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CprA is a short-chain dehydrogenase/reductase (SDR) that contributes to resistance against colistin and antimicrobial peptides. The cprA gene is conserved across Pseudomonas aeruginosa clades and its expression is directly regulated by the two-component system PmrAB. We have shown that cprA expression leads to the production of outer membrane vesicles (OMVs) that block autophagic flux and have a greater capacity to activate the non-canonical inflammasome pathway. In a murine model of sepsis, a P. aeruginosa strain deleted for cprA was less virulent than the wild-type (WT) strain. These results demonstrate the important role of CprA in the pathogenicity of P. aeruginosa. It is worth noting that CprA is also a functional ortholog of hemolysin F (HlyF), which is encoded by virulence plasmids of Escherichia coli. We have shown that other cryptic SDRs encoded by mammalian and plant pathogens, such as Yersinia pestis and Ralstonia solanacearum are functional orthologs of CprA and HlyF. These SDRs also induce the production of OMVs which block autophagic flux. This study uncovers a new family of virulence determinants in Gram-negative bacteria, offering potential for innovative therapeutic interventions and deeper insights into bacterial pathogenesis., (© 2025 The Author(s). Journal of Extracellular Vesicles published by Wiley Periodicals LLC on behalf of International Society for Extracellular Vesicles.)

In densely populated urban areas, the pressure on water resources is considerable and will tend to intensify over the next decades. Preserving water resources therefore seems fundamental, but many questions remain as to the transfer of contaminants to subsurface waters in these largely sealed areas. Because of their toxicity and persistence in the environment, this work focused on the study of polycyclic aromatic hydrocarbons (PAHs), ubiquitous pollutants mainly produced by human activities. To better understand the main factors leading to the retention or transport of these pollutants in urban environments, vertical transects, from the surface to several meters down, were established on three study sites in or near Paris (France), selected according to an urbanization gradient. Soil samples collected at the surface and urban secondary carbonate deposits (USCD), similar to cave speleothems, sampled underground in quarries and aqueducts were analyzed. As the hydrophobic properties of PAHs favor their sorption onto organic matter, the latter was also studied using organic carbon analysis and UV fluorescence spectroscopy. The USCD located closest to the urbanized surface contained high concentrations of PAHs (76.8 ± 5.3 ng g -1 ), while the USCD located at greater depth with organic soil on the surface contained the lowest amount of PAHs (2.9 ± 0.4 ng g -1 ), and no PAHs with log K OC > 5. The results highlight the predominant role played by the presence of organic topsoil at the surface in retaining and storing large amounts of PAHs (1914-2595 ng. g soil -1 ), particularly the most hydrophobic ones (i.e. 60% of the 15 PAHs are characterized by a Log K OC >5), which are also the most toxic. The lithology and thickness of the bedrock (between the surface and the USCD) also play an important role in the retention of PAHs, particularly those adsorbed on the particulate phase., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Objectives: Urinary tract infections (UTIs) are primarily caused by uropathogenic Escherichia coli (UPEC). This study aims to elucidate the role of the virulence factor HlyF in the epidemiology and pathophysiology of UTIs and investigate the dissemination of plasmids carrying the hlyF gene., Methods: An epidemiological analysis was conducted on a representative collection of 225 UPEC strains isolated from community-acquired infections. Selected hlyF+ strains were fully sequenced using a combination of Illumina and Nanopore technologies. To investigate the impact of HlyF, a murine model of UTI was utilized to compare clinical signs, bacterial loads in the bladder, kidney, and spleen, onset of bacteraemia, and inflammation through cytokine quantification among wild-type hlyF+ strains, isogenic mutants, and complemented mutants., Results: Our findings demonstrate that 20% of UPEC encode the HlyF protein. These hlyF+ UPEC strains exhibited enhanced virulence, frequently leading to pyelonephritis accompanied by bloodstream infections. Unlike typical UPEC strains, hlyF+ UPEC strains demonstrate a broader phylogroup distribution and possess a unique array of virulence factors and antimicrobial resistance genes, primarily carried by ColV-like plasmids. In the murine UTI model, expression of HlyF was linked to the UPECs' capacity to induce urosepsis and elicit an exacerbated inflammatory response, setting them apart from typical UPEC strains., Discussion: Overall, our results strongly support the notion that HlyF serves as a significant virulence factor for UPECs, and the dissemination of ColV-like plasmids encoding HlyF warrants further investigation., (Copyright © 2023 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.)

