Showing papers on "Escherichia coli published in 2020"
TL;DR: Several pairs or groups of the E. coli antigens that have related structures show close relationships of the O antigen gene clusters within clades, thereby highlighting the genetic basis of the evolution of diversity.
Abstract: Escherichia coli includes clonal groups of both commensal and pathogenic strains, with some of the latter causing serious infectious diseases. O antigen variation is current standard in defining strains for taxonomy and epidemiology, providing the basis for many serotyping schemes for Gram-negative bacteria. This review covers the diversity in E. coli O antigen structures and gene clusters, and the genetic basis for the structural diversity. Of the 187 formally defined O antigens, six (O31, O47, O67, O72, O94 and O122) have since been removed and three (O34, O89 and O144) strains do not produce any O antigen. Therefore, structures are presented for 176 of the 181 E. coli O antigens, some of which include subgroups. Most (93%) of these O antigens are synthesized via the Wzx/Wzy pathway, 11 via the ABC transporter pathway, with O20, O57 and O60 still uncharacterized due to failure to find their O antigen gene clusters. Biosynthetic pathways are given for 38 of the 49 sugars found in E. coli O antigens, and several pairs or groups of the E. coli antigens that have related structures show close relationships of the O antigen gene clusters within clades, thereby highlighting the genetic basis of the evolution of diversity.
124 citations
TL;DR: A high-throughput in vitro screening assay to isolate intestinal commensal bacteria with anti-inflammatory capacity from a healthy fecal microbiota transplantation donor found that the Bacteroides strains isolated and characterized have potential to be used as so-called next-generation probiotics.
Abstract: Altered intestinal microbiota is associated with systemic and intestinal diseases, such as inflammatory bowel disease (IBD). Dysbiotic microbiota with enhanced proinflammatory capacity is characterized by depletion of anaerobic commensals, increased proportion of facultatively anaerobic bacteria, as well as reduced diversity and stability. In this study, we developed a high-throughput in vitro screening assay to isolate intestinal commensal bacteria with anti-inflammatory capacity from a healthy fecal microbiota transplantation donor. Freshly isolated gut bacteria were screened for their capacity to attenuate Escherichia coli lipopolysaccharide (LPS)-induced interleukin 8 (IL-8) release from HT-29 cells. The screen yielded a number of Bacteroides and Parabacteroides isolates, which were identified as P. distasonis, B. caccae, B. intestinalis, B. uniformis, B. fragilis, B. vulgatus and B. ovatus using whole genome sequencing. We observed that a cell-cell contact with the epithelium was not necessary to alleviate in vitro inflammation as spent culture media from the isolates were also effective and the anti-inflammatory action did not correlate with the enterocyte adherence capacity of the isolates. The anti-inflammatory isolates also exerted enterocyte monolayer reinforcing action and lacked essential genes to synthetize hexa-acylated, proinflammatory lipid A, part of LPS. Yet, the anti-inflammatory effector molecules remain to be identified. The Bacteroides strains isolated and characterized in this study have potential to be used as so-called next-generation probiotics.
82 citations
TL;DR: GEO could inhibit the expression of some genes linked to bacterial energy metabolism, tricarboxylic acid cycle, cell membrane-related proteins, and DNA metabolism, indicating its suitability in food perseveration.
Abstract: Though essential oils exhibit antibacterial activity against food pathogens, their underlying mechanism is understudied. We extracted ginger essential oil (GEO) using supercritical CO2 and steam distillation. A chemical composition comparison by GC-MS showed that the main components of the extracted GEOs were zingiberene and α-curcumene. Their antibacterial activity and associated mechanism against Staphylococcus aureus and Escherichia coli were investigated. The diameter of inhibition zone (DIZ) of GEO against S. aureus was 17.1 mm, with a minimum inhibition concentration (MIC) of 1.0 mg/mL, and minimum bactericide concentration (MBC) of 2.0 mg/mL. For E. coli, the DIZ was 12.3 mm with MIC and MBC values of 2.0 mg/mL and 4.0 mg/mL, respectively. The SDS-PAGE analysis revealed that some of the electrophoretic bacterial cell proteins bands disappeared with the increase in GEO concentration. Consequently, the nucleic acids content of bacterial suspension was raised significantly and the metabolic activity of bacteria was markedly decreased. GEO could thus inhibit the expression of some genes linked to bacterial energy metabolism, tricarboxylic acid cycle, cell membrane-related proteins, and DNA metabolism. Our findings speculate the bactericidal effects of GEO primarily through disruption of the bacterial cell membrane indicating its suitability in food perseveration.
