scholarly journals A miniaturized biotyping system for strain discrimination inEscherichia coli

1993 ◽  
Vol 111 (1) ◽  
pp. 81-88
Author(s):  
P. B. Crichton ◽  
J. M. J. Logan ◽  
D. C. Old
Keyword(s):  
Escherichia Coli ◽  
Efficient Method ◽  
High Index ◽  
Inescherichia Coli ◽  
E Coli

SummaryA two-tier miniaturized scheme of eight tests was devised for biotyping strains ofEscherichia coliin microwell plates. Primary biotypes were defined by positive and negative reactions in tests for fermentation of raffinose, sorbose, dulcitol and 2-deoxy-D-ribose and for decarboxylation of ornithine when read after specified periods of incubation; subtypes were identified within primary biotypes according to results in secondary tests for rhamnose fermentation, lysine decarboxylation and motility. The method gave reproducible results on different occasions of testing.Among 100E. colistrains from various sources, 26 of the 32 possible primary biotypes and 56 full biotypes, as defined by results in both primary and secondary tests, were identified, thus demonstrating a high index of strain discrimination (D = 0·98).The scheme is recommended as a simple, reliable, inexpensive and efficient method of differentiating strains ofE. coli.

Evaluation of Structurally Different Carotenoids inEscherichia coli Transformants as Protectants against UV-B Radiation

1998 ◽  
Vol 64 (5) ◽  
pp. 1972-1974 ◽  
Author(s):  
Gerhard Sandmann ◽  
Silvia Kuhn ◽  
Peter B�ger
Keyword(s):  
Escherichia Coli ◽  
Inescherichia Coli ◽  
Short Term ◽  
E Coli ◽  
Carotenogenic Genes ◽  
Β Carotene

ABSTRACT Escherichia coli cells transformed with several carotenogenic genes to mediate the formation of ζ-carotene, neurosporene, lycopene, β-carotene, and zeaxanthin were exposed to UV-B radiation. Short-term kinetics revealed that endogenous levels of neurosporene and β-carotene protected E. coli against irradiation with UV-B. Zeaxanthin protected against only the photosensitized UV-B treatment. All other carotenoids were ineffective.

scholarly journals DNA Microarray-Based Identification of Genes Controlled by Autoinducer 2-Stimulated Quorum Sensing inEscherichia coli

2001 ◽  
Vol 183 (18) ◽  
pp. 5239-5247 ◽  
Author(s):  
Matthew P. DeLisa ◽  
Chi-Fang Wu ◽  
Liang Wang ◽  
James J. Valdes ◽  
William E. Bentley
Keyword(s):  
Escherichia Coli ◽  
Quorum Sensing ◽  
Cell Communication ◽  
Global Changes ◽  
Dependent Manner ◽  
Inescherichia Coli ◽  
E Coli ◽  
Autoinducer 2 ◽  
Coordinated Expression ◽  
Transcriptional Changes

ABSTRACT Bacterial cell-to-cell communication facilitates coordinated expression of specific genes in a growth rate-II and cell density-dependent manner, a process known as quorum sensing. While the discovery of a diffusible Escherichia coli signaling pheromone, termed autoinducer 2 (AI-2), has been made along with several quorum sensing genes, the overall number and coordination of genes controlled by quorum sensing through the AI-2 signal has not been studied systematically. We investigated global changes in mRNA abundance elicited by the AI-2 signaling molecule through the use of aluxS mutant that was unable to synthesize AI-2. Remarkably, 242 genes, comprising ca. 5.6% of the E. coli genome, exhibited significant transcriptional changes (either induction or repression) in response to a 300-fold AI-2 signaling differential, with many of the identified genes displaying high induction levels (more than fivefold). Significant induction of ygeV, a putative ς54-dependent transcriptional activator, andyhbH, a ς54 modulating protein, suggests ς54 may be involved in E. coli quorum sensing.

scholarly journals Muropeptides Stimulate Growth Resumption from Stationary Phase inEscherichia coli

2019 ◽  
Author(s):  
Arvi Jõers ◽  
Kristiina Vind ◽  
Sara B. Hernández ◽  
Regina Maruste ◽  
Marta Pereira ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Metabolic Activity ◽  
Microbial Growth ◽  
Peptide Bond ◽  
Bacterial Spores ◽  
Inescherichia Coli ◽  
E Coli ◽  
Growth Promoting ◽  
Previous Identification