Macroautophagy is a ubiquitous homeostasis and health-promoting recycling process of eukaryotic cells, targeting misfolded proteins, damaged organelles and intracellular infectious agents. Some intracellular pathogens such as Salmonella enterica serovar Typhimurium hijack this process during pathogenesis. Here we investigate potential protein-protein interactions between host transcription factors and secreted effector proteins of Salmonella and their effect on host gene transcription. A systems-level analysis identified Salmonella effector proteins that had the potential to affect core autophagy gene regulation. The effect of a SPI-1 effector protein, SopE, that was predicted to interact with regulatory proteins of the autophagy process, was investigated to validate our approach. We then confirmed experimentally that SopE can directly bind to SP1, a host transcription factor, which modulates the expression of the autophagy gene MAP1LC3B . We also revealed that SopE might have a double role in the modulation of autophagy: Following initial increase of MAP1LC3B transcription triggered by Salmonella infection, subsequent decrease in MAP1LC3B transcription at 6h post-infection was SopE-dependent. SopE also played a role in modulation of the autophagy flux machinery, in particular MAP1LC3B and p62 autophagy proteins, depending on the level of autophagy already taking place. Upon typical infection of epithelial cells, the autophagic flux is increased. However, when autophagy was chemically induced prior to infection, SopE dampened the autophagic flux. The same was also observed when most of the intracellular Salmonella cells were not associated with the SCV (strain lacking sifA ) regardless of the autophagy induction status before infection. We demonstrated how regulatory network analysis can be used to better characterise the impact of pathogenic effector proteins, in this case, Salmonella . This study complements previous work in which we had demonstrated that specific pathogen effectors can affect the autophagy process through direct interaction with autophagy proteins. Here we show that effector proteins can also influence the upstream regulation of the process. Such interdisciplinary studies can increase our understanding of the infection process and point out targets important in intestinal epithelial cell defense., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Demeter, Jacomin, Gul, Lister, Lipscombe, Invernizzi, Branchu, Macaulay, Nezis, Kingsley, Korcsmaros and Hautefort.)

Edema disease is an often fatal enterotoxemia caused by specific strains of Shiga toxin-producing Escherichia coli (STEC) that affect primarily healthy, rapidly growing nursery pigs. Recently, outbreaks of edema disease have also emerged in France in wild boars. Analysis of STEC strains isolated from wild boars during 2013-2019 showed that they belonged to the serotype O139:H1 and were positive for both Stx2e and F18 fimbriae. However, in contrast to classical STEC O139:H1 strains circulating in pigs, they also possessed enterotoxin genes sta1 and stb, typical of enterotoxigenic E. coli. In addition, the strains contained a unique accessory genome composition and did not harbor antimicrobial-resistance genes, in contrast to domestic pig isolates. These data thus reveal that the emergence of edema disease in wild boars was caused by atypical hybrid of STEC and enterotoxigenic E. coli O139:H1, which so far has been restricted to the wildlife environment.

Colibactin is a genotoxin produced primarily by Escherichia coli harboring the genomic pks island ( pks +   E. coli ). Pks +   E. coli cause host cell DNA damage, leading to chromosomal instability and gene mutations. The signature of colibactin-induced mutations has been described and found in human colorectal cancer (CRC) genomes. An inflamed intestinal environment drives the expansion of pks +   E. coli and promotes tumorigenesis. Mesalamine (i.e., 5-aminosalycilic acid), an effective anti-inflammatory drug, is an inhibitor of the bacterial polyphosphate kinase (PPK). This drug not only inhibits the production of intestinal inflammatory mediators and the proliferation of CRC cells, but also limits the abundance of E. coli in the gut microbiota and diminishes the production of colibactin. Here, we describe the link between intestinal inflammation and colorectal cancer induced by pks +   E. coli . We discuss the potential mechanisms of the pleiotropic role of mesalamine in treating both inflammatory bowel diseases and reducing the risk of CRC due to pks +   E. coli .

