scholarly journals Development of a Continuous Bioconversion System Using a Thermophilic Whole-Cell Biocatalyst

2013 ◽  
Vol 79 (6) ◽  
pp. 1996-2001 ◽  
Author(s):  
Pham Huynh Ninh ◽  
Kohsuke Honda ◽  
Yukako Yokohigashi ◽  
Kenji Okano ◽  
Takeshi Omasa ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Membrane Filter ◽  
Host Cells ◽  
Continuous Reactor ◽  
Side Reactions ◽  
Electron Microscopic ◽  
Whole Cell ◽  
Content Type ◽  
Thermophilic Enzymes ◽  
E Coli

ABSTRACTThe heat treatment of recombinant mesophilic cells having heterologous thermophilic enzymes results in the denaturation of indigenous mesophilic enzymes and the elimination of undesired side reactions; therefore, highly selective whole-cell catalysts comparable to purified enzymes can be readily prepared. However, the thermolysis of host cells leads to the heat-induced leakage of thermophilic enzymes, which are produced as soluble proteins, limiting the exploitation of their excellent stability in repeated and continuous reactions. In this study,Escherichia colicells having the thermophilic fumarase fromThermus thermophilus(TtFTA) were treated with glutaraldehyde to prevent the heat-induced leakage of the enzyme, and the resulting cells were used as a whole-cell catalyst in repeated and continuous reactions. Interestingly, although electron microscopic observations revealed that the cellular structure of glutaraldehyde-treatedE. coliwas not apparently changed by the heat treatment, the membrane permeability of the heated cells to relatively small molecules (up to at least 3 kDa) was significantly improved. By applying the glutaraldehyde-treatedE. colihavingTtFTA to a continuous reactor equipped with a cell-separation membrane filter, the enzymatic hydration of fumarate to malate could be operated for more than 600 min with a molar conversion yield of 60% or higher.

scholarly journals The Repeat-In-Toxin Family Member TosA Mediates Adherence of Uropathogenic Escherichia coli and Survival during Bacteremia

2011 ◽  
Vol 80 (2) ◽  
pp. 493-505 ◽  
Author(s):  
Patrick D. Vigil ◽  
Travis J. Wiles ◽  
Michael D. Engstrom ◽  
Lev Prasov ◽  
Matthew A. Mulvey ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract ◽  
Virulence Factors ◽  
Upper Urinary Tract ◽  
Host Cells ◽  
Content Type ◽  
E Coli ◽  
Wide Range ◽  
Novel Target ◽  
Tract Infections

ABSTRACTUropathogenicEscherichia coli(UPEC) is responsible for the majority of uncomplicated urinary tract infections (UTI) and represents the most common bacterial infection in adults. UPEC utilizes a wide range of virulence factors to colonize the host, including the novel repeat-in-toxin (RTX) protein TosA, which is specifically expressed in the host urinary tract and contributes significantly to the virulence and survival of UPEC.tosA, found in strains within the B2 phylogenetic subgroup ofE. coli, serves as a marker for strains that also contain a large number of well-characterized UPEC virulence factors. The presence oftosAin anE. coliisolate predicts successful colonization of the murine model of ascending UTI, regardless of the source of the isolate. Here, a detailed analysis of the function oftosArevealed that this gene is transcriptionally linked to genes encoding a conserved type 1 secretion system similar to other RTX family members. TosA localized to the cell surface and was found to mediate (i) adherence to host cells derived from the upper urinary tract and (ii) survival in disseminated infections and (iii) to enhance lethality during sepsis (as assessed in two different animal models of infection). An experimental vaccine, using purified TosA, protected vaccinated animals against urosepsis. From this work, it was concluded that TosA belongs to a novel group of RTX proteins that mediate adherence and host damage during UTI and urosepsis and could be a novel target for the development of therapeutics to treat ascending UTIs.

scholarly journals Cooperative Immune Suppression by Escherichia coli and Shigella Effector Proteins

2018 ◽  
Vol 86 (4) ◽  
Author(s):  
Maarten F. de Jong ◽  
Neal M. Alto
Keyword(s):  
Escherichia Coli ◽  
Defense Mechanisms ◽  
Immune Defense ◽  
Effector Proteins ◽  
Innate Immune ◽  
Host Cells ◽  
Secretion Systems ◽  
Content Type ◽  
E Coli ◽  
Type Iii Secretion Systems

