TOXICITY OF COPPER TO ESCHERICHIA COLI IN RELATION TO INCUBATION TEMPERATURE AND METHOD OF STERILIZATION OF MEDIA

1967 ◽  
Vol 13 (10) ◽  
pp. 1299-1309 ◽  
Author(s):  
Carmen Melanie Wells Burke ◽  
Ilda McVeigh
Keyword(s):  
Experimental Data ◽  
Escherichia Coli ◽  
Growth Rate ◽  
Optical Density ◽  
Incubation Temperature ◽  
Synthetic Medium ◽  
E Coli ◽  
Viable Cells ◽  
Sterilization Process

The growth of Escherichia coli ATCC 9637 in a basal synthetic medium was very similar in cultures incubated at 35, 37, 40, and 42 °C. The inclusion in the medium of copper at concentrations of 0.1 and 0.2 μg/ml resulted in a decrease in the growth rate at each of these temperatures; the higher the temperature, the greater the decrease. Copper caused a decrease in the growth rate of E. coli in the medium sterilized by filtration as well as in that sterilized by autoclaving. However, in the medium sterilized by heat there were alternate periods in which the optical density (O.D.) of culture increased and periods during which no increase in O.D. occurred. Decreases of 50% or more in the numbers of viable cells occurred in conjunction with the plateaus in the O.D. of the cultures. A greater delay in the initiation of growth occurred in both the copper-free and the copper-containing media sterilized by heat than in the corresponding medium sterilized by filtration; the longer the exposure of the medium to heat during the sterilization process, the greater the delay in the initiation of growth. Several theories are presented and discussed as possible explanations of the experimental data obtained.

scholarly journals Molecular Control of Sucrose Utilization in Escherichia coli W, an Efficient Sucrose-Utilizing Strain

2012 ◽  
Vol 79 (2) ◽  
pp. 478-487 ◽  
Author(s):  
Suriana Sabri ◽  
Lars K. Nielsen ◽  
Claudia E. Vickers
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Good Growth ◽  
Knockout Mutant ◽  
Sucrose Transport ◽  
Molecular Control ◽  
Content Type ◽  
E Coli ◽  
K 12 ◽  
Sucrose Utilization

ABSTRACTSucrose is an industrially important carbon source for microbial fermentation. Sucrose utilization inEscherichia coli, however, is poorly understood, and most industrial strains cannot utilize sucrose. The roles of the chromosomally encoded sucrose catabolism (csc) genes inE. coliW were examined by knockout and overexpression experiments. At low sucrose concentrations, thecscgenes are repressed and cells cannot grow. Removal of either the repressor protein (cscR) or the fructokinase (cscK) gene facilitated derepression. Furthermore, combinatorial knockout ofcscRandcscKconferred an improved growth rate on low sucrose. The invertase (cscA) and sucrose transporter (cscB) genes are essential for sucrose catabolism inE. coliW, demonstrating that no other genes can provide sucrose transport or inversion activities. However,cscKis not essential for sucrose utilization. Fructose is excreted into the medium by thecscK-knockout strain in the presence of high sucrose, whereas at low sucrose (when carbon availability is limiting), fructose is utilized by the cell. Overexpression ofcscA,cscAK, orcscABcould complement the WΔcscRKABknockout mutant or confer growth on a K-12 strain which could not naturally utilize sucrose. However, phenotypic stability and relatively good growth rates were observed in the K-12 strain only when overexpressingcscAB, and full growth rate complementation in WΔcscRKABalso requiredcscAB. Our understanding of sucrose utilization can be used to improveE. coliW and engineer sucrose utilization in strains which do not naturally utilize sucrose, allowing substitution of sucrose for other, less desirable carbon sources in industrial fermentations.

scholarly journals Moringa oleifera Seeds Extract Activity on Enteropathogenic Escherichia coli and Aeromonas hydrophyla Cells in Aquatic Microcosm

2019 ◽  
Vol 7 (2) ◽  
pp. 13 ◽  
Author(s):  
Claire Stephane Metsopkeng ◽  
Chretien Lontsi Djimeli ◽  
Olive Vivien Noah Ewoti ◽  
Lucienne Marlyse Moungang ◽  
Paul Alain Nana ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Moringa Oleifera ◽  
Potable Water ◽  
Incubation Temperature ◽  
Enteropathogenic Escherichia Coli ◽  
Incubation Condition ◽  
E Coli ◽  
Extract Concentration ◽  
Cell Incubation ◽  
Potential Exploitation

