Comparison of faecal and optimal growth conditions on in vitro pharmacodynamic activity of marbofloxacin against Escherichia coli

2006 ◽  
Vol 80 (3) ◽  
pp. 324-335 ◽  
Author(s):  
T. Pellet ◽  
M. Gicquel-Bruneau ◽  
P. Sanders ◽  
M. Laurentie
Keyword(s):  
Escherichia Coli ◽  
Optimal Growth ◽  
Growth Conditions

scholarly journals A Rhodobacter sphaeroides Protein Mechanistically Similar to Escherichia coli DksA Regulates Photosynthetic Growth

mBio ◽  
2014 ◽  
Vol 5 (3) ◽  
Author(s):  
Christopher W. Lennon ◽  
Kimberly C. Lemmer ◽  
Jessica L. Irons ◽  
Max I. Sellman ◽  
Timothy J. Donohue ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Structure Function ◽  
Rhodobacter Sphaeroides ◽  
Fatty Acid Content ◽  
Regulatory Protein ◽  
Growth Conditions ◽  
Globular Domain ◽  
Content Type ◽  
E Coli

ABSTRACTDksA is a global regulatory protein that, together with the alarmone ppGpp, is required for the “stringent response” to nutrient starvation in the gammaproteobacteriumEscherichia coliand for more moderate shifts between growth conditions. DksA modulates the expression of hundreds of genes, directly or indirectly. Mutants lacking a DksA homolog exhibit pleiotropic phenotypes in other gammaproteobacteria as well. Here we analyzed the DksA homolog RSP2654 in the more distantly relatedRhodobacter sphaeroides, an alphaproteobacterium. RSP2654 is 42% identical and similar in length toE. coliDksA but lacks the Zn finger motif of theE. coliDksA globular domain. Deletion of the RSP2654 gene results in defects in photosynthetic growth, impaired utilization of amino acids, and an increase in fatty acid content. RSP2654 complements the growth and regulatory defects of anE. colistrain lacking thedksAgene and modulates transcriptionin vitrowithE. coliRNA polymerase (RNAP) similarly toE. coliDksA. RSP2654 reduces RNAP-promoter complex stabilityin vitrowith RNAPs fromE. coliorR. sphaeroides, alone and synergistically with ppGpp, suggesting that even though it has limited sequence identity toE. coliDksA (DksAEc), it functions in a mechanistically similar manner. We therefore designate the RSP2654 protein DksARsp. Our work suggests that DksARsphas distinct and important physiological roles in alphaproteobacteria and will be useful for understanding structure-function relationships in DksA and the mechanism of synergy between DksA and ppGpp.IMPORTANCEThe role of DksA has been analyzed primarily in the gammaproteobacteria, in which it is best understood for its role in control of the synthesis of the translation apparatus and amino acid biosynthesis. Our work suggests that DksA plays distinct and important physiological roles in alphaproteobacteria, including the control of photosynthesis inRhodobacter sphaeroides. The study of DksARsp, should be useful for understanding structure-function relationships in the protein, including those that play a role in the little-understood synergy between DksA and ppGpp.

scholarly journals The Escherichia coli cysG promoter belongs to the ‘extended −10’ class of bacterial promoters

1993 ◽  
Vol 296 (3) ◽  
pp. 851-857 ◽  
Author(s):  
T Belyaeva ◽  
L Griffiths ◽  
S Minchin ◽  
J Cole ◽  
S Busby
Keyword(s):  
Escherichia Coli ◽  
Point Mutations ◽  
Growth Conditions ◽  
Upstream Region ◽  
E Coli ◽  
Run Off ◽  
A Site ◽  
Specific Sequences

The Escherichia coli cysG promoter has been subcloned and shown to function constitutively in a range of different growth conditions. Point mutations identify the -10 hexamer and an important 5′-TGN-3′ motif immediately upstream. The effects of different deletions suggest that specific sequences in the -35 region are not essential for the activity of this promoter in vivo. This conclusion was confirmed by in vitro run-off transcription assays. The DNAase I footprint of RNA polymerase at the cysG promoter reveals extended protection upstream of the transcript start, and studies with potassium permanganate as a probe suggest that the upstream region is distorted in open complexes. Taken together, the results show that the cysG promoter belongs to the ‘extended -10’ class of promoters, and the base sequence is similar to that of the P1 promoter of the E. coli galactose operon, another promoter in this class. In vivo, messenger initiated at the cysG promoter appears to be processed by cleavage at a site 41 bases downstream from the transcript start point.