This study addresses soil contamination in vegetated road shoulders with diffuse inflow of runoff. It aims (i) to characterize the spatial distribution of three metals (copper, lead, zinc) and PAHs, and (ii) to identify influencing factors for the inter-site differences. An extensive sampling campaign was carried out on forty road segments in the Paris region, targeting various distances and soil depths. Copper and zinc contamination was found to be mainly restricted to the first 30 cm from the road, where their concentrations ranged respectively between 40 and 270 mg.kg -1 , and between 150 and 950 mg.kg -1 (with a few additional extreme values related to the presence of a galvanized steel guardrail). Lead contamination was moderate (< 100 mg.kg -1 in more than 75% of the sites) and relatively uniform across the width of the shoulders. Conversely, highest PAH concentrations were found further from the road. These differences between contaminants were likely due to the varying importance of wet weather-related processes and atmospheric transport in their dispersion mechanisms. Copper and zinc concentrations correlated well with the traffic density, which alone explained ≥ 69% of the inter-site variability, whereas lead and PAHs did not exhibit such dependence. Soil organic matter was found to control the "ceiling" concentration of metals, thus limiting the maximum amounts that can be intercepted from road runoff. These results illustrate the feasibility of estimating contamination levels on road shoulders, and thus offer interesting perspectives for better consideration of the infrastructures' maintenance needs and improved routine operations., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The pks island codes for the enzymes necessary for synthesis of the genotoxin colibactin, which contributes to the virulence of Escherichia coli strains and is suspected of promoting colorectal cancer. From a collection of 785 human and bovine E. coli isolates, we identified 109 strains carrying a highly conserved pks island, mostly from phylogroup B2, but also from phylogroups A, B1 and D. Different scenarios of pks acquisition were deduced from whole genome sequence and phylogenetic analysis. In the main scenario, pks was introduced and stabilized into certain sequence types (STs) of the B2 phylogroup, such as ST73 and ST95, at the asnW tRNA locus located in the vicinity of the yersiniabactin-encoding High Pathogenicity Island (HPI). In a few B2 strains, pks inserted at the asnU or asnV tRNA loci close to the HPI and occasionally was located next to the remnant of an integrative and conjugative element. In a last scenario specific to B1/A strains, pks was acquired, independently of the HPI, at a non-tRNA locus. All the pks -positive strains except 18 produced colibactin. Sixteen strains contained mutations in clbB or clbD, or a fusion of clbJ and clbK and were no longer genotoxic but most of them still produced low amounts of potentially active metabolites associated with the pks island. One strain was fully metabolically inactive without pks alteration, but colibactin production was restored by overexpressing the ClbR regulator. In conclusion, the pks island is not restricted to human pathogenic B2 strains and is more widely distributed in the E. coli population, while preserving its functionality.

Colibactin induces DNA damage in mammalian cells and has been linked to the virulence of Escherichia coli and the promotion of colorectal cancer (CRC). By looking for mutants attenuated in the promoter activity of clbB encoding one of the key enzymes for the production of colibactin, we found that a mutant of the gene coding for the polyphosphate kinase (PPK) produced less colibactin than the parental strain. We observed this phenotype in different strains ranging from pathogens responsible for meningitis, urinary tract infection, or mouse colon carcinogenesis to the probiotic Nissle 1917. We confirmed the role of PPK by using an inhibitor of PPK enzymatic activity, mesalamine (also known as 5-aminosalicylic acid). Interestingly, mesalamine has a local anti-inflammatory effect on the epithelial cells of the colon and is used to treat inflammatory bowel disease (IBD). Upon treatment with mesalamine, a decreased genotoxicity of colibactin-producing E. coli was observed both on epithelial cells and directly on purified DNA. This demonstrates the direct effect of mesalamine on bacteria independently from its anti-inflammatory effect on eukaryotic cells. Our results suggest that the mechanisms of action of mesalamine in treating IBD and preventing CRC could also lie in the inhibition of colibactin production. All in all, we demonstrate that PPK is required for the promoter activity of clbB and the production of colibactin, which suggests that PPK is a promising target for the development of anticolibactin and antivirulence strategies. IMPORTANCE Colibactin-producing E. coli induces DNA damage in eukaryotic cells and promotes tumor formation in mouse models of intestinal inflammation. Recent studies have provided strong evidence supporting the causative role of colibactin in human colorectal cancer (CRC) progression. Therefore, it is important to understand the regulation of the production of this genotoxin. Here, we demonstrate that polyphosphate kinase (PPK) is required for the promoter activity of clbB and the production of colibactin. Interestingly, PPK is a multifunctional player in bacterial virulence and stress responses and has been proposed as a new target for developing antimicrobial medicine. We observed inhibition of colibactin production by using a previously identified PPK inhibitor (i.e., mesalamine, an anti-inflammatory drug commonly prescribed for inflammatory bowel diseases). These data brought us a new perspective on the regulatory network of colibactin production and provided us a clue for the development of anticolibactin strategies for CRC treatment/prophylaxis., (Copyright © 2020 Tang-Fichaux et al.)

