scholarly journals Persister cells mediate tolerance to metal oxyanions in Escherichia coli

Microbiology ◽  
2005 ◽  
Vol 151 (10) ◽  
pp. 3181-3195 ◽  
Author(s):  
Joe J. Harrison ◽  
Howard Ceri ◽  
Nicole J. Roper ◽  
Erin A. Badry ◽  
Kimberley M. Sproule ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Viable Cell ◽  
Small Population ◽  
Water Soluble ◽  
Bacterial Cells ◽  
Persister Cells ◽  
Term Survival ◽  
E Coli ◽  
Cell Counts ◽  
High Concentrations

Bacterial cultures produce subpopulations of cells termed ‘persisters’, reputedly known for high tolerance to killing by antibiotics. Ecologically, antibiotics produced by competing microflora are only one potential stress encountered by bacteria. Another pressure in the environment is toxic metals that are distributed ubiquitously by human pollution, volcanic activity and the weathering of minerals. This study evaluated the time- and concentration-dependent killing of Escherichia coli planktonic and biofilm cultures by the water-soluble metal(loid) oxyanions chromate (), arsenate (), arsenite (), selenite (), tellurate () and tellurite (). Correlative to previous reports in the literature, control antibiotic assays indicated that a small proportion of E. coli biofilm populations remained recalcitrant to killing by antibiotics (even with 24 h exposure). In contrast, metal oxyanions presented a slow, bactericidal action that eradicated biofilms. When exposed for 2 h, biofilms were up to 310 times more tolerant to killing by metal oxyanions than corresponding planktonic cultures. However, by 24 h, planktonic cells and biofilms were eradicated at approximately the same concentration in all instances. Coloured complexes of metals and chelators could not be generated in biofilms exposed to or , suggesting that the extracellular polymeric matrix of E. coli may have a low binding affinity for metal oxyanions. Viable cell counts at 2 and 24 h exposure revealed that, at high concentrations, all of the metal oxyanions had killed 99 % (or a greater proportion) of the bacterial cells in biofilm populations. It is suggested here that the short-term survival of <1 % of the bacterial population corresponds well with the hypothesis that a small population of persister cells may be responsible for the time-dependent tolerance of E. coli biofilms to high concentrations of metal oxyanions.

scholarly journals A Role for Single-Stranded Exonucleases in the Use of DNA as a Nutrient

2009 ◽  
Vol 191 (11) ◽  
pp. 3712-3716 ◽  
Author(s):  
Vyacheslav Palchevskiy ◽  
Steven E. Finkel
Keyword(s):  
Escherichia Coli ◽  
Bacterial Cells ◽  
Wild Type ◽  
Nutrient Source ◽  
Term Survival ◽  
Natural Competence ◽  
E Coli ◽  
Double Stranded Dna ◽  
Better Than

ABSTRACT Nutritional competence is the ability of bacterial cells to utilize exogenous double-stranded DNA molecules as a nutrient source. We previously identified several genes in Escherichia coli that are important for this process and proposed a model, based on models of natural competence and transformation in bacteria, where it is assumed that single-stranded DNA (ssDNA) is degraded following entry into the cytoplasm. Since E. coli has several exonucleases, we determined whether they play a role in the long-term survival and the catabolism of DNA as a nutrient. We show here that mutants lacking either ExoI, ExoVII, ExoX, or RecJ are viable during all phases of the bacterial life cycle yet cannot compete with wild-type cells during long-term stationary-phase incubation. We also show that nuclease mutants, alone or in combination, are defective in DNA catabolism, with the exception of the ExoX− single mutant. The ExoX− mutant consumes double-stranded DNA better than wild-type cells, possibly implying the presence of two pathways in E. coli for the processing of ssDNA as it enters the cytoplasm.