AbstractWhen nutrients run out, bacteria enter a dormant metabolic state. This low or undetectable metabolic activity helps bacteria to preserve their scant reserves for future, but also diminishes their ability to trace the environment for new growth-promoting substrates. However, neighboring microbial growth is a sure indicator of favorable environment and thus, can serve as a cue for exiting the dormancy. Here we report that forEscherichia colithis cue is the basic peptidoglycan unit (i.e. muropeptide). We show that several forms of muropeptides can stimulate growth resumption of dormantE. colicells, but the sugar – peptide bond is crucial for activity. We also demonstrate that muropeptides from several different species can induce growth resumption ofE. coliand alsoPseudomonas aeruginosa. These results, together with the previous identification of muropeptides as germination signal for bacterial spores, makes muropeptides rather universal cue for bacterial growth.

scholarly journals Expression of the Mitochondrial ADP/ATP Carrier inEscherichia coli

2001 ◽  
Vol 276 (15) ◽  
pp. 11499-11506 ◽  
Author(s):  
Simone Heimpel ◽  
Gabriele Basset ◽  
Sabine Odoy ◽  
Martin Klingenberg
Keyword(s):  
Escherichia Coli ◽  
Saccharomyces Cerevisiae ◽  
Inclusion Bodies ◽  
Positive Charge ◽  
Inescherichia Coli ◽  
Transport Activity ◽  
E Coli ◽  
The Matrix ◽  
A Charge

Previously, the role of residues in the ADP/ATP carrier (AAC) fromSaccharomyces cerevisiaehas been studied by mutagenesis, but the dependence of mitochondrial biogenesis on functional AAC impedes segregation of the mutational effects on transport and biogenesis. Unlike other mitochondrial carriers, expression of the AAC from yeast or mammalians inEscherichia coliencountered difficulties because of disparate codon usage. Here we introduce the AAC fromNeurospora crassainE. coli, where it is accumulated in inclusion bodies and establish the reconstitution conditions. AAC expressed with heat shock vector gave higher activity than with pET-3a. Transport activity was absolutely dependent on cardiolipin. The 10 single mutations of intrahelical positive residues and of the matrix repeat (+X+) motif resulted in lower activity, except of R245A. R143A had decreased sensitivity toward carboxyatractylate. The ATP-linked exchange is generally more affected than ADP exchange. This reflects a charge network that propagates positive charge defects to ATP4−more strongly than to ADP3−transport. Comparison to the homologous mutants of yeast AAC2 permits attribution of the roles of these residues more to ADP/ATP transport or to AAC import into mitochondria.

scholarly journals Simple and Efficient Method for Heterologous Expression of Clostridial Proteins

2000 ◽  
Vol 66 (8) ◽  
pp. 3166-3173 ◽  
Author(s):  
Alexey G. Zdanovsky ◽  
Marina V. Zdanovskaia
Keyword(s):  
Escherichia Coli ◽  
Efficient Method ◽  
Protein Production ◽  
Trna Gene ◽  
Trna Genes ◽  
Coding Sequences ◽  
E Coli ◽  
Rare Codons ◽  
Novel Approach ◽  
Moderate Effect

ABSTRACT Many clostridial proteins are poorly produced in Escherichia coli. It has been suggested that this phenomena is due to the fact that several types of codons common in clostridial coding sequences are rarely used in E. coli and the quantities of the corresponding tRNAs in E. coli are not sufficient to ensure efficient translation of the corresponding clostridial sequences. To address this issue, we amplified three E. coli genes, ileX, argU, andleuW, in E. coli; these genes encode tRNAs that are rarely used in E. coli (the tRNAs for the ATA, AGA, and CTA codons, respectively). Our data demonstrate that amplification ofileX dramatically increased the level of production of most of the clostridial proteins tested, while amplification ofargU had a moderate effect and amplification ofleuW had no effect. Thus, amplification of certain tRNA genes for rare codons in E. coli improves the expression of clostridial genes in E. coli, while amplification of other tRNAs for rare codons might not be needed for improved expression. We also show that amplification of a particular tRNA gene might have different effects on the level of protein production depending on the prevalence and relative positions of the corresponding codons in the coding sequence. Finally, we describe a novel approach for improving expression of recombinant clostridial proteins that are usually expressed at a very low level in E. coli.