Although Escherichia coli Nissle 1917 (EcN) has been used therapeutically for over a century, the determinants of its probiotic properties remain elusive. EcN produces two siderophore-microcins (Mcc) responsible for an antagonistic activity against other Enterobacteriaceae. EcN also synthesizes the genotoxin colibactin encoded by the pks island. Colibactin is a virulence factor and a putative pro-carcinogenic compound. Therefore, we aimed to decouple the antagonistic activity of EcN from its genotoxic activity. We demonstrated that the pks-encoded ClbP, the peptidase that activates colibactin, is required for the antagonistic activity of EcN. The analysis of a series of ClbP mutants revealed that this activity is linked to the transmembrane helices of ClbP and not the periplasmic peptidase domain, indicating the transmembrane domain is involved in some aspect of Mcc biosynthesis or secretion. A single amino acid substitution in ClbP inactivates the genotoxic activity but maintains the antagonistic activity. In an in vivo salmonellosis model, this point mutant reduced the clinical signs and the fecal shedding of Salmonella similarly to the wild type strain, whereas the clbP deletion mutant could neither protect nor outcompete the pathogen. The ClbP-dependent antibacterial effect was also observed in vitro with other E. coli strains that carry both a truncated form of the Mcc gene cluster and the pks island. In such strains, siderophore-Mcc synthesis also required the glucosyltransferase IroB involved in salmochelin production. This interplay between colibactin, salmochelin, and siderophore-Mcc biosynthetic pathways suggests that these genomic islands were co-selected and played a role in the evolution of E. coli from phylogroup B2. This co-evolution observed in EcN illustrates the fine margin between pathogenicity and probiotic activity, and the need to address both the effectiveness and safety of probiotics. Decoupling the antagonistic from the genotoxic activity by specifically inactivating ClbP peptidase domain opens the way to the safe use of EcN., Competing Interests: The authors have declared that no competing interests exist.

A multi drug resistant Salmonella enterica 4,[5],12:i- of sequence type 34 (monophasic S . Typhimurium ST34) is a current pandemic clone associated with livestock, particularly pigs, and numerous outbreaks in the human population. A large genomic island, termed SGI-4, is present in the monophasic Typhimurium ST34 clade and absent from other S . Typhimurium strains. SGI-4 consists of 87 open reading frames including sil and pco genes previously implicated in resistance to copper (Cu) and silver, and multiple genes predicted to be involved in mobilization and transfer by conjugation. SGI-4 was excised from the chromosome, circularized, and transferred to recipient strains of S . Typhimurium at a frequency influenced by stress induced by mitomycin C, and oxygen tension. The presence of SGI-4 was associated with increased resistance to Cu, particularly but not exclusively under anaerobic conditions. The presence of silCBA genes, predicted to encode an RND family efflux pump that transports Cu from the periplasm to the external milieu, was sufficient to impart the observed enhanced resistance to Cu, above that commonly associated with S . Typhimurium isolates. The presence of these genes resulted in the absence of Cu-dependent induction of pco genes encoding multiple proteins linked to Cu resistance, also present on SGI-4, suggesting that the system effectively limits the Cu availability in the periplasm, but did not affect SodCI-dependent macrophage survival.