Antibacterial Effect of Water-Soluble Arrowroot (Puerariae radix) Tea Extracts on Foodborne Pathogens in Ground Beef and Mushroom Soup

2004 ◽  
Vol 67 (9) ◽  
pp. 1953-1956 ◽  
Author(s):  
S. KIM ◽  
D. Y. C. FUNG
Keyword(s):  
Foodborne Pathogens ◽  
Salmonella Enteritidis ◽  
Ground Beef ◽  
Viable Cell ◽  
Water Soluble ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Cell Counts ◽  
Tea Extract ◽  
And Staphylococcus Aureus

Antimicrobial activity of water-soluble arrowroot tea extract was evaluated against Escherichia coli O157:H7, Salmonella enterica Serotype Enteritidis, Listeria monocytogenes, and Staphylococcus aureus in ground beef and mushroom soup. The concentrations of arrowroot tea used were 0, 3, and 6% (wt/wt) for ground beef and 0, 1, 5, and 10% (wt/vol) for mushroom soup. Samples without tea extract were considered controls. Each sample was stored for 0, 1, 3, 5, and 7 days at 7°C for ground beef and for 0, 1, 3, and 5 days at 35°C for mushroom soup. On each sampling time, proper dilutions were spread plated on each pathogen-specific agar. Viable cell counts of each pathogen were performed after incubation at 35°C for 24 to 48 h. For ground beef, Salmonella Enteritidis and L. monocytogenes were slightly suppressed by approximately 1.5 log, compared with the control, on day 7 at 3 and 6% arrowroot tea treatment. For mushroom soup, all test pathogens were suppressed by 6.5, 4.7, 3.4, and 4.3 log at 5% and 6.0, 4.7, 5.0, and 4.3 log at 10% against E. coli O157:H7, Salmonella Enteritidis, L. monocytogenes, and S. aureus, respectively, compared with the control on day 5. Mushroom soup with 1% arrowroot tea also showed 2.3- and 2.7-log growth suppression of Salmonella Enteritidis and S. aureus, respectively, compared with the control on day 5. This study showed that the use of arrowroot tea would effectively inhibit the microbial growth of both gram-negative and gram-positive foodborne pathogens in various foods, especially liquid foods.

Isolation and Purification of Colicin ECL 12, a Bacteriocin That Inhibits Strains of Escherichia coli O157:H7†

1997 ◽  
Vol 60 (12) ◽  
pp. 1520-1528 ◽  
Author(s):  
WANDA J. LYON ◽  
DENNIS G. OLSON
Keyword(s):  
Escherichia Coli ◽  
Proteolytic Enzymes ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Viable Cell ◽  
Exchange Chromatography ◽  
Isolation And Purification ◽  
E Coli ◽  
Log Reduction ◽  
Cell Counts

A swine fecal isolate, identified as Escherichia coli ECL12, was found to produce an antimicrobial substance designated as colicin ECL12. Colicin ECL12 was inhibitory against 20 strains of E. coli O157:H7 previously isolated from both human and bovine feces. Identification of the producer strain was determined phenotypically by biochemical and morphological tests. Colicin ECL12 was sensitive to several proteolytic enzymes. Adsorption of colicin ECL12 to sensitive cells of E. coli O157:H7 was bactericidal, resulting in a 2 log reduction in viable cell counts. Colicin ECL12 was purified from strain ECL12 by cell extraction and ion-exchange chromatography. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of colicin ECL12 resolved a single protein with a molecular weight of approximately 65,000.

Antimicrobial Performance of Alkaline Ionic Fluid (GC-100X) and Its Ability To Remove Escherichia coli O157:H7 from the Surface of Tomatoes

2003 ◽  
Vol 66 (9) ◽  
pp. 1604-1610 ◽  
Author(s):  
N. H. KWON ◽  
S. H. KIM ◽  
J. Y. KIM ◽  
J. Y. LIM ◽  
J. M. KIM ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Foodborne Pathogens ◽  
Hard Water ◽  
Viable Cell ◽  
Organic Load ◽  
Korean Isolate ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Cell Counts ◽  
Chlorine Water