80 citations
TL;DR: In vitro findings indicate that O. splanchnicus and its effector molecules transported in OMVs could potentially exert anti-inflammatory action in the gut epithelium, and seems to be a commensal with a primarily beneficial interaction with the host.
Abstract: Odoribacter splanchnicus, belonging to the order Bacteroidales, is a common, short-chain fatty acid producing member of the human intestinal microbiota. A decreased abundance of Odoribacter has been linked to different microbiota-associated diseases, such as non-alcoholic fatty liver disease, cystic fibrosis and inflammatory bowel disease (IBD). The type strain of O. splanchnicus has been genome-sequenced, but otherwise very little is known about this anaerobic bacterium. The species surfaces in many microbiota studies and, consequently, comprehension on its interactions with the host is needed. In this study, we isolated a novel strain of O. splanchnicus from a healthy fecal donor, identified it by genome sequencing and addressed its adhesive, epithelium reinforcing and immunoregulatory properties. Our results show that O. splanchnicus strain 57 is non-adherent to enterocytes or mucus, does not reinforce nor compromise Caco-2 monolayer integrity and most likely harbors penta-acylated, less endotoxic lipid A as part of its lipopolysaccharide (LPS) structure based on the lack of gene lpxM and in vitro results on low-level NF-κB activity. The studies by transmission electron microscopy revealed that O. splanchnicus produces outer membrane vesicles (OMV). O. splanchnicus cells, culture supernatant i.e., spent medium or OMVs did not induce interleukin-8 (IL-8) response in HT-29 enterocyte cells suggesting a very low proinflammatory capacity. On the contrary, the treatment of HT-29 cells with O. splanchnicus cells, spent medium or OMVs prior to exposure to Escherichia coli LPS elicited a significant decrease in IL-8 production as compared to E. coli LPS treatment alone. Moreover, O. splanchnicus spent supernatant induced IL-10 production by immune cells, suggesting anti-inflammatory activity. Our in vitro findings indicate that O. splanchnicus and its effector molecules transported in OMVs could potentially exert anti-inflammatory action in the gut epithelium. Taken together, O. splanchnicus seems to be a commensal with a primarily beneficial interaction with the host.
79 citations
TL;DR: Recent findings about reservoirs of STEC are summarized and a better understanding of environmental transmission to humans will facilitate the development of novel strategies for preventing zoonotic STEC infection.
Abstract: Following infection with certain strains of Shiga toxin-producing Escherichia coli (STEC), particularly enterohemorrhagic ones, patients are at elevated risk for developing life-threatening extraintestinal complications, such as acute renal failure. Hence, these bacteria represent a public health concern in both developed and developing countries. Shiga toxins (Stxs) expressed by STEC are highly cytotoxic class II ribosome-inactivating proteins and primary virulence factors responsible for major clinical signs of Stx-mediated pathogenesis, including bloody diarrhea, hemolytic uremic syndrome (HUS), and neurological complications. Ruminant animals are thought to serve as critical environmental reservoirs of Stx-producing Escherichia coli (STEC), but other emerging or arising reservoirs of the toxin-producing bacteria have been overlooked. In particular, a number of new animal species from wildlife and aquaculture industries have recently been identified as unexpected reservoir or spillover hosts of STEC. Here, we summarize recent findings about reservoirs of STEC and review outbreaks of these bacteria both within and outside the United States. A better understanding of environmental transmission to humans will facilitate the development of novel strategies for preventing zoonotic STEC infection.
79 citations
TL;DR: The prevalence of antimicrobial resistance in these commensal bacteria (or others, such as enterococci) can be a good indicator for the selective pressure caused by the use of antimacterial agents, providing an early warning of the emergence of antim antibiotic resistance in pathogens.
Abstract: Escherichia coli are facultative, anaerobic Gram-negative rods with many facets. Within resistant bacterial populations, they play an important ecological role and can be used as a bioindicator of antimicrobial resistance. All animal species used for food production, as well as humans, carry E. coli in their intestinal tracts; plus, the genetic flexibility and adaptability of this bacteria to constantly changing environments allows it to acquire a great number of antimicrobial resistance mechanisms. Thus, the prevalence of antimicrobial resistance in these commensal bacteria (or others, such as enterococci) can be a good indicator for the selective pressure caused by the use of antimicrobial agents, providing an early warning of the emergence of antimicrobial resistance in pathogens. As many as 90% of E. coli strains are commensals inhabiting the intestinal tracts of humans and warm-blooded animals. As a commensal, it lives in a mutually beneficial association with its hosts and rarely causes diseases. However, E. coli also remains as one of the most frequent causes of several common bacterial infections in humans and animals. In humans, it is the prominent cause of enteritis, community- and hospital-acquired urinary tract infection (UTI), septicemia, postsurgical peritonitis, and other clinical infections, such as neonatal meningitis, while, in farm animals, it is more prominently associated with diarrhea. On a global scale, E. coli can be considered the most important human pathogen, causing severe infection along with other major bacterial foodborne agents, such as Salmonella spp. and Campylobacter. Thus, the importance of resistance in E. coli, typically considered a benign commensal, should not be underestimated.
