Associations of motility and auto-aggregation with biofilm-formation capacity levels in Clostridioidesdifficile

Clostridioides difficile (C. difficile) is responsible for one of the most common nosocomial infections worldwide. This work assessed associations between biofilm-formation capacity levels of C. difficile and cell viability, motility, flagella, motility and auto-aggregation in 118 clinical isolates. Biofilm production was assessed by the crystal violet method. Cell viability was determined by BacTiter-Glo™ Microbial Cell Viability Assay and live-imaging microscopy. Expression levels of LuxS, Cwp84, Spo0A, PilA, and FliC were measured by real-time PCR. Motility was visually assessed in agar tubes. Auto-aggregation levels were determined by OD600 measurements. Out of 118 isolates, 66 (56 %) were biofilm producers, with most being strong or moderate producers. Cell viability, motility and auto-aggregation positively correlated with biofilm-production capacity (p = 0.0001, p = 0.036 and p < 0.0001, respectively). Positive associations were found between pilA, fliC and luxS expression levels and biofilm-production capacity (p = 0.04, p = 0.01, p = 0.036, respectively). This is the first report of associations between biofilm-formation capacity and cell viability, pilA, fliC, and luxS gene expression, auto-aggregation and motility. These correlations should be further explored to expand knowledge on the regulation of C. difficile biofilm formation, and pathogenesis, which will have notable implications on treatment options.

Acidovorax citrulli Type IV Pili PilR Interacts with PilS and Regulates the Expression of the pilA Gene

Acidovorax citrulli can cause bacterial fruit blotch of watermelon, melon, and other cucurbits, and has the potential to cause severe economic losses to growers throughout the world. This article investigated the functions and interactions of the pilR and pilS genes, two important genes in bacterial type IV pili systems, in A. citrulli. For each gene, deletion mutants and complementary strains were constructed via homologous recombination, and their phenotypes were determined. The results showed that the absence of pilR and pilS could significantly reduce the pathogenicity and twitching motility of A. citrulli while increasing the swimming motility, biofilm formation, and in vitro growth. Conversely, complementary strains were no different than the wild-type strain. Using quantitative reverse transcription PCR and promoter activity assays, we confirmed that the deletion of pilR and pilS genes leads to a significant decrease in the transcription level of pilA. Meanwhile, three methods including yeast two-hybrid, glutathione S-transferase pull-down, and luciferase complementation imaging assays were used to verify the direct interaction between the PilR and PilS proteins. These findings revealed the biological function of the pilR and pilS and confirms their regulatory role on pilA.

Enhanced coal biomethanation by microbial electrolysis and graphene in the anaerobic digestion

The combination of microbial electrolytic cells and conductive materials can effectively promote direct interspecies electron transfer (DIET) to increase methane production, which has great potential for enhanced anaerobic degradation of organic matter. A single-chamber microbial electrolytic cell containing graphene was constructed using long-flame coal as a substrate. The results showed that the external electric field and graphene increased the abundance of hydrolytic bacteria (Paraclostridium, Sedimentibacter) and hydrogen-producing acetogenic bacteria (Anaerovorax) in the AD system. The consumption rate of alkanes, volatile fatty acids and alcohols was accelerated, which provided sufficient nutrients for methanogens and increased biomethane production by 53.1 %. The abundance of related genes involved in the carbon dioxide reduction pathway was significantly increased. The abundance of pilA gene involved in electron transport in the AD system increased by 153.7 %, and the abundance of electroactive microorganisms Geobacter and Methanosarcina capable of DIET increased significantly, which further promoted coal biomethanation.