scholarly journals Identification and Regulation of a Novel Citrobacter rodentium Gut Colonization Fimbria (Gcf)

2015 ◽  
Vol 197 (8) ◽  
pp. 1478-1491 ◽  
Author(s):  
Gustavo G. Caballero-Flores ◽  
Matthew A. Croxen ◽  
Verónica I. Martínez-Santos ◽  
B. Brett Finlay ◽  
José L. Puente
Keyword(s):  
Escherichia Coli ◽  
Intestinal Epithelium ◽  
Pathogenic Bacteria ◽  
Critical Role ◽  
Growth Conditions ◽  
Citrobacter Rodentium ◽  
Content Type ◽  
Gut Colonization ◽  
Successful Infection

ABSTRACTThe Gram-negative enteric bacteriumCitrobacter rodentiumis a natural mouse pathogen that has been extensively used as a surrogate model for studying the human pathogens enteropathogenic and enterohemorrhagicEscherichia coli. All three pathogens produce similar attaching and effacing (A/E) lesions in the intestinal epithelium. During infection, these bacteria employ surface structures called fimbriae to adhere and colonize the host intestinal epithelium. ForC. rodentium, the roles of only a small number of its genome-carried fimbrial operons have been evaluated. Here, we report the identification of a novelC. rodentiumcolonization factor, calledgutcolonizationfimbria (Gcf), which is encoded by a chaperone-usher fimbrial operon. AgcfAmutant shows a severe colonization defect within the first 10 days of infection. Thegcfpromoter is not active inC. rodentiumunder severalin vitrogrowth conditions; however, it is readily expressed in aC. rodentiumΔhns1mutant lacking the closest ortholog of theEscherichia colihistone-like nucleoid structuring protein (H-NS) but not in mutants with deletion of the other four genes encoding H-NS homologs. H-NS binds to the regulatory region ofgcf, further supporting its direct role as a repressor of thegcfpromoter that starts transcription 158 bp upstream of the start codon of its first open reading frame. Thegcfoperon possesses interesting novel traits that open future opportunities to expand our knowledge of the structure, regulation, and function during infection of these important bacterial structures.IMPORTANCEFimbriae are surface bacterial structures implicated in a variety of biological processes. Some have been shown to play a critical role during host colonization and thus in disease. Pathogenic bacteria possess the genetic information for an assortment of fimbriae, but their function and regulation and the interplay between them have not been studied in detail. This work provides new insights into the function and regulation of a novel fimbria called Gcf that is important for early establishment of a successful infection byC. rodentiumin mice, despite being poorly expressed underin vitrogrowth conditions. This discovery offers an opportunity to better understand the individual role and the regulatory mechanisms controlling the expression of specific fimbrial operons that are critical during infection.

scholarly journals Chicken gut microbiome members limit the spread of an antimicrobial resistance plasmid in Escherichia coli

2021 ◽  
Vol 288 (1962) ◽  
Author(s):  
Sarah J. N. Duxbury ◽  
Jesse B. Alderliesten ◽  
Mark P. Zwart ◽  
Arjan Stegeman ◽  
Egil A. J. Fischer ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Resistance ◽  
Horizontal Transmission ◽  
Growth Conditions ◽  
Plasmid Transfer ◽  
Microbial Interactions ◽  
Transfer Rates ◽  
Resistance Plasmid ◽  
Mating Opportunities