78 citations
TL;DR: An acid-tolerance response system that is important for E. coli survival in the mouse intestine and for production of higher level of 3-hydroxypropionate during fermentation is identified and appears to be conserved in other Gram-negative bacteria.
Abstract: The ability to grow at moderate acidic conditions (pH 4.0–5.0) is important to Escherichia coli colonization of the host’s intestine. Several regulatory systems are known to control acid resistance in E. coli, enabling the bacteria to survive under acidic conditions without growth. Here, we characterize an acid-tolerance response (ATR) system and its regulatory circuit, required for E. coli exponential growth at pH 4.2. A two-component system CpxRA directly senses acidification through protonation of CpxA periplasmic histidine residues, and upregulates the fabA and fabB genes, leading to increased production of unsaturated fatty acids. Changes in lipid composition decrease membrane fluidity, F0F1-ATPase activity, and improve intracellular pH homeostasis. The ATR system is important for E. coli survival in the mouse intestine and for production of higher level of 3-hydroxypropionate during fermentation. Furthermore, this ATR system appears to be conserved in other Gram-negative bacteria. The ability to grow at acidic pH is crucial for E. coli colonization of the host’s intestine. Here, the authors identify an acid-tolerance response system that is important for E. coli exponential growth at pH 4.2, survival in the mouse intestine, and production of 3-hydroxypropionate during fermentation.
72 citations
TL;DR: A review of a subgroup of GIs from E. coli termed pathogenicity islands (PAIs), a concept defined in the late 1980s by Jörg Hacker and colleagues in Werner Goebel’s group at the University of WürZburg, Würzburg, Germany, which is summarized in this review.
Abstract: Escherichia coli is a versatile bacterial species that includes both harmless commensal strains and pathogenic strains found in the gastrointestinal tract in humans and warm-blooded animals. The growing amount of DNA sequence information generated in the era of "genomics" has helped to increase our understanding of the factors and mechanisms involved in the diversification of this bacterial species. The pathogenic side of E. coli that is afforded through horizontal transfers of genes encoding virulence factors enables this bacterium to become a highly diverse and adapted pathogen that is responsible for intestinal or extraintestinal diseases in humans and animals. Many of the accessory genes acquired by horizontal transfers form syntenic blocks and are recognized as genomic islands (GIs). These genomic regions contribute to the rapid evolution, diversification and adaptation of E. coli variants because they are frequently subject to rearrangements, excision and transfer, as well as to further acquisition of additional DNA. Here, we review a subgroup of GIs from E. coli termed pathogenicity islands (PAIs), a concept defined in the late 1980s by Jorg Hacker and colleagues in Werner Goebel's group at the University of Wurzburg, Wurzburg, Germany. As with other GIs, the PAIs comprise large genomic regions that differ from the rest of the genome by their G + C content, by their typical insertion within transfer RNA genes, and by their harboring of direct repeats (at their ends), integrase determinants, or other mobility loci. The hallmark of PAIs is their contribution to the emergence of virulent bacteria and to the development of intestinal and extraintestinal diseases. This review summarizes the current knowledge on the structure and functional features of PAIs, on PAI-encoded E. coli pathogenicity factors and on the role of PAIs in host-pathogen interactions.
71 citations
TL;DR: This is the first report on single phage capable of simultaneously controlling S. Enteritidis, S. Typhimurium and E. coli O157:H7 in both in vitro and in foods.
70 citations
TL;DR: The present work studied the effects of natural sphalerite nanoparticles on the horizontal transfer of ARGs from Escherichia coli DH5α (CTX) to E. coli C600 (Sm) (recipient), and their underlying mechanisms, offering new mechanistic understanding of risks of bacterial resistance resulting from NS.
67 citations
TL;DR: The engineered Escherichia coli strain can grow to an optical density at 600 nm of 7.38 in 450 h, and shows promise as a platform strain growing on CO2 and formic acid alone.