This study aimed to evaluate in microcosm condition, the survival of Aeromonas hydrophila and Enteropathogenic Escherichia coli (EPEC), in the presence of M. oleifera aqueous seeds extract at concentrations varying from 1 to 40 g/L, and under 4 °C and 23 °C incubation temperature. It has been noted that cell abundances decrease gradually with the increasing in the seeds extract concentration. However, a marked cells regrowth was sometimes noted. In monospecies cell incubation condition, under 4 °C, the EPEC cells inhibition percentages (CIP) values varied from 52.12 to 99.84%. Those of A. hydrophila varied from 13.2 to 96%. The lowest CIPs were noted at the extract concentration 1g/L for EPEC and A. hydrophila. The highest CIP value was registered at 10 and 40 g/L for EPEC and at 15 g/L for A. hydrophila. Under 23 °C incubation, the EPEC CIPs values varied from 74.04 to 99.9% and those of A. hydrophila varied from 21.2 to 97.8%. For E. coli, the lowest and the highest CIP were recorded at the extract concentration 1g/L and 30 g/L, respectively. In bispecies cells incubation condition, the CIPs were relatively different. These results show the potential exploitation of M. oleifera extracts in the microbiological treatment of potable water.

Effect of Tannins on the In Vitro Growth of Escherichia coli O157:H7 and In Vivo Growth of Generic Escherichia coli Excreted from Steers

2007 ◽  
Vol 70 (3) ◽  
pp. 543-550 ◽  
Author(s):  
BYENG R. MIN ◽  
WILLIAM E. PINCHAK ◽  
ROBIN C. ANDERSON ◽  
TODD R. CALLAWAY
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Bacterial Growth ◽  
Escherichia Coli O157 ◽  
Tannin Extract ◽  
Bacterial Growth Rate ◽  
Linear Effect ◽  
E Coli

The effect of commercially available chestnut and mimosa tannins in vitro (experiment 1) or in vivo (experiment 2) on the growth or recovery of Escherichia coli O157:H7 or generic fecal E. coli was evaluated. In experiment 1, the mean growth rate of E. coli O157:H7, determined via the measurement of optical density at 600 nm during anaerobic culture in tryptic soy broth at 37°C, was reduced (P < 0.05) with as little as 400 μg of either tannin extract per ml of culture fluid. The addition of 200, 400, 600, 800, and 1,200 μg of tannins per ml significantly (P < 0.01) reduced the specific bacterial growth rate when compared with the nontannin control. The specific growth rate decreased with increasing dose levels up to 800 μg of tannins per ml. Bacterial growth inhibition effects in chestnut tannins were less pronounced than in mimosa tannins. Chestnut tannin extract addition ranged from 0 to 1,200 μg/ml, and a linear effect (P < 0.05) was observed in cultures incubated for 6 h against the recovery of viable cells, determined via the plating of each strain onto MacConkey agar, of E. coli O157:H7 strains 933 and 86-24, but not against strain 6058. Similar tests with mimosa tannin extract showed a linear effect (P < 0.05) against the recovery of E. coli O157:H7 strain 933 only. The bactericidal effect observed in cultures incubated for 24 h with the tannin preparations was similar, although it was less than that observed from cultures incubated for 6 h. When chestnut tannins (15 g of tannins per day) were infused intraruminally to steers fed a Bermuda grass hay diet in experiment 2, fecal E. coli shedding was lower on days 3 (P < 0.03), 12 (P = 0.08), and 15 (P < 0.001) when compared with animals that were fed a similar diet without tannin supplementation. It was concluded that dietary levels and sources of tannins potentially reduce the shedding of E. coli from the gastrointestinal tract.