ABSTRACT The enteric attaching and effacing (A/E) pathogens enterohemorrhagic Escherichia coli (EHEC) and enteropathogenic E. coli (EPEC) and the invasive pathogens enteroinvasive E. coli (EIEC) and Shigella encode type III secretion systems (T3SS) used to inject effector proteins into human host cells during infection. Among these are a group of effectors required for NF-κB-mediated host immune evasion. Recent studies have identified several effector proteins from A/E pathogens and EIEC/ Shigella that are involved in suppression of NF-κB and have uncovered their cellular and molecular functions. A novel mechanism among these effectors from both groups of pathogens is to coordinate effector function during infection. This cooperativity among effector proteins explains how bacterial pathogens are able to effectively suppress innate immune defense mechanisms in response to diverse classes of immune receptor signaling complexes (RSCs) stimulated during infection.

scholarly journals The Complete Genome of the Atypical Enteropathogenic Escherichia coli Archetype Isolate E110019 Highlights a Role for Plasmids in Dissemination of the Type III Secreted Effector EspT

2019 ◽  
Vol 87 (10) ◽  
Author(s):  
Tracy H. Hazen ◽  
David A. Rasko
Keyword(s):  
Escherichia Coli ◽  
Complete Genome ◽  
Genomic Analysis ◽  
Host Cells ◽  
Comparative Genomic ◽  
Content Type ◽  
E Coli ◽  
Type Iii ◽  
Severe Diarrhea ◽  
Typical Epec

ABSTRACT Enteropathogenic Escherichia coli (EPEC) is a leading cause of moderate to severe diarrhea among young children in developing countries, and EPEC isolates can be subdivided into two groups. Typical EPEC (tEPEC) bacteria are characterized by the presence of both the locus of enterocyte effacement (LEE) and the plasmid-encoded bundle-forming pilus (BFP), which are involved in adherence and translocation of type III effectors into the host cells. Atypical EPEC (aEPEC) bacteria also contain the LEE but lack the BFP. In the current report, we describe the complete genome of outbreak-associated aEPEC isolate E110019, which carries four plasmids. Comparative genomic analysis demonstrated that the type III secreted effector EspT gene, an autotransporter gene, a hemolysin gene, and putative fimbrial genes are all carried on plasmids. Further investigation of 65 espT-containing E. coli genomes demonstrated that different espT alleles are associated with multiple plasmids that differ in their overall gene content from the E110019 espT-containing plasmid. EspT has been previously described with respect to its role in the ability of E110019 to invade host cells. While other type III secreted effectors of E. coli have been identified on insertion elements and prophages of the chromosome, we demonstrated in the current study that the espT gene is located on multiple unique plasmids. These findings highlight a role of plasmids in dissemination of a unique E. coli type III secreted effector that is involved in host invasion and severe diarrheal illness.

scholarly journals Variations in O-Antigen Biosynthesis and O-Acetylation Associated with Altered Phage Sensitivity in Escherichia coli 4s

2014 ◽  
Vol 197 (5) ◽  
pp. 905-912 ◽  
Author(s):  
Yuriy A. Knirel ◽  
Nikolai S. Prokhorov ◽  
Alexander S. Shashkov ◽  
Olga G. Ovchinnikova ◽  
Evelina L. Zdorovenko ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Host Cells ◽  
Side Chain ◽  
Gram Negative Bacteria ◽  
Gene Encoding ◽  
Content Type ◽  
Surface Receptors ◽  
E Coli ◽  
O Antigen ◽  
Phage Sensitivity

The O polysaccharide of the lipopolysaccharide (O antigen) of Gram-negative bacteria often serves as a receptor for bacteriophages that can make the phage dependent on a given O-antigen type, thus supporting the concept of the adaptive significance of the O-antigen variability in bacteria. The O-antigen layer also modulates interactions of many bacteriophages with their hosts, limiting the access of the viruses to other cell surface receptors. Here we report variations of O-antigen synthesis and structure in an environmentalEscherichia coliisolate, 4s, obtained from horse feces, and its mutants selected for resistance to bacteriophage G7C, isolated from the same fecal sample. The 4s O antigen was found to be serologically, structurally, and genetically related to the O antigen ofE. coliO22, differing only in side-chain α-d-glucosylation in the former, mediated by agtrlocus on the chromosome. Spontaneous mutations ofE. coli4s occurring with an unusually high frequency affected either O-antigen synthesis or O-acetylation due to the inactivation of the gene encoding the putative glycosyltransferase WclH or the putative acetyltransferase WclK, respectively, by the insertion of IS1-like elements. These mutations induced resistance to bacteriophage G7C and also modified interactions ofE. coli4s with several other bacteriophages conferring either resistance or sensitivity to the host. These findings suggest that O-antigen synthesis and O-acetylation can both ensure the specific recognition of the O-antigen receptor following infection by some phages and provide protection of the host cells against attack by other phages.