Abstract: We engineered Escherichia coli to grow on CO2 and formic acid alone by introducing the synthetic CO2 and formic acid assimilation pathway, expressing two formate dehydrogenase genes, fine-tuning metabolic fluxes and optimizing the levels of cytochrome bo3 and bd-I ubiquinol oxidase. Our engineered strain can grow to an optical density at 600 nm of 7.38 in 450 h, and shows promise as a platform strain growing on CO2 and formic acid alone. Growth of Escherichia coli on carbon dioxide and formate is achieved by rational metabolic engineering alone.
TL;DR: This work provides tools for the facile discovery and development of high-accumulating compounds in E. coli, and a general blueprint for the conversion of Gram-positive-only compounds into broad-spectrum antibiotics.
Abstract: Gram-negative bacterial infections are a significant public health concern, and the lack of new drug classes for these pathogens is linked to the inability of most drug leads to accumulate inside Gram-negative bacteria1-7. Here, we report the development of a web application-eNTRyway-that predicts compound accumulation (in Escherichia coli) from its structure. In conjunction with structure-activity relationships and X-ray data, eNTRyway was utilized to re-design Debio-1452-a Gram-positive-only antibiotic8-into versions that accumulate in E. coli and possess antibacterial activity against high-priority Gram-negative pathogens. The lead compound Debio-1452-NH3 operates as an antibiotic via the same mechanism as Debio-1452, namely potent inhibition of the enoyl-acyl carrier protein reductase FabI, as validated by in vitro enzyme assays and the generation of bacterial isolates with spontaneous target mutations. Debio-1452-NH3 is well tolerated in vivo, reduces bacterial burden in mice and rescues mice from lethal infections with clinical isolates of Acinetobacter baumannii, Klebsiella pneumoniae and E. coli. This work provides tools for the facile discovery and development of high-accumulating compounds in E. coli, and a general blueprint for the conversion of Gram-positive-only compounds into broad-spectrum antibiotics.
TL;DR: In vitro and in vivo inactivation kinetics, morphological changes, and protein leakage showed higher acid tolerance of E. coli O26:H11, and real-time PCR tests confirmed that glutamic acid dependent decarboxylase/antiporter system was the major acid resistance mechanism.
TL;DR: An overview of hybrid- and hetero-pathogenic E. coli pathotypes is provided and it is clear that genes encoding some virulence factors, such as Shiga toxin, are found among different E. bacteria pathotypes to which they have not traditionally been associated, perhaps foreshowing their emergence in new and severe outbreaks caused by such hybrid strains.
Abstract: Although extraintestinal pathogenic Escherichia coli (ExPEC) are designated by their isolation site and grouped based on the type of host and the disease they cause, most diarrheagenic E coli (DEC) are subdivided into several pathotypes based on the presence of specific virulence traits directly related to disease development This scenario of a well-categorized E coli collapsed after the German outbreak of 2011, caused by one strain bearing the virulence factors of two different DEC pathotypes (enteroaggregative E coli and Shiga toxin-producing E coli) Since the outbreak, many studies have shown that this phenomenon is more frequent than previously realized Therefore, the terms hybrid- and hetero-pathogenic E coli have been coined to describe new combinations of virulence factors among the classic E coli pathotypes In this review, we provide an overview of these classifications and highlight the E coli genomic plasticity that results in some mixed E coli pathotypes displaying novel pathogenic strategies, which lead to a new symptomatology related to E coli diseases In addition, as the capacity for genome interrogation has grown in the last few years, it is clear that genes encoding some virulence factors, such as Shiga toxin, are found among different E coli pathotypes to which they have not traditionally been associated, perhaps foreshowing their emergence in new and severe outbreaks caused by such hybrid strains Therefore, further studies regarding hetero-pathogenic and hybrid-pathogenic E coli isolates are necessary to better understand and control the spread of these pathogens
TL;DR: It is shown that the gut is detectably colonized within 16 h of birth, with Escherichia coli dominating, and that this correlates with proteome and metabolome changes including the fermentation of amino acids, which provides a mechanism for the initial growth of E. coli under anaerobic conditions.
Abstract: Initial microbial colonization and later succession in the gut of human infants are linked to health and disease later in life. The timing of the appearance of the first gut microbiome, and the consequences for the early life metabolome, are just starting to be defined. Here, we evaluated the gut microbiome, proteome and metabolome in 88 African-American newborns using faecal samples collected in the first few days of life. Gut bacteria became detectable using molecular methods by 16 h after birth. Detailed analysis of the three most common species, Escherichia coli, Enterococcus faecalis and Bacteroides vulgatus, did not suggest a genomic signature for neonatal gut colonization. The appearance of bacteria was associated with reduced abundance of approximately 50 human proteins, decreased levels of free amino acids and an increase in products of bacterial fermentation, including acetate and succinate. Using flux balance modelling and in vitro experiments, we provide evidence that fermentation of amino acids provides a mechanism for the initial growth of E. coli, the most common early colonizer, under anaerobic conditions. These results provide a deep characterization of the first microbes in the human gut and show how the biochemical environment is altered by their appearance. Using a multi-omics approach to analyse meconium and stool samples from babies during the first few days of life, the authors show that the gut is detectably colonized within 16 h of birth, with Escherichia coli dominating, and that this correlates with proteome and metabolome changes including the fermentation of amino acids.