An efficacy test of GC-100X, a noncorrosive alkaline ionic fluid (pH 12) composed of free radicals and supplemented with xylitol, was carried out against six major foodborne pathogens—Staphylococcus aureus FRI 913, Salmonella enterica serovar Enteritidis ATCC 13076, S. enterica serovar Typhimurium DT104 Korean isolate, Vibrio parahaemolyticus ATCC 17803, Escherichia coli O157:H7 ATCC 43894, and Pseudomonas aeruginosa KCTC 1637—at three different temperatures (4, 25, and 36°C) with or without organic load (2% yeast extract). Results revealed a more than 4-log10 (CFU/ml) reduction (1.0 × 104 CFU/ml reduction) against all pathogens reacted at 37°C for 3 h in the absence of organic material. GC-100X solution diluted with an equal volume of distilled or standard hard water (300 ppm CaCO3) showed effective bactericidal activity, particularly against gram-negative bacteria. Washing efficacy of GC-100X solution was compared against E. coli O157:H7 on cherry tomato surfaces with those of a commercially used detergent and chlorine water (100 ppm). Viable cell counts of E. coli O157:H7 that had penetrated to the cores of tomatoes after sanitizing treatment revealed that GC-100X stock and its 5% diluted solutions had similar washing effects to 100-ppm chlorine water and were more effective than the other kitchen detergent. These results indicate that GC-100X has good bactericidal and sanitizing activities and is useful as a new sanitizer for food safety and kitchen hygiene.

Combined Effect of Water Activity and pH on the Inhibition of Escherichia coli by Nisin

2001 ◽  
Vol 64 (10) ◽  
pp. 1510-1514 ◽  
Author(s):  
PATRICIA CERRUTTI ◽  
MAURICIO R. TEREBIZNIK ◽  
MARTA SEGOVIA de HUERGO ◽  
ROSA JAGUS ◽  
ANA M. R. PILOSOF
Keyword(s):  
Escherichia Coli ◽  
Water Activity ◽  
Viable Cell ◽  
Stress Factors ◽  
Doehlert Design ◽  
Survival Fraction ◽  
E Coli ◽  
Cell Counts ◽  
Maximum Inhibition ◽  
Influence Of Ph

The Doehlert design and surface response methodology were used to study the influence of pH and water activity (aw) on Escherichia coli inhibition by nisin. Combining stress factors at levels where they are not inhibitory by themselves, a reduction of E. coli survival fraction can be achieved with lower nisin doses than in a single nisin treatment. For all the pH values assayed, a synergistic effect of aw and nisin concentration was detected, and the isoresponse lines showed the existence of an area of maximum inhibition. Factors that reduced viable cell counts by 4 to 5 log cycles were 1,000 to 1,400 IU of nisin per ml at pH 5.5 to 6.5 and a water activity of 0.97 and 0.98. The addition of different ionic and nonionic solutes to control aw suggested that the effect of aw in the inhibitory action of nisin on E. coli cells was not solute-specific. The use of the Doehlert experimental design was effective to determine the optimal combination of stress factors, as well as to point out the most important variables that affected E. coli inhibition.

scholarly journals Persister Cells Resuscitate via Ribosome Modification by 23S rRNA Pseudouridine Synthase RluD

2019 ◽  
Author(s):  
Sooyeon Song ◽  
Thomas K. Wood
Keyword(s):  
Escherichia Coli ◽  
Small Rna ◽  
23S Rrna ◽  
Bacterial Cells ◽  
Persister Cells ◽  
E Coli ◽  
Pseudouridine Synthase ◽  
Dormant Cells ◽  
Wide Range ◽  
Persister Cell

ABSTRACTUpon a wide range of stress conditions (e.g., nutrient, antibiotic, oxidative), a subpopulation of bacterial cells known as persisters survive by halting metabolism. These cells resuscitate rapidly to reconstitute infections once the stress is removed and nutrients are provided. However, how these dormant cells resuscitate is not understood well but involves reactivating ribosomes. By screening 10,000 compounds directly for stimulating Escherichia coli persister cell resuscitation, we identified that 2-{[2-(4-bromophenyl)-2-oxoethyl]thio}-3-ethyl-5,6,7,8-tetrahydro[1]benzothieno[2,3-d]pyrimidin-4(3H)-one (BPOET) stimulates resuscitation. Critically, by screening 4,267 E. coli proteins, we determined that BPOET activates hibernating ribosomes via 23S rRNA pseudouridine synthase RluD, which increases ribosome activity. Corroborating the increased waking with RluD, production of RluD increased the number of active ribosomes in persister cells. Also, inactivating the small RNA RybB which represses rluD led to faster persister resuscitation. Hence, persister cells resuscitate via activation of RluD.