scholarly journals Role of F1C Fimbriae, Flagella, and Secreted Bacterial Components in the Inhibitory Effect of Probiotic Escherichia coli Nissle 1917 on Atypical Enteropathogenic E. coli Infection

2014 ◽  
Vol 82 (5) ◽  
pp. 1801-1812 ◽  
Author(s):  
Sylvia Kleta ◽  
Marcel Nordhoff ◽  
Karsten Tedin ◽  
Lothar H. Wieler ◽  
Rafal Kolenda ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Molecular Mechanisms ◽  
Inhibitory Effect ◽  
Host Cells ◽  
Single Infection ◽  
Content Type ◽  
E Coli ◽  
Initial Adhesion

ABSTRACTEnteropathogenicEscherichia coli(EPEC) is recognized as an important intestinal pathogen that frequently causes acute and persistent diarrhea in humans and animals. The use of probiotic bacteria to prevent diarrhea is gaining increasing interest. The probioticE. colistrain Nissle 1917 (EcN) is known to be effective in the treatment of several gastrointestinal disorders. While bothin vitroandin vivostudies have described strong inhibitory effects of EcN on enteropathogenic bacteria, including pathogenicE. coli, the underlying molecular mechanisms remain largely unknown. In this study, we examined the inhibitory effect of EcN on infections of porcine intestinal epithelial cells with atypical enteropathogenicE. coli(aEPEC) with respect to single infection steps, including adhesion, microcolony formation, and the attaching and effacing phenotype. We show that EcN drastically reduced the infection efficiencies of aEPEC by inhibiting bacterial adhesion and growth of microcolonies, but not the attaching and effacing of adherent bacteria. The inhibitory effect correlated with EcN adhesion capacities and was predominantly mediated by F1C fimbriae, but also by H1 flagella, which served as bridges between EcN cells. Furthermore, EcN seemed to interfere with the initial adhesion of aEPEC to host cells by secretion of inhibitory components. These components do not appear to be specific to EcN, but we propose that the strong adhesion capacities enable EcN to secrete sufficient local concentrations of the inhibitory factors. The results of this study are consistent with a mode of action whereby EcN inhibits secretion of virulence-associated proteins of EPEC, but not their expression.

scholarly journals Hypoxia-Mediated Impairment of the Mitochondrial Respiratory Chain Inhibits the Bactericidal Activity of Macrophages

2012 ◽  
Vol 80 (4) ◽  
pp. 1455-1466 ◽  
Author(s):  
Melanie Wiese ◽  
Roman G. Gerlach ◽  
Isabel Popp ◽  
Jasmin Matuszak ◽  
Mousumi Mahapatro ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Respiratory Chain ◽  
Bactericidal Activity ◽  
Mitochondrial Respiratory Chain ◽  
Host Cells ◽  
Mitochondrial Activity ◽  
Oxygen Intermediates ◽  
Content Type ◽  
E Coli ◽  
Mitochondrial Respiratory