TL;DR: The identification of a novel Stx2 subtype, designated Stx1/Stx2k, in E. coli strains widely detected from diarrheal patients, animals, and raw meats in China over time is reported and highlights the extraordinary genomic plasticity of STEC strains.
TL;DR: It is shown that the machinery is needed to promote the cleavage of cell wall glycans at the division site to promote daughter cell separation in E. coli tol-pal mutants, indicating that the Tol-Pal system may play a more general role in coordinating OM invagination with PG remodeling at thedivision site than previously appreciated.
Abstract: Tol-Pal is a multiprotein system present in the envelope of Gram-negative bacteria. Inactivation of this widely conserved machinery compromises the outer membrane (OM) layer of these organisms, resulting in hypersensitivity to many antibiotics. Mutants in the tol-pal locus fail to complete division and form cell chains. This phenotype along with the localization of Tol-Pal components to the cytokinetic ring in Escherichia coli has led to the proposal that the primary function of the system is to promote OM constriction during division. Accordingly, a poorly constricted OM is believed to link the cell chains formed upon Tol-Pal inactivation. However, we show here that cell chains of E. coli tol-pal mutants are connected by an incompletely processed peptidoglycan (PG) layer. Genetic suppressors of this defect were isolated and found to overproduce OM lipoproteins capable of cleaving the glycan strands of PG. Among the factors promoting cell separation in mutant cells was a protein of previously unknown function (YddW), which we have identified as a divisome-localized glycosyl hydrolase that cleaves peptide-free PG glycans. Overall, our results indicate that the cell chaining defect of Tol-Pal mutants cannot simply be interpreted as a defect in OM constriction. Rather, the complex also appears to be required for the activity of several OM-localized enzymes with cell wall remodeling activity. Thus, the Tol-Pal system may play a more general role in coordinating OM invagination with PG remodeling at the division site than previously appreciated.
TL;DR: It is shown that bacteriophage can be used as a vector for delivery of plasmid DNA to bacteria colonizing the gastrointestinal tract, using filamentous phage M13 and Escherichia coli engrafted in the gut microbiota of mice, and suggested that M13-delivered CRISPR-Cas9 may be better suited for targeted genomic deletions in vivo that harness the robust DNA repair response of bacteria.
Abstract: The recognition that the gut microbiome has a profound influence on human health and disease has spurred efforts to manipulate gut microbial community structure and function. Though various strategies for microbiome engineering have been proposed, methods for phage-based genetic manipulation of resident members of the gut microbiota in vivo are currently lacking. Here, we show that bacteriophage can be used as a vector for delivery of plasmid DNA to bacteria colonizing the gastrointestinal tract, using filamentous phage M13 and Escherichia coli engrafted in the gut microbiota of mice. We employ M13 to deliver CRISPR-Cas9 for sequence-specific targeting of E. coli leading to depletion of one strain of a pair of fluorescently marked isogenic strains competitively colonizing the gut. We further show that when mice are colonized by a single E. coli strain, it is possible for M13-delivered CRISPR-Cas9 to induce genomic deletions that encompass the targeted gene. Our results suggest that rather than being developed for use as an antimicrobial in the gut microbiome, M13-delivered CRISPR-Cas9 may be better suited for targeted genomic deletions in vivo that harness the robust DNA repair response of bacteria. With improved methods to mitigate undesired escape mutations, we envision these strategies may be developed for targeted removal of strains or genes present in the gut microbiome that are detrimental to the host. These results provide a highly adaptable platform for in vivo microbiome engineering using phage and a proof-of-concept for the establishment of phage-based tools for a broader panel of human gut bacteria.
TL;DR: New Ni2+-doped zinc oxide (Ni-ZnO or NZO) nanostructures are synthesized as targeted antibacterial agents for Gram-negative bacteria and show excellent antibacterial activity against MDR strains of A. baumannii and E. coli.