Differentiation of Viable and Dead Escherichia coli O157:H7 Cells on and in Apple Structures and Tissues following Chlorine Treatment

2002 ◽  
Vol 65 (2) ◽  
pp. 251-259 ◽  
Author(s):  
SCOTT L. BURNETT ◽  
LARRY R. BEUCHAT
Keyword(s):  
Escherichia Coli ◽  
Live Cells ◽  
Confocal Scanning Laser Microscopy ◽  
Escherichia Coli O157 ◽  
Tissue Samples ◽  
E Coli ◽  
Sytox Green ◽  
Viable Cells ◽  
Nucleic Acid Stain ◽  
Protective Structures

Confocal scanning laser microscopy (CSLM) was used to differentiate viable and nonviable cells of Escherichia coli O157:H7 on and in raw apple tissues following treatment with water and 200 or 2,000 ppm active chlorine solution. Whole unwaxed Red Delicious cultivar apples at 25°C were inoculated by dipping in a suspension of E. coli O157:H7 (8.48 log10 CFU/ml) at 4°C, followed by treatment in water or chlorine solution at 21°C for 2 min. The dead cells on and in apples were distinguished from live cells by treating tissue samples with SYTOX green nucleic acid stain. Viable and dead cells were then labeled with an antibody conjugated with a fluorescent dye (Alexa Fluor 594). The percentage of viable cells on the apple surface, as well as at various depths in surface and internal structures, was determined. The mean percentages of viable cells located at the sites after treatment with water or chlorinated water were in the following order, which also reflects the order of protection against inactivation: floral tube wall (20.5%) > lenticels (15.0%) > damaged cuticle surrounding puncture wounds (13.0%) > intact cuticle (8.1%). The location of viable cells within tissues was dependent on the structure. Except for lenticels, the percentage of viable cells increased as depth into the CSLM stacks increased, indicating that cells attached to subsurface structures were better protected against inactivation with chlorine than were cells located on exposed surfaces. Further research is warranted to investigate the efficacy of other chemical sanitizers, as well as that of surfactants and solvents in combination with sanitizers, in removing or killing E. coli O157:H7 lodged in protective structures on the surface and within tissues of apples.

scholarly journals Susceptibility of Escherichia coli and Clostridium perfringens to sucrose monoesters of capric and lauric acid

2014 ◽  
Vol 59 (No. 8) ◽  
pp. 374-380
Author(s):  
E. Skřivanová ◽  
Š. Pražáková ◽  
O. Benada ◽  
P. Hovorková ◽  
MarounekM
Keyword(s):  
Escherichia Coli ◽  
Antibacterial Activity ◽  
Clostridium Perfringens ◽  
Lauric Acid ◽  
Cytoplasmic Membrane ◽  
E Coli ◽  
Enteropathogenic Bacteria ◽  
Viable Cells ◽  
Transmission Electron ◽  
Cytoplasmic Structures

The sucrose monoesters of capric and lauric acid were tested for their antibacterial activity towards two foodborne enteropathogenic bacteria &ndash; Escherichia coli (CCM 3954 &ndash; serotype O6 and E22 &ndash; serotype O103) and Clostridium perfringens (CNCTC 5459 and CIP 105178). Antibacterial activity was evaluated by the plating technique. Sucrose monocaprate significantly decreased the number of viable cells of E. coli at all tested concentrations (0.1&ndash;5 mg/ml). The overnight incubation of C. perfringens with the sucrose ester of lauric acid at 0.1&ndash;5 mg/ml reduced the number of viable cells below the detection limit (2 log<sub>10</sub> CFU/ml). Incubating E. coli CCM 3954 and C. perfringens CNCTC 5459 with monoesters (0.1 and 2 mg/ml) did not influence the K<sup>+</sup> permeability of the cytoplasmic membrane in cells during a 2.5-minute treatment. A 30-minute incubation of E. coli CCM 3954 and C. perfringens CNCTC 5459 with esters (0.1 and 2 mg/ml) revealed damage to cytoplasmic structures, as observed by transmission electron microscopy. &nbsp;

scholarly journals Rapid Growth of UropathogenicEscherichia coliduring Human Urinary Tract Infection

mBio ◽  
2018 ◽  
Vol 9 (2) ◽  
Author(s):  
Valerie S. Forsyth ◽  
Chelsie E. Armbruster ◽  
Sara N. Smith ◽  
Ali Pirani ◽  
A. Cody Springman ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Urinary Tract ◽  
Growth Rates ◽  
High Growth ◽  
Replication Forks ◽  
Chromosomal Replication ◽  
E Coli ◽  
Tract Infections