Road runoff is contaminated by various micropollutants and may be treated using low impact development techniques, such as stormwater biofilters. Better understanding the processes, such as filtration, sorption and leaching, which affect pollutants in these systems is essential to reliably predicting treatment performance and optimizing system design. Field data from an in situ monitoring campaign, wherein dissolved and particulate concentrations of a wide range of micropollutants (trace metals, polycyclic aromatic hydrocarbons, bisphenol-A, alkylphenols and phthalates) were characterized in untreated road runoff and biofilter outlets for 19 rain events, are used to explore transport and retention processes. Although retention of the particulate phase of pollutants was generally quite effective, unusually high particle concentrations were observed at biofilter outlets for three winter events. Particle characterization in road runoff and outlet waters revealed that this degraded performance was due to poor filtration rather than particle erosion, which was attributed to the relative abundance of small (<10 μm) particles during this period, along with possible preferential flows. Dissolved pollutants were less effectively removed in general. To better understand this behavior, field results were combined with laboratory sorption and leaching tests. Dissolved concentrations of trace metals were shown to be influenced by organic carbon; leaching from road-originated particles may also influence their transport. Removal of the dissolved phase of organic micropollutants was limited by the contamination of the filter media, either before installation or during the first period of operation, due to emissions from construction materials., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Among the processes governing contaminant retention in soil-based Sustainable Urban Drainage Systems (SUDS), quantifying the relative contribution of particle settling and filtration requires a tracer of runoff-generated solids. Since zirconium (Zr) is a widely used geochemical invariant in pedological approaches, with few anthropogenic sources, the present investigation aims to assess whether its use may be extended to sediment identification in SUDS. High-resolution horizontal and vertical soil sampling was carried out in 11 infiltration systems, as well as in road-deposited sediment. Following elemental analysis via X-ray fluorescence spectrometry, the spatial distribution of both Zr and urban-derived metals could be determined. Zr content in sediment was found to be fairly stable and significantly lower than in soil. In most devices, Zr and metals exhibited "mirror" trends, both horizontally and vertically, i.e. a deficit of Zr could be observed in the most contaminated area. This indicated a "dilution-like" mixture of soil and sediment, the fraction of which could be calculated and appraised spatially. The vertical profiles proved the occurrence of bed filtration over 5 to 15 cm, and enabled the calibration of a simple filtration model. The uncertainties associated with the determined filter coefficient were found to be comparable to the other experimental methods - with the additional improvement that the present approach does not require water sampling., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The treatment efficiency of a vegetative filter strip and a biofiltration swale treating heavily loaded road runoff are evaluated. Concentrations measured in water drained from the two systems are compared to those in untreated road runoff collected from a reference catchment for a wide range of contaminants including organic carbon, nutrients (N and P), trace metals, and organic micropollutants (polycyclic aromatic hydrocarbons (PAH), total petroleum hydrocarbons (TPH), alkylphenols, bisphenol-A, phthalates), in both total and dissolved phases. Predominantly particulate pollutants, including Pb, Zn and PAH, were very efficiently removed (around 90%) for most events. However, poor particulate removal was observed during a winter period. Relatively few pollutants were significantly removed in the dissolved phase and observed concentration reductions tended to be lower than those of suspended solids and associated pollutants; as such, lower removals were observed for total concentrations of moderately particulate micropollutants, including bisphenol-A, alkylphenols and phthalates. In addition, some pollutants appear to be emitted from various biofilter components (filter media, drainage and lining materials), as low or negative concentration removals were observed during the first months of operation of the biofiltration swale., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Salmonella enterica serovar Typhimurium is one of approximately 2,500 distinct serovars of the genus Salmonella but is exceptional in its wide distribution in the environment, livestock, and wild animals. S Typhimurium causes a large proportion of nontyphoidal Salmonella (NTS) infections, accounting for a quarter of infections, second only to S. enterica serovar Enteritidis in incidence. S Typhimurium was once considered the archetypal broad-host-range Salmonella serovar due to its wide distribution in livestock and wild animals, and much of what we know of the interaction of Salmonella with the host comes from research using a small number of laboratory strains of the serovar (LT2, SL1344, and ATCC 14028). But it has become clear that these strains do not reflect the genotypic or phenotypic diversity of S Typhimurium. Here, we review the epidemiological record of S Typhimurium and studies of the host-pathogen interactions of diverse strains of S Typhimurium. We present the concept of distinct pathovariants of S Typhimurium that exhibit diversity of host range, distribution in the environment, pathogenicity, and risk to food safety. We review recent evidence from whole-genome sequencing that has revealed the extent of genomic diversity of S Typhimurium pathovariants, the genomic basis of differences in the level of risk to human and animal health, and the molecular epidemiology of prominent strains. An improved understanding of the impact of genome variation of bacterial pathogens on pathogen-host and pathogen-environment interactions has the potential to improve quantitative risk assessment and reveal how new pathogens evolve., (© Crown copyright 2018.)

Screening for the detection of carbapenemase-producing bacteria still encounters issues related to workflow, limit of detection, or qualitative interpretation. We developed a spectrophotometry-based version of the Carba NP phenol red assay (Nordmann et al., 2012) in a microtiter plate format, compatible with low bacterial cell counts. We were able to detect highly active carbapenemases such as KPC and IMP in 30min. A wider range of carbapenemases including OXA-48 were detected using higher inocula, still being competitive compared with currently available phenol red assays. Validation experiments of our test with a panel of 81 Enterobacteriaceae showed good performance with 93% of sensitivity and 92% of specificity. The compatibility of our routine-friendly protocol with automation offers great perspectives for high throughput screening in outbreak situations and/or in big laboratories., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Alkanes are widespread pollutants found in soil, freshwater and marine environments. Marinobacter hydrocarbonoclasticus ( Mh ) strain SP17 is a marine bacterium able to use many hydrophobic organic compounds, including alkanes, through the production of biofilms that allow their poor solubility to be overcome. This study pointed out that temperature is an environmental factor that strongly affects the biofilm formation and morphology of Mh on the model alkanes, hexadecane and paraffin. We showed that Mh biofilm formation and accumulation of intracytoplasmic inclusions are higher on solid alkanes (hexadecane at 10 °C and paraffin at 10 °C and 30 °C) than on liquid alkane (hexadecane at 30 °C) or soluble substrate (lactate at both temperatures). We also found that Mh produces more extracellular polymeric substances at 30 °C than at 10 °C on alkanes and none on lactate. We observed that bacterial length is significantly higher at 10 °C than at 30 °C on lactate and hexadecane. On paraffin, at 30 °C, the cell morphology is markedly altered by large rounded or irregularly shaped cytoplasmic inclusions. Altogether, the results showed that Mh is able to adapt and use alkanes as a carbon source, even at low temperature.