Plasmid-mediated antimicrobial resistance is a major contributor to the spread of resistance genes within bacterial communities. Successful plasmid spread depends upon a balance between plasmid fitness effects on the host and rates of horizontal transmission. While these key parameters are readily quantified in vitro , the influence of interactions with other microbiome members is largely unknown. Here, we investigated the influence of three genera of lactic acid bacteria (LAB) derived from the chicken gastrointestinal microbiome on the spread of an epidemic narrow-range ESBL resistance plasmid, IncI1 carrying bla CTX-M-1 , in mixed cultures of isogenic Escherichia coli strains. Secreted products of LAB decreased E. coli growth rates in a genus-specific manner but did not affect plasmid transfer rates. Importantly, we quantified plasmid transfer rates by controlling for density-dependent mating opportunities. Parametrization of a mathematical model with our in vitro estimates illustrated that small fitness costs of plasmid carriage may tip the balance towards plasmid loss under growth conditions in the gastrointestinal tract. This work shows that microbial interactions can influence plasmid success and provides an experimental-theoretical framework for further study of plasmid transfer in a microbiome context.

scholarly journals Introduction to in vitro culture of Ginkgo biloba (Linnaeus, 1771)

2020 ◽  
Vol 203 (12) ◽  
pp. 43-49
Author(s):  
Varvara Bessonova ◽  
Ol'ga Cherepanova
Keyword(s):  
Ginkgo Biloba ◽  
Optimal Growth ◽  
Growth Conditions ◽  
Biologically Active ◽  
Future Research ◽  
Planting Material ◽  
Murashige Skoog ◽  
Young Leaves ◽  
High Proliferative Activity

Abstract. The purpose of this research was to introduce Ginkgo biloba into culture, to study the composition and properties of its biologically active compounds. Methods. We researched the optimal growth conditions for obtaining a viable tissue culture, such as: concentration of phytohormones and other organic and nonorganic substances in Murashige – Skoog medium and light hours. The effectiveness of the standard method of sodium hypochloride sterilization of young leaves and vegetative buds also was verified. As a result, of conducting the experiment we were able to grow a living callus from leaves of G. biloba. Based on this result we can conclude that these conditions are acceptable for high proliferative activity of the plant. We were studied the effect of phytohormones NAA, at a concentration of 0.5 ml and 6-BAP, at a concentration of 2.5 ml. Also, was selected the ideal planting material for callus production – young leaves that were more sensitive to treatment with hypochloride. This research serves as the foundation for future research not only for our laboratory, but also for other research groups. The callus can be used to clone specimens of G. bilobain greenhouses. It will be use to extract and study unique chemical compounds, such as ginkgolides, bilobalides and various terpenes, contained in the extract of plants of this group.

scholarly journals Effect of environment on the evolutionary trajectories and growth characteristics of antibiotic-resistant Escherichia coli mutants

2018 ◽  
Author(s):  
Alasdair T. M. Hubbard ◽  
Nazila V. Jafari ◽  
Nicholas Feasey ◽  
Jennifer L. Rohn ◽  
Adam P. Roberts
Keyword(s):  
Escherichia Coli ◽  
Diagnostic Testing ◽  
Diagnostic Procedures ◽  
Growth Conditions ◽  
Media Type ◽  
Artificial Environment ◽  
The Face ◽  
Bacterial Fitness

AbstractIn the face of an accelerating global antimicrobial resistance crisis, the determination of bacterial fitness following acquisition of resistance is an expanding area of research, and increased understanding of this process will be crucial to translate in vitro fitness data to successful therapies. Given that crucial clinical treatment situations are guided by in vitro diagnostic testing in an artificial environment far removed from human physiological niches, we used Escherichia coli and amoxicillin-clavulanic acid (AMC) resistance as a model to understand how such environments could affect the emergence of resistance, associated fitness costs and the predictive value of this data when strains were grown in the more physiologically relevant environments of urine and urothelial organoids. Resistant E. coli isolates were selected for following 24-hour exposure to sub-inhibitory concentrations of AMC in either M9, ISO or LB broth, followed by growth on LB agar containing AMC. No resistant colonies emerged following growth in M9, whereas resistant isolates were detected from cultures grown in ISO and LB broth. We observed both within and between media-type variability in the levels of resistance and fitness of the resistant mutants grown in LB. MICs and fitness of these resistant strains in different media (M9, ISO, LB, human urine and urothelial organoids) showed considerable variation. Media can therefore have a direct effect on the isolation of mutants that confer resistance to AMC and these mutants can exhibit unpredictable MIC and fitness profiles under different growth conditions. This study highlights the risks in relying on a single culture protocol to predict the behaviour and treatment response of bacteria in vivo and highlights the importance of developing comprehensive experimental designs to ensure effective translation of diagnostic procedures to successful clinical outcomes.