scholarly journals FabG, an NADPH-Dependent 3-Ketoacyl Reductase ofPseudomonas aeruginosa, Provides Precursors for Medium-Chain-Length Poly-3-Hydroxyalkanoate Biosynthesis inEscherichia coli

2000 ◽  
Vol 182 (10) ◽  
pp. 2978-2981 ◽  
Author(s):  
Qun Ren ◽  
Nicolas Sierro ◽  
Bernard Witholt ◽  
Birgit Kessler
Keyword(s):  
Escherichia Coli ◽  
Chain Length ◽  
Reductase Activity ◽  
Inescherichia Coli ◽  
E Coli ◽  
Medium Chain ◽  
Medium Chain Length ◽  
Encoding Gene ◽  
Coa Reductase ◽  
Formation Step

ABSTRACT Escherichia coli hosts expressing fabG ofPseudomonas aeruginosa showed 3-ketoacyl coenzyme A (CoA) reductase activity toward R-3-hydroxyoctanoyl-CoA. Furthermore, E. coli recombinants carrying the poly-3-hydroxyalkanoate (PHA) polymerase-encoding gene phaCin addition to fabG accumulated medium-chain-length PHAs (mcl-PHAs) from alkanoates. When E. coli fadB orfadA mutants, which are deficient in steps downstream or upstream of the 3-ketoacyl-CoA formation step during β-oxidation, respectively, were transformed with fabG, higher levels of PHA were synthesized in E. coli fadA, whereas similar levels of PHA were found in E. coli fadB, compared with those of the corresponding mutants carrying phaC alone. These results strongly suggest that FabG of P. aeruginosais able to reduce mcl-3-ketoacyl-CoAs generated by the β-oxidation to 3-hydroxyacyl-CoAs to provide precursors for the PHA polymerase.

scholarly journals Apramycin resistance plasmids inEscherichia coli: possible transfer toSalmonella typhimuriumin calves

1992 ◽  
Vol 108 (2) ◽  
pp. 271-278 ◽  
Author(s):  
J. E. B. Hunter ◽  
J. C. Shelley ◽  
J. R. Walton ◽  
C. A. Hart ◽  
M. Bennett
Keyword(s):  
Escherichia Coli ◽  
Salmonella Typhimurium ◽  
High Frequency ◽  
Inescherichia Coli ◽  
Gene Encoding ◽  
E Coli ◽  
Resistance Plasmids ◽  
Effect Of Treatment ◽  
K 12

SUMMARYAn outbreak of salmonellosis in calves was monitored for persistence ofSalmonella typhimuriumexcretion in faeces and the effect of treatment with apramycin. Prior to treatment apramycin-resistantEscherichia coliwere present but allS. typhimuriumisolates were sensitive. Following the treatment of six calves with apramycin, apramycin-resistantS. typhimuriumwere isolated from two treated calves and one untreated calf. Plasmid profiles ofE. coliandS. typhimuriumwere compared and plasmids conferring resistance to apramycin and several other antibiotics were transferred by conjugationin vitrofrom calfE. coliandS. typhimuriumisolates toE. coliK-12 and fromE. colitoS. typhimurium. The plasmids conjugated with high frequencyin vitrofromE. colitoS. typhimurium, and hybridized to a DNA probe specific for the gene encoding aminoglycoside acetyltransferase 3-IV (AAC(3)-IV) which confers resistance to apramycin, gentamicin, netilmicin and tobramycin.

scholarly journals Cloning, Purification, and Partial Characterization ofBacillus subtilisUrate Oxidase Expressed inEscherichia coli

2010 ◽  
Vol 2010 ◽  
pp. 1-6 ◽  
Author(s):  
Pollyana Pfrimer ◽  
Lidia Maria Pepe de Moraes ◽  
Alexsandro Sobreira Galdino ◽  
Loise Pedrosa Salles ◽  
Viviane Castelo Branco Reis ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Time Course ◽  
Single Step ◽  
Urate Oxidase ◽  
Inescherichia Coli ◽  
E Coli ◽  
Gene Coding ◽  
Step Procedure ◽  
Diagnostic Reagent ◽  
Optimal Ph