Stormwater runoff infiltration brings about some concerns regarding its potential impact on both soil and groundwater quality; besides, the fate of contaminants in source-control devices somewhat suffers from a lack of documentation. The present study was dedicated to assessing the spatial distribution of three heavy metals (copper, lead, zinc) in the surface soil of ten small-scale infiltration facilities, along with several physical parameters (soil moisture, volatile matter, variable thickness of the upper horizon). High-resolution samplings and in-situ measurements were undertaken, followed by X-ray fluorescence analyses and spatial interpolation. Highest metal accumulation was found in a relatively narrow area near the water inflow zone, from which concentrations markedly decreased with increasing distance. Maximum enrichment ratios amounted to >20 in the most contaminated sites. Heavy metal patterns give a time-integrated vision of the non-uniform infiltration fluxes, sedimentation processes and surface flow pathways within the devices. This element indicates that the lateral extent of contamination is mainly controlled by hydraulics. The evidenced spatial structure of soil concentrations restricts the area where remediation measures would be necessary in these systems, and suggests possible optimization of their hydraulic functioning towards an easier maintenance. Heterogeneous upper boundary conditions should be taken into account when studying the fate of micropollutants in infiltration facilities with either mathematical modeling or soil coring field surveys., (Copyright © 2016 Elsevier B.V. All rights reserved.)

In order to determine the relative importance of a vegetative filter strip and a biofiltration swale in a treatment train for road runoff, US EPA Storm Water Management Model was used to model infiltration and runoff from the filter strip. The model consisted of a series of subcatchments representing the road, the filter strip and the side-slopes of the swale. Simulations were carried out for different rain scenarios representing a variety of climatic conditions. In addition, a sensitivity analysis was conducted for the model's different parameters (soil characteristics and initial humidity, roughness, geometry, etc.). This exercise showed that for the system studied, the majority of road runoff is treated by the filter strip rather than the biofiltration swale, an effect observed especially during periods of low-intensity rainfall. Additionally, it was observed that the combination of infiltration of road runoff in the filter strip and direct rainfall on the system leads to a significant and variable dilution of the runoff reaching the swale. This result has important implications for evaluating the treatment efficiency of the system.

The assimilation of the nearly water insoluble substrates hydrocarbons and lipids by bacteria entails specific adaptations such as the formation of oleolytic biofilms. The present article reports that the extracellular matrix of an oleolytic biofilm formed by Marinobacter hydrocarbonoclasticus at n-hexadecane-water interfaces is largely composed of proteins typically cytoplasmic such as translation factors and chaperones, and a lesser amount of proteins of unknown function that are predicted extra-cytoplasmic. Matrix proteins appear to form a structured film on hydrophobic interfaces and were found mandatory for the development of biofilms on lipids, alkanes and polystyrene. Exo-proteins secreted through the type-2 secretion system (T2SS) were shown to be essential for the formation of oleolytic biofilms on both alkanes and triglycerides. The T2SS effector involved in biofilm formation on triglycerides was identified as a lipase. In the case of biofilm formation on n-hexadecane, the T2SS effector is likely involved in the mass transfer, capture or transport of alkanes. We propose that M. hydrocarbonoclasticus uses cytoplasmic proteins released by cell lysis to form a proteinaceous matrix and dedicated proteins secreted through the T2SS to act specifically in the assimilation pathways of hydrophobic substrates., (© 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.)

Microevolution associated with emergence and expansion of new epidemic clones of bacterial pathogens holds the key to epidemiologic success. To determine microevolution associated with monophasic Salmonella Typhimurium during an epidemic, we performed comparative whole-genome sequencing and phylogenomic analysis of isolates from the United Kingdom and Italy during 2005-2012. These isolates formed a single clade distinct from recent monophasic epidemic clones previously described from North America and Spain. The UK monophasic epidemic clones showed a novel genomic island encoding resistance to heavy metals and a composite transposon encoding antimicrobial drug resistance genes not present in other Salmonella Typhimurium isolates, which may have contributed to epidemiologic success. A remarkable amount of genotypic variation accumulated during clonal expansion that occurred during the epidemic, including multiple independent acquisitions of a novel prophage carrying the sopE gene and multiple deletion events affecting the phase II flagellin locus. This high level of microevolution may affect antigenicity, pathogenicity, and transmission.