Abstract: Infections by multidrug-resistant (MDR) bacteria are one of the most threatening concerns for public health. For this purpose, nanomaterials have emerged with great potential for antibacterial activity. In this paper, we report the synthesis of new Ni2+-doped zinc oxide (Ni-ZnO or NZO) nanostructures as targeted antibacterial agents for Gram-negative bacteria. A one-pot low-temperature solution process was used with varying compositions containing 2 or 5% Ni2+ relative to Zn2+, resulting in 2NZO or 5NZO, respectively. X-ray diffractometry, transmission electron microscopy, and X-ray photoelectron spectroscopy were used for material characterization. Further, the antibacterial activity against both Gram-negative [Escherichia coli (E. coli) and Acinetobacter baumannii (A. baumannii) strains including standard, MDR, and clinical isolates associated with mcr-1 gene] and Gram-positive (Staphylococcus aureus and Staphylococcus epidermidis) bacteria were evaluated through analysis of zone of inhibition, minimum inhibitory concentration (MIC), and scanning electron microscopy images. Among the prepared nanostructures, the 5NZO sample showed excellent antibacterial activity against MDR strains of A. baumannii and E. coli. In addition, samples of NZO generated approximately 7 to 16 times more reactive oxygen species (ROS) in E. coli compared to ZnO. Our synthesized nanomaterials have the potential to fight MDR and colistin-resistant Gram-negative bacteria.
TL;DR: Results provided further evidence of the metabolomic and transcriptomic response of E. coli O157:H7 to oxidation and heat stress and demonstrated that treatment with EW and heat caused significant perturbation of metabolic pathways that were functionally related with amino acid metabolism, nucleotides synthesis, and lipid biosynthesis.
TL;DR: In conclusion, pks+ E. coli was more often isolated from tissue of CRC patients compared to healthy individuals, and in-vitro assays suggest these isolated strains may be involved in the initiation and development of CRC.
Abstract: Escherichia coli (E. coli) from the B2 phylogenetic group is implicated in colorectal cancer (CRC) as it possesses a genomic island, termed polyketide synthetase (pks), which codes for the synthesis of colibactin, a genotoxin that induces DNA damage, cell cycle arrest, mutations and chromosomal instability in eukaryotic cells. The aim of this study was to detect and compare the prevalence of E. coli expressing pks (pks+ E. coli) in CRC patients and healthy controls followed by investigating the virulence triggered by pks+ E. coli using an in-vitro model. Mucosal colon tissues were collected and processed to determine the presence of pks+ E. coli. Thereafter, primary colon epithelial (PCE) and colorectal carcinoma (HCT116) cell lines were used to detect cytopathic response to the isolated pks+ E. coli strains. Our results showed 16.7% and 4.3% of CRC and healthy controls, respectively were pks+ E. coli. Further, PCE displayed syncytia and cell swelling and HCT116 cells, megalocytosis, in response to treatment with the isolated pks+ E. coli strains. In conclusion, pks+ E. coli was more often isolated from tissue of CRC patients compared to healthy individuals, and our in-vitro assays suggest these isolated strains may be involved in the initiation and development of CRC.
TL;DR: Test the hypothesis that Escherichia coli evolution in the mouse gut is more predictable across hosts in the absence of interspecies competition than in the presence of other microbial species, and highlights the metabolic plasticity and evolutionary versatility of E. coli, tailored to the specific ecology it experiences in the gut.
TL;DR: A strain of Escherichia coli was designed to express e-PNs by introducing a plasmid that contained an inducible operon with E. coli genes for type IV pili biogenesis machinery and a synthetic gene designed to yield a peptide monomer that could be assembled into e-PTs.
Abstract: Geobacter sulfurreducens' pilin-based electrically conductive protein nanowires (e-PNs) are a revolutionary electronic material. They offer novel options for electronic sensing applications and have the remarkable ability to harvest electrical energy from atmospheric humidity. However, technical constraints limit mass cultivation and genetic manipulation of G. sulfurreducens. Therefore, we designed a strain of Escherichia coli to express e-PNs by introducing a plasmid that contained an inducible operon with E. coli genes for type IV pili biogenesis machinery and a synthetic gene designed to yield a peptide monomer that could be assembled into e-PNs. The e-PNs expressed in E. coli and harvested with a simple filtration method had the same diameter (3 nm) and conductance as e-PNs expressed in G. sulfurreducens. These results, coupled with the robustness of E. coli for mass cultivation and the extensive E. coli toolbox for genetic manipulation, greatly expand the opportunities for large-scale fabrication of novel e-PNs.
TL;DR: This article revisited the details of these E. coli classic and hybrid pathogens, the increase in antimicrobial resistance in the context of a genetically empowered multifaceted and versatile bug and the growing need to advance alternative therapies to fight these infections.