Minimum and Maximum Temperatures for Growth and Verotoxin Production by Hemorrhagic Strains of Escherichia coli

1995 ◽  
Vol 58 (4) ◽  
pp. 352-356 ◽  
Author(s):  
SAMUEL A. PALUMBO ◽  
JEFFREY E. CALL ◽  
FRANKIE J. SCHULTZ ◽  
AARON C. WILLIAMS
Keyword(s):  
Escherichia Coli ◽  
Brain Heart Infusion ◽  
Viable Cell ◽  
Toxin Production ◽  
Viable Count ◽  
Influence Of Temperature ◽  
E Coli ◽  
Cell Counts ◽  
Influence Of Temperature On ◽  
Maximum Temperatures

The influence of temperature on growth and verotoxin production by Escherichia coli strains was studied in brain heart infusion (BHI) broth both in shake cultures at various temperatures and in a temperature-gradient incubator. All strains of E. coli surveyed grew from at least 10 to 45°C, with some strains growing at 8° C. Verotoxin production (determined using the Vero cell–assay system) was a function of both temperature and time, with the highest titers produced at temperatures supporting the fastest growth (based on days to visible turbidity) and highest viable cell counts. However, for strains producing verotoxin, toxin production was detected at any temperature supporting growth. Three strains (of 16 tested) increased 1000-fold in viable count in 4 to 6 days at 10°C. The data presented here indicate that most E. coli strains surveyed can easily grow at ca. 10°C and thus suggest the potential for growth in temperature-abused refrigerated foods.

scholarly journals An Assessment of the Viability of Lytic Phages and Their Potency against Multidrug Resistant Escherichia coli O177 Strains under Simulated Rumen Fermentation Conditions

Antibiotics ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 265
Author(s):  
Peter Kotsoana Montso ◽  
Caven Mguvane Mnisi ◽  
Collins Njie Ateba ◽  
Victor Mlambo
Keyword(s):  
Escherichia Coli ◽  
Rumen Fluid ◽  
Multidrug Resistant ◽  
Rumen Fermentation ◽  
Ruminal Fermentation ◽  
Fermentation Conditions ◽  
E Coli ◽  
Cell Counts ◽  
Milk Contamination ◽  
Novel Strategy

Preslaughter starvation and subacute ruminal acidosis in cattle are known to promote ruminal proliferation of atypical enteropathogenic Escherichia coli strains, thereby increasing the risk of meat and milk contamination. Using bacteriophages (henceforth called phages) to control these strains in the rumen is a potentially novel strategy. Therefore, this study evaluated the viability of phages and their efficacy in reducing E. coli O177 cells in a simulated ruminal fermentation system. Fourteen phage treatments were allocated to anaerobic serum bottles containing a grass hay substrate, buffered (pH 6.6–6.8) bovine rumen fluid, and E. coli O177 cells. The serum bottles were then incubated at 39 °C for 48 h. Phage titres quadratically increased with incubation time. Phage-induced reduction of E. coli O177 cell counts reached maximum values of 61.02–62.74% and 62.35–66.92% for single phages and phage cocktails, respectively. The highest E. coli O177 cell count reduction occurred in samples treated with vB_EcoM_366B (62.31%), vB_EcoM_3A1 (62.74%), vB_EcoMC3 (66.67%), vB_EcoMC4 (66.92%), and vB_EcoMC6 (66.42%) phages. In conclusion, lytic phages effectively reduced E. coli O177 cells under artificial rumen fermentation conditions, thus could be used as a biocontrol strategy in live cattle to reduce meat and milk contamination in abattoirs and milking parlours, respectively.