ABSTRACTUropathogenicEscherichia coli(UPEC) strains cause most uncomplicated urinary tract infections (UTIs). These strains are a subgroup of extraintestinal pathogenicE. coli(ExPEC) strains that infect extraintestinal sites, including urinary tract, meninges, bloodstream, lungs, and surgical sites. Here, we hypothesize that UPEC isolates adapt to and grow more rapidly within the urinary tract than otherE. coliisolates and survive in that niche. To date, there has not been a reliable method available to measure their growth ratein vivo. Here we used two methods: segregation of nonreplicating plasmid pGTR902, and peak-to-trough ratio (PTR), a sequencing-based method that enumerates bacterial chromosomal replication forks present during cell division. In the murine model of UTI, UPEC strain growth was robustin vivo, matching or exceedingin vitrogrowth rates and only slowing after reaching high CFU counts at 24 and 30 h postinoculation (hpi). In contrast, asymptomatic bacteriuria (ABU) strains tended to maintain high growth ratesin vivoat 6, 24, and 30 hpi, and population densities did not increase, suggesting that host responses or elimination limited population growth. Fecal strains displayed moderate growth rates at 6 hpi but did not survive to later times. By PTR,E. coliin urine of human patients with UTIs displayed extraordinarily rapid growth during active infection, with a mean doubling time of 22.4 min. Thus, in addition to traditional virulence determinants, including adhesins, toxins, iron acquisition, and motility, very high growth ratesin vivoand resistance to the innate immune response appear to be critical phenotypes of UPEC strains.IMPORTANCEUropathogenicEscherichia coli(UPEC) strains cause most urinary tract infections in otherwise healthy women. While we understand numerous virulence factors are utilized byE. colito colonize and persist within the urinary tract, these properties are inconsequential unless bacteria can divide rapidly and survive the host immune response. To determine the contribution of growth rate to successful colonization and persistence, we employed two methods: one involving the segregation of a nonreplicating plasmid in bacteria as they divide and the peak-to-trough ratio, a sequencing-based method that enumerates chromosomal replication forks present during cell division. We found that UPEC strains divide extraordinarily rapidly during human UTIs. These techniques will be broadly applicable to measurein vivogrowth rates of other bacterial pathogens during host colonization.

scholarly journals Fitness, Stress Resistance, and Extraintestinal Virulence in Escherichia coli

2013 ◽  
Vol 81 (8) ◽  
pp. 2733-2742 ◽  
Author(s):  
Alexandre Bleibtreu ◽  
Pierre-Alexis Gros ◽  
Cédric Laouénan ◽  
Olivier Clermont ◽  
Hervé Le Nagard ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Stress Response ◽  
Mouse Model ◽  
Stress Resistance ◽  
Maximum Growth ◽  
Competitive Fitness ◽  
Content Type ◽  
General Stress Response ◽  
E Coli

ABSTRACTThe extraintestinal virulence ofEscherichia coliis dependent on numerous virulence genes. However, there is growing evidence for a role of the metabolic properties and stress responses of strains in pathogenesis. We assessed the respective roles of these factors in strain virulence by developing phenotypic assays for measuringin vitroindividual and competitive fitness and the general stress response, which we applied to 82 commensal and extraintestinal pathogenicE. colistrains previously tested in a mouse model of sepsis. Individual fitness properties, in terms of maximum growth rates in various media (Luria-Bertani broth with and without iron chelator, minimal medium supplemented with gluconate, and human urine) and competitive fitness properties, estimated as the mean relative growth rate per generation in mixed cultures with a reference fluorescentE. colistrain, were highly diverse between strains. The activity of the main general stress response regulator, RpoS, as determined by iodine staining of the colonies, H2O2resistance, andrpoSsequencing, was also highly variable. No correlation between strain fitness and stress resistance and virulence in the mouse model was found, except that the maximum growth rate in urine was higher for virulent strains. Multivariate analysis showed that the number of virulence factors was the only independent factor explaining the virulence in mice. At the species level, growth capacity and stress resistance are heterogeneous properties that do not contribute significantly to the intrinsic virulence of the strains.

VARIATIONS IN THE CHARACTERISTICS OF E. COLI INDUCED BY QUATERNARY AMMONIUM COMPOUNDS

1951 ◽  
Vol 14 (4) ◽  
pp. 138-141 ◽  
Author(s):  
C. Kenneth Crocker
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Induced Resistance ◽  
Quaternary Ammonium ◽  
Quaternary Ammonium Compounds ◽  
Liquid Media ◽  
E Coli ◽  
Metallic Sheen ◽  
Small Colony ◽  
Ammonium Compounds