Abstract: Genetic plasticity promotes evolution and a vast diversity in Escherichia coli varying from avirulent to highly pathogenic strains, including the emergence of virulent hybrid microorganism. This ability also contributes to the emergence of antimicrobial resistance. These hybrid pathogenic E. coli (HyPEC) are emergent threats, such as O104:H4 from the European outbreak in 2011, aggregative adherent bacteria with the potent Shiga-toxin. Here, we briefly revisited the details of these E. coli classic and hybrid pathogens, the increase in antimicrobial resistance in the context of a genetically empowered multifaceted and versatile bug and the growing need to advance alternative therapies to fight these infections.
TL;DR: This study uncovers important regulatory functions of rG4s in bacterial pathogenicity and metabolic pathways and strongly suggests that rG 4s exist and can be detected in a wide range of bacterial species.
Abstract: Guanine (G)-rich sequences in RNA can fold into diverse RNA G-quadruplex (rG4) structures to mediate various biological functions and cellular processes in eukaryotic organisms. However, the presence, locations, and functions of rG4s in prokaryotes are still elusive. We used QUMA-1, an rG4-specific fluorescent probe, to detect rG4 structures in a wide range of bacterial species both in vitro and in live cells and found rG4 to be an abundant RNA secondary structure across those species. Subsequently, to identify bacterial rG4 sites in the transcriptome, the model Escherichia coli strain and a major human pathogen, Pseudomonas aeruginosa, were subjected to recently developed high-throughput rG4 structure sequencing (rG4-seq). In total, 168 and 161 in vitro rG4 sites were found in E. coli and P. aeruginosa, respectively. Genes carrying these rG4 sites were found to be involved in virulence, gene regulation, cell envelope synthesis, and metabolism. More importantly, biophysical assays revealed the formation of a group of rG4 sites in mRNAs (such as hemL and bswR), and they were functionally validated in cells by genetic (point mutation and lux reporter assays) and phenotypic experiments, providing substantial evidence for the formation and function of rG4s in bacteria. Overall, our study uncovers important regulatory functions of rG4s in bacterial pathogenicity and metabolic pathways and strongly suggests that rG4s exist and can be detected in a wide range of bacterial species.IMPORTANCE G-quadruplex in RNA (rG4) mediates various biological functions and cellular processes in eukaryotic organisms. However, the presence, locations, and functions of rG4 are still elusive in prokaryotes. Here, we found that rG4 is an abundant RNA secondary structure across a wide range of bacterial species. Subsequently, the transcriptome-wide rG4 structure sequencing (rG4-seq) revealed that the model E. coli strain and a major human pathogen, P. aeruginosa, have 168 and 161 in vitro rG4 sites, respectively, involved in virulence, gene regulation, cell envelope, and metabolism. We further verified the regulatory functions of two rG4 sites in bacteria (hemL and bswR). Overall, this finding strongly suggests that rG4s play key regulatory roles in a wide range of bacterial species.
TL;DR: It is shown that TspA has membrane-depolarizing activity and that S. aureus uses TSpA to inhibit the growth of a bacterial competitor in vivo, and that deletion of tspA leads to increased bacterial clearance.
Abstract: The type VII protein secretion system (T7SS) is conserved across Staphylococcus aureus strains and plays important roles in virulence and interbacterial competition. To date, only one T7SS substrate protein, encoded in a subset of S. aureus genomes, has been functionally characterized. Here, using an unbiased proteomic approach, we identify TspA as a further T7SS substrate. TspA is encoded distantly from the T7SS gene cluster and is found across all S. aureus strains as well as in Listeria and Enterococci. Heterologous expression of TspA from S. aureus strain RN6390 indicates its C-terminal domain is toxic when targeted to the Escherichia coli periplasm and that it depolarizes the cytoplasmic membrane. The membrane-depolarizing activity is alleviated by coproduction of the membrane-bound TsaI immunity protein, which is encoded adjacent to tspA on the S. aureus chromosome. Using a zebrafish hindbrain ventricle infection model, we demonstrate that the T7SS of strain RN6390 promotes bacterial replication in vivo, and deletion of tspA leads to increased bacterial clearance. The toxin domain of TspA is highly polymorphic and S. aureus strains encode multiple tsaI homologs at the tspA locus, suggestive of additional roles in intraspecies competition. In agreement, we demonstrate TspA-dependent growth inhibition of RN6390 by strain COL in the zebrafish infection model that is alleviated by the presence of TsaI homologs.
TL;DR: Interestingly, differential flagellin regulation was observed between commensal E. coli (HS) and AIEC (LF82) strains:Flagellum expression by AIEC bacteria, in contrast to that of commensals E.E. coli, is enhanced under intestinal conditions (the presence of bile acids and mucins).