The first record of urban speleothems used to reconstruct the history of heavy metal pollution of shallow groundwaters is presented. Two speleothems grew during the last 300 years in an underground aqueduct in the north-eastern part of Paris. They display high Pb, Mn V, Cu, Cd and Al concentrations since 1900 due to the urbanization of the site which triggered anthropogenic contamination of the water feeding the speleothems. Surprisingly, these heavy metal concentrations are also high in the oldest part. This early pollution could come from the use of Parisian waste as fertilizers in the orchards and vineyards cultivated above the aqueduct before urbanization. Lead isotopes were measured in these carbonates as well as in lead artifacts from the 17th-18th centuries ((206)Pb/(207)Pb=1.180+/-0.003). The mean (206)Pb/(207)Pb ratio, for one of the speleothems is 1.181+/-0.003 unvarying with time. These lead signatures are close to those of coal and old lead from northern European mines, lower than the natural background signature. It confirms that the high metal concentrations found come from anthropogenic pollution. Conversely, the lead isotopic composition of the second speleothem presents two temporal trends: for the oldest levels, the mean value (1.183+/-0.003) is similar to the first speleothem. For the youngest part, a lower value (1.172+/-0.005) is recorded, evidencing the contribution of a new lead source at the beginning of the industrial revolution. Pb isotopes were also measured in recent samples from a nearby superficial site. The first sample is a recent (AD 1975+/-15 years) deposit ((206)Pb/(207)Pb=1.148+/-0.003), and the second, a thin subactual layer ((206)Pb/(207)Pb=1.181+/-0.002). These data are compatible with the adding of anthropogenic sources (leaded gasoline and industrial lead from Rio Tinto ore)., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Laboratory studies have sometimes failed to detect a relationship between toxic stress and morphological defects in invertebrates. Several hypotheses have been proposed to account for this lack of effect. (1) It was suggested that only a combination of stressful conditions - rather than a single one - would affect the phenotype. (2) Phenotypic defects should be detected on adult individuals, rather than on juveniles. (3) Phenotypic abnormalities might mostly affect the progeny of the exposed individuals, some contaminants exhibiting trans-generational effects. In the present study, we test those three hypotheses. We first examined the effects of a multiple exposure by using laboratory Chironomus riparius larvae cultured on two sediments sampled in contaminated rivers and those containing a mixture of mineral and organic compounds. On the larvae, we investigated mentum phenotypes: the frequency of phenodeviants, the shape fluctuating asymmetry and the mean shape. To test whether adult's morphology was more sensitive than the larval's, we also measured asymmetry and mean shape of the adult wings. Finally, to test for a trans-generational phenotypic effect, we measured mentum shape variations in the offspring derived from the measured adults. Overall, our results point out a very limited phenotypic response to contaminated sediments, suggesting that a multiple exposure is not necessarily sufficient to generate phenotypic defects. Adult traits were no more affected than larval traits, discarding the hypothesis that adult phenotypes would be more sensitive biomarkers. Finally, no effect was detected on the offspring generation, suggesting that no trans-generational effect occurs. This general lack of effect suggests that the use of phenotypic defects in C. riparius as an indicator of sediment contamination should be considered cautiously., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Expression of genes of the locus of enterocyte effacement (LEE) is essential for adherence of enterohemorrhagic Escherichia coli (EHEC) to intestinal epithelial cells. Gut factors that may modulate LEE gene expression may therefore influence the outcome of the infection. Because nitric oxide (NO) is a critical effector of the intestinal immune response that may induce transcriptional regulation in enterobacteria, we investigated its influence on LEE expression in EHEC O157:H7. We demonstrate that NO inhibits the expression of genes belonging to LEE1, LEE4, and LEE5 operons, and that the NO sensor nitrite-sensitive repressor (NsrR) is a positive regulator of these operons by interacting directly with the RNA polymerase complex. In the presence of NO, NsrR detaches from the LEE1/4/5 promoter regions and does not activate transcription. In parallel, two regulators of the acid resistance pathway, GadE and GadX, are induced by NO through an indirect NsrR-dependent mechanism. In this context, we show that the NO-dependent LEE1 down-regulation is due to absence of NsrR-mediated activation and to the repressor effect of GadX. Moreover, the inhibition of expression of LEE4 and LEE5 by NO is due to loss of NsrR-mediated activation, to LEE1 down-regulation and to GadE up-regulation. Lastly, we establish that chemical or cellular sources of NO inhibit the adherence of EHEC to human intestinal epithelial cells. These results highlight the critical effect of NsrR in the regulation of the LEE pathogenicity island and the potential role of NO in the limitation of colonization by EHEC.