ABSTRACTIn infected tissues oxygen tensions are low. As innate immune cells have to operate under these conditions, we analyzed the ability of macrophages (Mϕ) to killEscherichia coliorStaphylococcus aureusin a hypoxic microenvironment. Oxygen restriction did not promote intracellular bacterial growth but did impair the bactericidal activity of the host cells against both pathogens. This correlated with a decreased production of reactive oxygen intermediates (ROI) and reactive nitrogen intermediates. Experiments with phagocyte NADPH oxidase (PHOX) and inducible NO synthase (NOS2) double-deficient Mϕ revealed that inE. coli- orS. aureus-infected cells the reduced antibacterial activity during hypoxia was either entirely or partially independent of the diminished PHOX and NOS2 activity. Hypoxia impaired the mitochondrial activity of infected Mϕ. Inhibition of the mitochondrial respiratory chain activity during normoxia (using rotenone or antimycin A) completely or partially mimicked the defective antibacterial activity observed in hypoxicE. coli- orS. aureus-infected wild-type Mϕ, respectively. Accordingly, inhibition of the respiratory chain ofS. aureus-infected, normoxic PHOX−/−NOS2−/−Mϕ further raised the bacterial burden of the cells, which reached the level measured in hypoxic PHOX−/−NOS2−/−Mϕ cultures. Our data demonstrate that the reduced killing ofS. aureusorE. coliduring hypoxia is not simply due to a lack of PHOX and NOS2 activity but partially or completely results from an impaired mitochondrial antibacterial effector function. Since pharmacological inhibition of the respiratory chain raised the generation of ROI but nevertheless phenocopied the effect of hypoxia, ROI can be excluded as the mechanism underlying the antimicrobial activity of mitochondria.

scholarly journals Enterococcus faecalis Enhances Expression and Activity of the Enterohemorrhagic Escherichia coli Type III Secretion System

mBio ◽  
2019 ◽  
Vol 10 (6) ◽  
Author(s):  
Elizabeth A. Cameron ◽  
Vanessa Sperandio ◽  
Gary M. Dunny
Keyword(s):  
Enterococcus Faecalis ◽  
Type Iii Secretion ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Host Cells ◽  
Cell Contact ◽  
Content Type ◽  
E Coli ◽  
Type Iii ◽  
Expression And Activity

ABSTRACT The gut microbiota can significantly impact invading pathogens and the disease they cause; however, many of the mechanisms that dictate commensal-pathogen interactions remain unclear. Enterohemorrhagic Escherichia coli (EHEC) is a potentially lethal human intestinal pathogen that uses microbiota-derived molecules as cues to efficiently regulate virulence factor expression. Here, we investigate the interaction between EHEC and Enterococcus faecalis, a common human gut commensal, and show that E. faecalis affects both expression and activity of the EHEC type III secretion system (T3SS) via two distinct mechanisms. First, in the presence of E. faecalis there is increased transcription of genes encoding the EHEC T3SS. This leads to increased effector translocation and ultimately greater numbers of pedestals formed on host cells. The same effect was observed with several strains of enterococci, suggesting that it is a general characteristic of this group. In a mechanism separate from E. faecalis-induced transcription of the T3SS, we report that an E. faecalis-secreted protease, GelE, cleaves a critical structural component of the EHEC T3SS, EspB. Our data suggest that this cleavage actually increases effector translocation by the T3SS, supporting a model where EspB proteolysis promotes maximum T3SS activity. Finally, we report that treatment of EHEC with E. faecalis-conditioned cell-free medium is insufficient to induce increased T3SS expression, suggesting that this effect relies on cell contact between E. faecalis and EHEC. This work demonstrates a complex interaction between a human commensal and pathogen that impacts both expression and function of a critical virulence factor. IMPORTANCE This work reveals a complex and multifaceted interaction between a human gut commensal, Enterococcus faecalis, and a pathogen, enterohemorrhagic E. coli. We demonstrate that E. faecalis enhances expression of the enterohemorrhagic E. coli type III secretion system and that this effect likely depends on cell contact between the commensal and the pathogen. Additionally, the GelE protease secreted by E. faecalis cleaves a critical structural component of the EHEC type III secretion system. In agreement with previous studies, we find that this cleavage actually increases effector protein delivery into host cells by the secretion system. This work demonstrates that commensal bacteria can significantly shape expression and activity of pathogen virulence factors, which may ultimately shape the progression of disease.

The E. coli Whole-Cell Modeling Project

EcoSal Plus ◽  
2021 ◽  
Author(s):  
Gwanggyu Sun ◽  
Travis A. Ahn-Horst ◽  
Markus W. Covert
Keyword(s):  
Computational Model ◽  
Model Organism ◽  
Current Version ◽  
Whole Cell ◽  
Content Type ◽  
E Coli ◽  
Cell Modeling

The Escherichia coli whole-cell modeling project seeks to create the most detailed computational model of an E. coli cell in order to better understand and predict the behavior of this model organism. Details about the approach, framework, and current version of the model are discussed.

scholarly journals Purification and Host Specificity of Predatory Halobacteriovorax Isolates from Seawater