High Pressure Inactivation of Escherichia coli, Campylobacter jejuni, and Spoilage Microbiota on Poultry Meat

2012 ◽  
Vol 75 (3) ◽  
pp. 497-503 ◽  
Author(s):  
YANG LIU ◽  
MIRKO BETTI ◽  
MICHAEL G. GÄNZLE
Keyword(s):  
Escherichia Coli ◽  
High Pressure ◽  
Campylobacter Jejuni ◽  
Resistant Mutant ◽  
Poultry Meat ◽  
E Coli ◽  
Cell Counts ◽  
Meat Spoilage ◽  
Brochothrix Thermosphacta ◽  
Pressure Resistance

This study evaluated the high pressure inactivation of Campylobacter jejuni, Escherichia coli, and poultry meat spoilage organisms. All treatments were performed in aseptically prepared minced poultry meat. Treatment of 19 strains of C. jejuni at 300 MPa and 30°C revealed a large variation of pressure resistance. The recovery of pressure-induced sublethally injured C. jejuni depended on the availability of iron. The addition of iron content to enumeration media was required for resuscitation of sublethally injured cells. Survival of C. jejuni during storage of refrigerated poultry meat was analyzed in fresh and pressure-treated poultry meat, and in the presence or absence of spoilage microbiota. The presence of spoilage microbiota did not significantly influence the survival of C. jejuni. Pressure treatment at 400 MPa and 40°C reduced cell counts of Brochothrix thermosphacta, Carnobacterium divergens, C. jejuni, and Pseudomonas fluorescens to levels below the detection limit. Cell counts of E. coli AW1.7, however, were reduced by only 3.5 log (CFU/g) and remained stable during subsequent refrigerated storage. The resistance to treatment at 600 MPa and 40°Cof E. coli AW1.7 was compared with Salmonella enterica, Shiga toxin–producing E. coli and nonpathogenic E. coli strains, and Staphylococcus spp. Cell counts of all organisms except E. coli AW 1.7 were reduced by more than 6 log CFU/g. Cell counts of E. coli AW1.7 were reduced by 4.5 log CFU/g only. Moreover, the ability of E. coli AW1.7 to resist pressure was comparable to the pressure-resistant mutant E. coli LMM1030. Our results indicate that preservation of fresh meat requires a combination of high pressure with high temperature (40 to 60°C) or other antimicrobial hurdles.

scholarly journals The dynamic balance of import and export of zinc in Escherichia coli suggests a heterogeneous population response to stress

2015 ◽  
Vol 12 (106) ◽  
pp. 20150069 ◽  
Author(s):  
Hiroki Takahashi ◽  
Taku Oshima ◽  
Jon L. Hobman ◽  
Neil Doherty ◽  
Selina R. Clayton ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Zinc Concentration ◽  
Systems Approach ◽  
Model Simulation ◽  
Dynamic Balance ◽  
Model Fitting ◽  
Viable Cell ◽  
Population Heterogeneity ◽  
Cell Counts ◽  
Import And Export

Zinc is essential for life, but toxic in excess. Thus all cells must control their internal zinc concentration. We used a systems approach, alternating rounds of experiments and models, to further elucidate the zinc control systems in Escherichia coli . We measured the response to zinc of the main specific zinc import and export systems in the wild-type, and a series of deletion mutant strains. We interpreted these data with a detailed mathematical model and Bayesian model fitting routines. There are three key findings: first, that alternate, non-inducible importers and exporters are important. Second, that an internal zinc reservoir is essential for maintaining the internal zinc concentration. Third, our data fitting led us to propose that the cells mount a heterogeneous response to zinc: some respond effectively, while others die or stop growing. In a further round of experiments, we demonstrated lower viable cell counts in the mutant strain tested exposed to excess zinc, consistent with this hypothesis. A stochastic model simulation demonstrated considerable fluctuations in the cellular levels of the ZntA exporter protein, reinforcing this proposal. We hypothesize that maintaining population heterogeneity could be a bet-hedging response allowing a population of cells to survive in varied and fluctuating environments.

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