Disease burden, antimicrobial resistance and molecular characterization of invasive group B Streptococcus among non-pregnant adults in Malaysia: A protocol study

Objective: To determine the prevalence of group B Streptococcus (GBS) isolated from non-pregnant adults from seven major hospitals in Peninsular Malaysia; the incidence, case-fatality ratio, antimicrobial susceptibility patterns, serotype, genotype and distribution of the GBS virulence and pili genes are also investigated. Methods: This multicentre, prospective, observational study is conducted in seven major tertiary hospitals in Malaysia among non-pregnant adults. Simultaneously, a retrospective study is conducted in the selected hospitals with similar approaches. GBS isolates are subjected to phenotyping, serotyping by multiplex PCR, antimicrobial susceptibility testing and PCR-detection of GBS virulence and pilus genes. Seven housekeeping genes are amplified and sequenced for multi-locus sequence typing. Discussion: Findings from the study may contribute to the management of clinical practice to diagnose and prevent GBS related diseases in a timely manner. Prudent use of antibiotics is encouraged by monitoring antimicrobial resistance.

Autoinducer-2 promotes adherence of Aeromonas veronii through facilitating the expression of MSHA type IV pili genes mediated by c-di-GMP.

Aeromonas veronii can adhere to host cells through different adherence factors including outer-membrane proteins (OMPs), lipopolysaccharide (LPS), and pili, but its adherence mechanisms are still unclear. Here, we evaluated the effect of autoinducer-2 (AI-2) on adherence of A. veronii and its regulation mechanism. After determination of the promotion effect of AI-2 on adherence, we investigated which adherence factor was regulated by AI-2, and the results show that AI-2 only limits the formation of pili. Among the four distinct pili systems, only the mannose-sensitive hemagglutinin (MSHA) type IV pili genes were significantly downregulated after deficiency of AI-2. MshE, an ATPase belonged to MSHA type IV pilin, was confirmed as c-di-GMP receptor, that can bind with c-di-GMP which is positively regulated by AI-2, and the increase of c-di-GMP can promote the expression of MSHA type IV pili genes and adherence of A. veronii. Therefore, this study confirms that c-di-GMP positively regulated by AI-2 binds with MshE, then increases the expression of MSHA pili genes, finally promoting adherence of A. veronii, suggesting a multilevel positive regulatory adhesion mechanism that is responsible for A. veronii adherence.

The Clinical and Genetic Characteristics of Streptococcus agalactiae Meningitis in Neonates.

Streptococcus agalactiae (Group B Streptococcus, GBS) is an important pathogen of bacterial meningitis in neonates. We aimed to investigate the clinical and genetic characteristics of neonatal GBS meningitis. All neonates with GBS meningitis at a tertiary level medical center in Taiwan between 2003 and 2020 were analyzed. Capsule serotyping, multilocus sequence typing, antimicrobial resistance, and whole-genome sequencing (WGS) were performed on the GBS isolates. We identified 48 neonates with GBS meningitis and 140 neonates with GBS sepsis. Neonates with GBS meningitis had significantly more severe clinical symptoms; thirty-seven neonates (77.8%) had neurological complications; seven (14.6%) neonates died; and 17 (41.5%) survivors had neurological sequelae at discharge. The most common serotypes that caused meningitis in neonates were type III (68.8%), Ia (20.8%), and Ib (8.3%). Sequence type (ST) is highly correlated with serotypes, and ST17/III GBS accounted for more than half of GBS meningitis cases (56.3%, n = 27), followed by ST19/Ia, ST23/Ia, and ST12/Ib. All GBS isolates were sensitive to ampicillin, but a high resistance rates of 72.3% and 70.7% to erythromycin and clindamycin, respectively, were noted in the cohort. The virulence and pilus genes varied greatly between different GBS serotypes. WGS analyses showed that the presence of PezT; BspC; and ICESag37 was likely associated with the occurrence of meningitis and was documented in 60.4%, 77.1%, and 52.1% of the GBS isolates that caused neonatal meningitis. We concluded that GBS meningitis can cause serious morbidity in neonates. Further experimental models are warranted to investigate the clinical and genetic relevance of GBS meningitis. Specific GBS strains that likely cause meningitis requires further investigation and clinical attention.