Abstract: The pathogenesis of Crohn's disease (CD) is multifactorial and involves genetic susceptibility, environmental triggers and intestinal microbiota. Adherent-invasive Escherichia coli (AIEC) are flagellated bacteria more prevalent in CD patients than in healthy subjects and promote chronic intestinal inflammation. We aim at deciphering the role of flagella and flagellin modulation by intestinal conditions. AIEC flagellum expression is required for optimal adhesion to and invasion of intestinal epithelial cells. Interestingly, differential flagellin regulation was observed between commensal E. coli (HS) and AIEC (LF82) strains: flagellum expression by AIEC bacteria, in contrast to that of commensal E. coli, is enhanced under intestinal conditions (the presence of bile acids and mucins). Flagella are involved in the ability of the AIEC LF82 strain to cross a mucus layer in vitro and in vivo, conferring a selective advantage in penetrating the mucus layer and reaching the epithelial surface. In a CEABAC10 mouse model, a non-motile mutant (LF82-ΔfliC) exhibits reduced colonization that is restored by a dextran sodium sulfate treatment that alters mucus layer integrity. Moreover, a mutant that continuously secretes flagellin (LF82-ΔflgM) triggers a stronger inflammatory response than the wild-type strain, and the mutant's ability to colonize the CEABAC10 mouse model is decreased. Overexpression of flagellin in bacteria in contact with epithelial cells can be detrimental to their virulence by inducing acute inflammation that enhances AIEC clearance. AIEC pathobionts must finely modulate flagellum expression during the infection process, taking advantage of their specific virulence gene regulation to improve their adaptability and flexibility within the gut environment.
12 Feb 2020
TL;DR: The insect antimicrobial peptide cecropin A (CecA) can destroy planktonic and sessile biofilm-forming UPEC cells, either alone or when combined with the antibiotic nalidixic acid (NAL), synergistically clearing infection in vivo without off-target cytotoxicity.
Abstract: Current antibiotics cannot eradicate uropathogenic Escherichia coli (UPEC) biofilms, leading to recurrent urinary tract infections. Here, we show that the insect antimicrobial peptide cecropin A (CecA) can destroy planktonic and sessile biofilm-forming UPEC cells, either alone or when combined with the antibiotic nalidixic acid (NAL), synergistically clearing infection in vivo without off-target cytotoxicity. The multi-target mechanism of action involves outer membrane permeabilization followed by biofilm disruption triggered by the inhibition of efflux pump activity and interactions with extracellular and intracellular nucleic acids. These diverse targets ensure that resistance to the CecA + NAL combination emerges slowly. The antimicrobial mechanisms of CecA, thus, extend beyond pore-forming activity to include an unanticipated biofilm-eradication process, offering an alternative approach to combat antibiotic-resistant UPEC infections.
25 Nov 2020
TL;DR: In this article, a C-2C analog-to digital and digital-to-analog converter is described, the C2C designation referring to the arrangement of capacitance in a capacitor ladder network.
Abstract: A C-2C analog-to digital and digital-to-analog converter is described, the C-2C designation referring to the arrangement of capacitance in a capacitor ladder network. The capacitors are formed in a monolithic, multilayer structure which includes a substrate, diffusion regions in the substrate, a polysilicon layer and an aluminum layer wherein the capacitances are formed between the aluminum layer and the polysilicon layer and between the polysilicon layer and the diffusion region, and these capacitances have the ratio of 2C to C respectively. The capacitor ladder network formed in the multilayer structure can be trimmed or adjusted electrically after manufacture to obtain the desired tolerances.
TL;DR: The object of this review is to improve the understanding of polyphenol interactions with the Gut microbiota and highlights their potential role in modulation of the gut microbiota of chicken.
Abstract: The gastrointestinal tract of the chicken harbors very complex and diverse microbial communities including both beneficial and harmful bacteria. However, a dynamic balance is generally maintained in such a way that beneficial bacteria predominate over harmful ones. Environmental factors can negatively affect this balance, resulting in harmful effects on the gut, declining health, and productivity. This means modulating changes in the chicken gut microbiota is an effective strategy to improve gut health and productivity. One strategy is using modified diets to favor the growth of beneficial bacteria and a key candidate are polyphenols, which have strong antioxidant potential and established health benefits. The gut microbiota-polyphenol interactions are of vital importance in their effects on the gut microbiota modulation because it affects not only the composition of gut bacteria but also improves bioavailability of polyphenols through generation of more bioactive metabolites enhancing their health effects on morphology and composition of the gut microbiota. The object of this review is to improve the understanding of polyphenol interactions with the gut microbiota and highlights their potential role in modulation of the gut microbiota of chicken.