scholarly journals Bicarbonate Ion Stimulates the Expression of Locus of Enterocyte Effacement-Encoded Genes in Enterohemorrhagic Escherichia coli O157:H7

2002 ◽  
Vol 70 (7) ◽  
pp. 3500-3509 ◽  
Author(s):  
Hiroyuki Abe ◽  
Ichiro Tatsuno ◽  
Toru Tobe ◽  
Akiko Okutani ◽  
Chihiro Sasakawa
Keyword(s):  
Escherichia Coli ◽  
Intestinal Tract ◽  
Optimal Growth ◽  
Growth Conditions ◽  
Luria Bertani ◽  
Enterohemorrhagic Escherichia Coli ◽  
Bacterial Adherence ◽  
Escherichia Coli O157 ◽  
Factors Affecting ◽  
Enterocyte Effacement

ABSTRACT Enterohemorrhagic Escherichia coli (EHEC) strains adhere to the intestinal mucosa and produce an attaching and effacing (A/E) lesion. Most of the genes required to produce A/E lesions are thought to be encoded by the 36-kb pathogenicity island termed the locus for enterocyte effacement (LEE). Although the mechanisms underlying the bacterial adherence, including the genes involved, are still poorly understood, the preferential adherence phenotype of EHEC is thought to depend on the nature of the genes and/or the response of these genes to changes in environmental conditions. To explore the environmental factors affecting EHEC adherence, we used an O157:H7 strain and investigated the optimal growth conditions for its adherence to Caco-2 cells. We observed that EHEC grown in Dulbecco's modified Eagle's medium (DMEM) adhered more efficiently to Caco-2 cells than EHEC grown in Luria-Bertani (LB) broth. Among the components of DMEM, only NaHCO3 was found to remarkably stimulate bacterial adherence. When bacteria were grown in LB broth containing NaHCO3, the production of intimin, Tir, EspA, and EspB was greatly enhanced compared with the production in LB broth. Indeed, the transcription of ler required for LEE-encoded gene expression was promoted in response to the concentration of NaHCO3 in LB broth. Since the concentration of NaHCO3 in the lower intestinal tract has been shown to be relatively high compared with that in the upper small intestine, our results may imply that NaHCO3 is an important signaling factor for promoting colonization of EHEC in the lower intestinal tract in humans.

Effects of antecedent fermentative and respiratory growth on the detection of chloramine-stressed Escherichia coli and Salmonella typhimurium

2001 ◽  
Vol 47 (8) ◽  
pp. 777-781
Author(s):  
Richard L Thunberg ◽  
Alan J Sexstone ◽  
Joseph P Calabrese ◽  
Gary K Bissonnette
Keyword(s):  
Escherichia Coli ◽  
Salmonella Typhimurium ◽  
Growth Conditions ◽  
Time Intervals ◽  
Reducing Conditions ◽  
Test Organisms ◽  
Increased Sensitivity ◽  
T Values ◽  
Predetermined Time

In vitro laboratory studies were performed to assess the effects of antecedent growth conditions on the recovery of Escherichia coli ATCC 25922 and Salmonella typhimurium ATCC 14028 following chloramine disinfection. Six- and 18-h cultures of each organism were grown under aerobic, fermentative, and nitrate-reducing conditions prior to disinfection. At predetermined time intervals during a 10-min exposure to chloramine, survivors were surface plated on nonselective recovery media to determine Cnt values. It was observed that nitrate-reducing growth predisposed the test organisms towards an increased sensitivity to chloramine stress over cells grown under fermentation or aerobic conditions (p < 0.01).Key words: Escherichia coli, Salmonella typhimurium, chloramine, survival, antecedent growth conditions.

Sign in / Sign up

Export Citation Format

Share Document