The aim of the present study was to assess the potential use of biochemical markers and mentum deformities as indicators of long-term exposure to lead (Pb) in Chironomus riparius larvae. To do this, the authors measured 3 biochemical markers (i.e., malondialdehyde level, metallothionein concentration, and energy reserve content) as well as larval growth and mentum deformities after 16-d exposure to sediment containing Pb. The concentrations studied ranged from 3.5 mg/kg to 505.5 mg/kg dry weight. Despite the bioaccumulation of Pb in C. riparius bodies, frequencies of both mentum deformities and the dry weight were not significantly different between the control and stressed groups. On the contrary, Pb exposure caused a significant increase of both malondialdehyde level and metallothionein concentration. The increase of body Pb concentrations did not significantly modify body copper and zinc concentrations. Moreover, we observed a decrease of total lipid content and an increase of glycogen content as a function of a dose-response relationship, while no variation in protein concentrations was observed. Despite the adverse effects observed at the biochemical level, larval development was not affected. These results suggested that measurements of malondialdehyde level, metallothionein concentration, and energy reserve content can be used as relevant biomarkers of long-term sublethal exposure to Pb in C. riparius larvae., (© 2013 SETAC.)

Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a foodborne pathogen that resists the acidic gastric environment, colonizes the gut epithelium, and causes hemorrhagic colitis and hemolytic-uremic syndrome, especially in children. The genomic island OI-47 of E. coli O157:H7 contains a gene, z1528, encoding an EAL-domain protein potentially involved in c-di-GMP hydrolysis that is absent in non-pathogenic E. coli. This gene, designated vmpA, is co-transcribed with ycdT, which is present in non pathogenic E. coli and encodes a diguanylate cyclase involved in c-di-GMP synthesis. To test for vmpA function, we constructed a vmpA knockout mutant. We also overexpressed vmpA, purified the VmpA protein and assayed for its activity in vitro. We found that VmpA possesses c-di-GMP phosphodiesterase activity and that the vmpA mutation results in increased biofilm formation, and reduced swimming motility, which is consistent with the function determined in vitro. Unexpectedly, suppressor mutations arise frequently in the vmpA background suggesting that VmpA plays an important regulatory role in E. coli O157:H7. These findings represent an example of remarkable flexibility in the organization of c-di-GMP signaling pathways in closely related species., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Deformities and fluctuating asymmetry in chironomid larvae have been proposed as sensitive indicators of biological stress and are commonly used to assess the ecological impact of human activities. In particular, they have been associated in Chironomus riparius, the most commonly used species, with heavy metal and pesticide river pollution. In this study, the effect of lead and 4-nonylphenol on mouthpart morphological variation of Chironomus riparius larvae was investigated by traditional and geometric morphometrics. For this purpose, first to fourth instar larvae were exposed to sediment spiked with lead (from 3.0 to 456.9 mg/kg dry weight) or 4-NP (from 0.1 to 198.8 mg/kg dry weight). Mentum phenotypic response to pollutants was assessed by four parameters: (1) the frequency of deformities, (2) fluctuating asymmetry of mentum length, (3) fluctuating asymmetry of mentum shape and (4) the mentum mean shape changes. Despite the bioaccumulation of pollutants in the chironomid's body, no significant differences between control and stressed groups were found for mouthpart deformities and fluctuating asymmetry of mentum length. Slight effects on mentum shape fluctuating asymmetry were observed for two stressed groups. Significant mean shape changes, consisting of tooth size increase and tooth closing, were detected for lead and 4-NP exposure respectively. Those variations, however, were negligible in comparison to mentum shape changes due to genetic effects. These results suggest that the use of mentum variation as an indicator of toxic stress in Chironomus riparius should be considered cautiously.

We previously showed that genomic imprinting regulates matrix attachment region activities at the mouse Igf2 (insulin-like growth factor 2) locus and that these activities are functionally linked to neighboring differentially methylated regions (DMRs). Here, we investigate the similarly structured Dlk1/Gtl2 imprinted domain and show that in the mouse liver, the G/C-rich intergenic germ line-derived DMR, a sequence involved in domain-wide imprinting, is highly retained within the nuclear matrix fraction exclusively on the methylated paternal copy, reflecting its differential function on that chromosome. Therefore, not only "classical" A/T-rich matrix attachment region (MAR) sequences but also other important regulatory DNA elements (such as DMRs) can be recovered from genomic MAR assays following a high salt treatment. Interestingly, the recovery of one A/T-rich sequence (MAR4) from the "nuclear matrix" fraction is strongly correlated with gene expression. We show that this element possesses an intrinsic activity that favors transcription, and using chromosome conformation capture quantitative real time PCR assays, we demonstrate that the MAR4 interacts with the intergenic germ line-derived DMR specifically on the paternal allele but not with the Dlk1/Gtl2 promoters. Altogether, our findings shed a new light on gene regulation at this locus.