Lactiplantibacillus plantarum Postbiotics Suppress Salmonella Infection via Modulating Bacterial Pathogenicity, Autophagy and Inflammasome in Mice.

Our study aimed to explore the effects of postbiotics on protecting against Salmonella infection in mice and clarify the underlying mechanisms. Eighty 5-week-old C57BL/6 mice were gavaged daily with Lactiplantibacillus plantarum (LP)-derived postbiotics (heat-killed bacteria, LPBinactive; culture supernatant, LPC) or the active bacteria (LPBactive), and gavaged with Salmonella enterica Typhimurium (ST). The Turbidimetry test and agar diffusion assay indicated that LPC directly inhibited Salmonella growth. Real-time PCR and biofilm inhibition assay showed that LPC had a strong ability in suppressing Salmonella pathogenicity by reducing virulence genes (SopE, SopB, InvA, InvF, SipB, HilA, SipA and SopD2), pili genes (FilF, SefA, LpfA, FimF), flagellum genes (FlhD, FliC, FliD) and biofilm formation. LP postbiotics were more effective than LP on attenuating ST-induced intestinal damage in mice, as indicated by increasing villus/crypt ratio and increasing the expression levels of tight junction proteins (Occludin and Claudin-1). Elisa assay showed that LP postbiotics significantly reduced ST-induced inflammation by regulating the levels of inflammatory cytokines (the increased IL-4 and IL-10 and the decreased TNF-α) in serum and ileum (p < 0.05). Furthermore, LP postbiotics inhibited the activation of NOD-like receptor thermal protein domain-associated protein 3 (NLRP3) inflammasome by decreasing the protein expression of NLRP3 and Caspase-1, and the gene expression of Caspase-1, IL-1β and IL-18. Meanwhile, both LPC and LPB observably activated autophagy under ST infection, as indicated by the up-regulated expression of LC3 and Beclin1 and the downregulated p62 level (p < 0.05). Finally, we found that LP postbiotics could trigger an AMP-activated protein kinase (AMPK) signaling pathway to induce autophagy. In summary, Lactiplantibacillus plantarum-derived postbiotics alleviated Salmonella infection via modulating bacterial pathogenicity, autophagy and NLRP3 inflammasome in mice. Our results confirmed the effectiveness of postbiotics agents in the control of Salmonella infection.

The host specificity of pilus gene traA in Escherichia coli and its use in tracking human fecal pollution

A reliable and accurate fecal source tracking (FST) approach is important in water quality management and preventing foodborne and waterborne diseases. In this study, a genetic marker of Escherichia coli (E. coli) was identified and utilized to differentiate between human and animal sources of fecal contamination. Nucleotide polymorphisms of 14 genes coding for cellular surface proteins, mainly fimbriae, were analyzed using the 22 draft genomes of E. coli strains from human and three domestic animal sources in Japan. A signature sequence, traAh, within the pilin gene traA, was found to be highly associated with E. coli of human origin. Subsequently, an end-point polymerase chain reaction (PCR) assay, namely PCR-Htra, was developed, specifically targeting traAh. The high association between traAh and E. coli of human origin was validated through the PCR-Htra amplification. This encompassed 1045 E. coli strains isolated from surface water, human feces or sewages, and feces from 12 animal species, including domestic and wild animals in the states of Missouri and Virginia in the United States of America (USA). The data suggested that the sensitivity and specificity of PCR-Htra assay were 49.0 % and 99.5 % respectively in distinguishing human-origin E. coli from nonhuman-source ones. Furthermore, the result of our in silico analysis of GenBank® data suggests that traAh may have a global distribution as the sequence was found in human-origin E. coli isolated from at least 14 countries around the world. Thus, the PCR-Htra may provide a new FST tool for rapid and accurate detection of human-origin E. coli, serving as a means to identify human fecal contamination in water.