Urate oxidase (EC 1.7.3.3) is an enzyme involved in purine metabolism which is used in the treatment of gout and as diagnostic reagent for detection of uric acid. In order to produce this enzyme in large quantities for biotechnological purposes, the gene coding for theBacillus subtilisurate oxidase was cloned and heterologously expressed inEscherichia coli. Time course induction inE. colishowed an induced protein with an apparent molecular mass of∼60 kDa. Soluble recombinant enzyme was purified in a single-step procedure using Ni-NTA column. The enzyme was purified 2.1-fold with a yield of 56% compared to the crude extract. MALDI-TOF analysis revealed an ion with a mass of 58675 Da which is in agreement with the expected mass of the recombinant protein. The purified enzyme showed an optimal pH and temperature of 8.0 and37∘C, respectively, and retained 90% of its activity after 72 hours of incubation at −20∘Cand4∘C.

scholarly journals Rsd balances (p)ppGpp level by stimulating the hydrolase activity of SpoT during carbon source downshift inEscherichia coli

2018 ◽  
Vol 115 (29) ◽  
pp. E6845-E6854 ◽  
Author(s):  
Jae-Woo Lee ◽  
Young-Ha Park ◽  
Yeong-Jae Seok
Keyword(s):  
Escherichia Coli ◽  
Carbon Source ◽  
Control Mechanism ◽  
Stringent Response ◽  
Hydrolase Activity ◽  
Inescherichia Coli ◽  
Phosphotransferase System ◽  
E Coli ◽  
Cellular Concentration ◽  
Spot Activity

Bacteria respond to nutritional stresses by changing the cellular concentration of the alarmone (p)ppGpp. This control mechanism, called the stringent response, depends on two enzymes, the (p)ppGpp synthetase RelA and the bifunctional (p)ppGpp synthetase/hydrolase SpoT inEscherichia coliand related bacteria. Because SpoT is the only enzyme responsible for (p)ppGpp hydrolysis in these bacteria, SpoT activity needs to be tightly regulated to prevent the uncontrolled accumulation of (p)ppGpp, which is lethal. To date, however, no such regulation of SpoT (p)ppGpp hydrolase activity has been documented inE. coli. In this study, we show that Rsd directly interacts with SpoT and stimulates its (p)ppGpp hydrolase activity. Dephosphorylated HPr, but not phosphorylated HPr, of the phosphoenolpyruvate-dependent sugar phosphotransferase system could antagonize the stimulatory effect of Rsd on SpoT (p)ppGpp hydrolase activity. Thus, we suggest that Rsd is a carbon source-dependent regulator of the stringent response inE. coli.

KINETIC MODELING OFACEOPERON GENETIC REGULATION INESCHERICHIA COLI

2008 ◽  
Vol 06 (05) ◽  
pp. 933-959 ◽  
Author(s):  
KIRILL PESKOV ◽  
IGOR GORYANIN ◽  
KLAUS PRANK ◽  
FRANK TOBIN ◽  
OLEG DEMIN
Keyword(s):  
Escherichia Coli ◽  
Binding Sites ◽  
Genetic Regulation ◽  
Experimental Information ◽  
Literature Analysis ◽  
Inescherichia Coli ◽  
Main Aspect ◽  
E Coli ◽  
Expression In Escherichia Coli ◽  
Operon Expression

A family of kinetic models has been developed that takes into account available experimental information on the regulation of ace operon expression in Escherichia coli. This has allowed us to study and analyze possible versions of regulation of the ace operon and to test their possibilities. Based on literature analysis, we found that there is an ambiguity of properties of IclR (main repressor of ace operon). The main aspect of this ambiguity are two different forms of IclR purified from E. coli K strain and different coeffector sets for IclR purified from E. coli K and B strains. It has been shown that the full-length form of IclR is physiologically relevant and that IclR truncation is a result of purification of the protein from E. coli K strains. We also found that the IclR protein purified from E. coli B strain carries two coeffector binding sites. Using model-developed levels of steady state aceBAK expression against physiological ranges of coeffectors, concentration has been predicted.

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