Escherichia coli lost the ability to produce gas in liquid media and formed atypical small colony variants on desoxycholate agar, concurrent with induced resistance to quaternary ammonium compounds. Paralleling high resistance, the metallic sheen of colonies on confirmatory medium did not appear. The variant strains showed a decrease in growth rate, failed to reduce methylene blue, and were unable to ferment normal sugars. Thus, with induced resistance, variations occurred in Escherechia coli such as to reduce the value of coliform tests used to identify its presence.

scholarly journals Cell Death in Escherichia coli dnaE(Ts) Mutants Incubated at a Nonpermissive Temperature Is Prevented by Mutation in the cydA Gene

2004 ◽  
Vol 186 (7) ◽  
pp. 2147-2155 ◽  
Author(s):  
Bernard Strauss ◽  
Kemba Kelly ◽  
Toros Dincman ◽  
Damian Ekiert ◽  
Theresa Biesieda ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Cell Death ◽  
Dna Synthesis ◽  
Dna Content ◽  
Electrophoretic Pattern ◽  
Luria Bertani ◽  
E Coli ◽  
Viable Cells ◽  
Rna And Protein Synthesis ◽  
Transformation Activity

ABSTRACT Cells of the Escherichia coli dnaE(Ts) dnaE74 and dnaE486 mutants die after 4 h of incubation at 40°C in Luria-Bertani medium. Cell death is preceded by elongation, is inhibited by chloramphenicol, tetracycline, or rifampin, and is dependent on cell density. Cells survive at 40°C when they are incubated at a high population density or at a low density in conditioned medium, but they die when the medium is supplemented with glucose and amino acids. Deletion of recA or sulA has no effect. We isolated suppressors which survived for long periods at 40°C but did not form colonies. The suppressors protected against hydroxyurea-induced killing. Sequence and complementation analysis indicated that suppression was due to mutation in the cydA gene. The DNA content of dnaE mutants increased about eightfold in 4 h at 40°C, as did the DNA content of the suppressed strains. The amount of plasmid pBR322 in a dnaE74 strain increased about fourfold, as measured on gels, and the electrophoretic pattern appeared to be normal even though the viability of the parent cells decreased 2 logs. Transformation activity also increased. 4′,6′-Diamidino-2-phenylindole staining demonstrated that there were nucleoids distributed throughout the dnaE filaments formed at 40°C, indicating that there was segregation of the newly formed DNA. We concluded that the DNA synthesized was physiologically competent, particularly since the number of viable cells of the suppressed strain increased during the first few hours of incubation. These observations support the view that E. coli senses the rate of DNA synthesis and inhibits septation when the rate of DNA synthesis falls below a critical level relative to the level of RNA and protein synthesis.

scholarly journals Titration and Conditional Knockdown of the prfB Gene in Escherichia coli: Effects on Growth and Overproduction of the Recombinant Mammalian Selenoprotein Thioredoxin Reductase

2006 ◽  
Vol 73 (2) ◽  
pp. 432-441 ◽  
Author(s):  
Olle Rengby ◽  
Elias S. J. Arnér
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Essential Gene ◽  
Thioredoxin Reductase ◽  
Lower Growth ◽  
E Coli ◽  
Native Promoter ◽  
Lower Growth Rate ◽  
The Cost ◽  
Translational Termination

ABSTRACT Release factor 2 (RF2), encoded by the prfB gene in Escherichia coli, catalyzes translational termination at UGA and UAA codons. Termination at UGA competes with selenocysteine (Sec) incorporation at Sec-dedicated UGA codons, and RF2 thereby counteracts expression of selenoproteins. prfB is an essential gene in E. coli and can therefore not be removed in order to increase yield of recombinant selenoproteins. We therefore constructed an E. coli strain with the endogenous chromosomal promoter of prfB replaced with the titratable PBAD promoter. Knockdown of prfB expression gave a bacteriostatic effect, while two- to sevenfold overexpression of RF2 resulted in a slightly lowered growth rate in late exponential phase. In a turbidostatic fermentor system the simultaneous impact of prfB knockdown on growth and recombinant selenoprotein expression was subsequently studied, using production of mammalian thioredoxin reductase as model system. This showed that lowering the levels of RF2 correlated directly with increasing Sec incorporation specificity, while also affecting total selenoprotein yield concomitant with a lower growth rate. This study thus demonstrates that expression of prfB can be titrated through targeted exchange of the native promoter with a PBAD-promoter and that knockdown of RF2 can result in almost full efficiency of Sec incorporation at the cost of lower total selenoprotein yield.

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