2015 ◽  
Vol 82 (3) ◽  
pp. 922-927 ◽  
Author(s):  
Gary P. Richards ◽  
Johnna P. Fay ◽  
Joseph Uknalis ◽  
O. Modesto Olanya ◽  
Michael A. Watson
Keyword(s):  
Host Specificity ◽  
Vibrio Vulnificus ◽  
Plaque Assay ◽  
Tidal River ◽  
Host Cells ◽  
Content Type ◽  
E Coli ◽  
Cultural Methods ◽  
Serovar Typhimurium ◽  
Salinity Levels

ABSTRACTHalobacteriovorax(formerlyBacteriovorax) is a small predatory bacterium found in the marine environment and modulates bacterial pathogens in shellfish. Four strains ofHalobacteriovoraxoriginally isolated inVibrio parahaemolyticusO3:K6 host cells were separated from their prey by an enrichment-filtration-dilution technique for specificity testing in other bacteria. This technique was essential, since 0.45-μm filtration alone was unable to remove infectiousVibriominicells, as determined by scanning electron microscopy and cultural methods. PurifiedHalobacteriovoraxstrains were screened for predation against otherV. parahaemolyticusstrains and againstVibrio vulnificus,Vibrio alginolyticus,Escherichia coliO157:H7, andSalmonella entericaserovar Typhimurium DT104, all potential threats to seafood safety. They showed high host specificity and were predatory only against strains ofV. parahaemolyticus. In addition, strains ofHalobacteriovoraxthat were predatory forE. coliO157:H7 andS. Typhimurium DT104 were isolated from a tidal river at 5 ppt salinity. In a modified plaque assay agar, they killed their respective prey over a broad range of salinities (5 to 30 ppt). Plaques became smaller as the salinity levels rose, suggesting that the lower salinities were optimal for the predators' replication. These species also showed broader host specificity, infectious against each other's original hosts as well as againstV. parahaemolyticusstrains. In summary, this study characterized strains ofHalobacteriovoraxwhich may be considered for use in the development of broad-based biocontrol technologies to enhance the safety of commercially marketed shellfish and other foods.

scholarly journals High-Level Heterologous Production of d-Cycloserine by Escherichia coli

2015 ◽  
Vol 81 (22) ◽  
pp. 7881-7887 ◽  
Author(s):  
Takanori Kumagai ◽  
Tomoki Ozawa ◽  
Momoko Tanimoto ◽  
Masafumi Noda ◽  
Yasuyuki Matoba ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Host Cells ◽  
Resting Cells ◽  
Knockout Mutant ◽  
Double Knockout ◽  
Biosynthetic Genes ◽  
T7 Promoter ◽  
Α Subunit ◽  
Content Type ◽  
E Coli

ABSTRACTPreviously, we successfully cloned ad-cycloserine (d-CS) biosynthetic gene cluster consisting of 10 open reading frames (designateddcsAtodcsJ) fromd-CS-producingStreptomyces lavendulaeATCC 11924. In this study, we put fourd-CS biosynthetic genes (dcsC,dcsD,dcsE, anddcsG) in tandem under the control of the T7 promoter in anEscherichia colihost. SDS-PAGE analysis demonstrated that the 4 gene products were simultaneously expressed in host cells. Whenl-serine and hydroxyurea (HU), the precursors ofd-CS, were incubated together with theE. coliresting cell suspension, the cells produced significant amounts ofd-CS (350 ± 20 μM). To increase the productivity ofd-CS, thedcsJgene, which might be responsible for thed-CS excretion, was connected downstream of the four genes. TheE. coliresting cells harboring the five genes producedd-CS at 660 ± 31 μM. ThedcsDgene product, DcsD, formsO-ureido-l-serine fromO-acetyl-l-serine (OAS) and HU, which are intermediates ind-CS biosynthesis. DcsD also catalyzes the formation ofl-cysteine from OAS and H2S. To repress the side catalytic activity of DcsD, theE. colichromosomalcysJandcysKgenes, encoding the sulfite reductase α subunit and OAS sulfhydrylase, respectively, were disrupted. When resting cells of the double-knockout mutant harboring the fourd-CS biosynthetic genes, together withdcsJ, were incubated withl-serine and HU, thed-CS production was 980 ± 57 μM, which is comparable to that ofd-CS-producingS. lavendulaeATCC 11924 (930 ± 36 μM).

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