Inactivation of Escherichia Coli on Titanium Dioxide Photocatalysis Nanoparticles

2010 ◽  
Vol 96 ◽  
pp. 99-104 ◽  
Author(s):  
Jing Wang ◽  
Zhi Jiang Ji ◽  
Zhong He Shui ◽  
Xiao Yan Wang ◽  
Nan Ding ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Titanium Dioxide ◽  
Cell Membrane ◽  
Particle Diameter ◽  
Average Diameter ◽  
Nano Tio2 ◽  
E Coli ◽  
Tio2 Particles ◽  
Titanium Dioxide Photocatalysis ◽  
The Difference

The effects of P25 TiO2 made by DEGUSSA and one kind nano-titanium dioxide made by a certain company in China (Expressed by Tc) on Escherichia coli were tested by the minimal inhibitory concentration (MIC) method, and the status dispersed of two kinds nano-TiO2 and the micro-phenomenon of the effect on Escherichia coli were observed by scanning electron microscope (SEM). The hydroxyl radical (•OH) signal intensity in liquid produced by nano-TiO2 was tested by electron spinning resonance (ESR). It was found that the MIC of the P25 and Tc were 500 mg/L and 5 g/L, respectively. The cells of E. coli which were attached by the nano-TiO2 particles were damaged strongly, and the membrane was dissolved and dispersed under SEM. The intensity of •OH signal produced by P25 was stronger than that of Tc tested by ESR. The size of E. coli was 0.4~0.7×1~3 µm, and the average diameter of nano-TiO2 was 20 nm. When the nano-TiO2 particles touch the E. coli, it would stick to the surface of the cell wall and destroy the cell membrane, lead to the canker of cell membrane and the outflow of cytoplasm. The difference of the MIC between the two kinds of nano-powders may be due to their dispersion degree and the particle diameter which influence the •OH production.

scholarly journals Influence of Cationic meso-Substituted Porphyrins on the Antimicrobial Photodynamic Efficacy and Cell Membrane Interaction in Escherichia coli

2019 ◽  
Vol 20 (1) ◽  
pp. 134 ◽  
Author(s):  
Alexandra N. Hurst ◽  
Beth Scarbrough ◽  
Roa Saleh ◽  
Jessica Hovey ◽  
Farideh Ari ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Cell Membrane ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Cationic Porphyrins ◽  
Cationic Porphyrin ◽  
E Coli ◽  
Live Cell Microscopy ◽  
The Difference ◽  
The Hill

Photodynamic inactivation (PDI) is a non-antibiotic option for the treatment of infectious diseases. Although Gram-positive bacteria have been shown to be highly susceptible to PDI, the inactivation of Gram-negative bacteria has been more challenging due to the impermeability properties of the outer membrane. In the present study, a series of photosensitizers which contain one to four positive charges (1–4) were used to evaluate the charge influence on the PDI of a Gram-negative bacteria, Escherichia coli (E. coli), and their interaction with the cell membrane. The dose-response PDI results confirm the relevance of the number of positive charges on the porphyrin molecule in the PDI of E. coli. The difference between the Hill coefficients of cationic porphyrins with 1–3 positive charges and the tetra-cationic porphyrin (4) revealed potential variations in their mechanism of inactivation. Fluorescent live-cell microscopy studies showed that cationic porphyrins with 1–3 positive charges bind to the cell membrane of E. coli, but are not internalized. On the contrary, the tetra-cationic porphyrin (4) permeates through the membrane of the cells. The contrast in the interaction of cationic porphyrins with E. coli confirmed that they followed different mechanisms of inactivation. This work helps to have a better understanding of the structure-activity relationship in the efficiency of the PDI process of cationic porphyrins against Gram-negative bacteria.

scholarly journals Modification by an R determinant for streptomycin of hissd phenotype in a mutant strain of Escherichia coli B

1968 ◽  
Vol 12 (2) ◽  
pp. 109-116 ◽  
Author(s):  
A. M. Molina ◽  
L. Calegari ◽  
G. Conte
Keyword(s):  
Escherichia Coli ◽  
Cell Membrane ◽  
Mutant Strain ◽  
Minimal Medium ◽  
Specific Requirement ◽  
Resistance Level ◽  
E Coli ◽  
Level Characteristic ◽  
Escherichia Coli B

When an R determinant for streptomycin is transferred into a conditionally streptomycin-dependent E. coli B mutant—which requires in minimal medium either histidine or streptomycin—the latter behaves like a histidineless strain. This phenotype modification shows that the repairing action of streptomycin is prevented. The specific requirement of the strain is not now replaced even by streptomycin concentrations up to 10000 µg/ml at which the conditionally streptomycin-dependent mutant could originally grow, and which are well beyond the resistance level characteristic of the R determinant itself. These data seem to suggest that a reduction in permeability of the cell membrane cannot be held responsible for the phenomenon observed.

scholarly journals Proteorhodopsin Overproduction Enhances the Long-Term Viability of Escherichia coli

2019 ◽  
Vol 86 (1) ◽  
Author(s):  
Yizhi Song ◽  
Michaël L. Cartron ◽  
Philip J. Jackson ◽  
Paul A. Davison ◽  
Mark J. Dickman ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Raman Spectroscopy ◽  
Cell Membrane ◽  
Single Cell ◽  
Marine Bacteria ◽  
Membrane Area ◽  
Content Type ◽  
E Coli ◽  
Wide Range

ABSTRACT Genes encoding the photoreactive protein proteorhodopsin (PR) have been found in a wide range of marine bacterial species, reflecting the significant contribution that PR makes to energy flux and carbon cycling in ocean ecosystems. PR can also confer advantages to enhance the ability of marine bacteria to survive periods of starvation. Here, we investigate the effect of heterologously produced PR on the viability of Escherichia coli. Quantitative mass spectrometry shows that E. coli, exogenously supplied with the retinal cofactor, assembles as many as 187,000 holo-PR molecules per cell, accounting for approximately 47% of the membrane area; even cells with no retinal synthesize ∼148,000 apo-PR molecules per cell. We show that populations of E. coli cells containing PR exhibit significantly extended viability over many weeks, and we use single-cell Raman spectroscopy (SCRS) to detect holo-PR in 9-month-old cells. SCRS shows that such cells, even incubated in the dark and therefore with inactive PR, maintain cellular levels of DNA and RNA and avoid deterioration of the cytoplasmic membrane, a likely basis for extended viability. The substantial proportion of the E. coli membrane required to accommodate high levels of PR likely fosters extensive intermolecular contacts, suggested to physically stabilize the cell membrane and impart a long-term benefit manifested as extended viability in the dark. We propose that marine bacteria could benefit similarly from a high PR content, with a stabilized cell membrane extending survival when those bacteria experience periods of severe nutrient or light limitation in the oceans. IMPORTANCE Proteorhodopsin (PR) is part of a diverse, abundant, and widespread superfamily of photoreactive proteins, the microbial rhodopsins. PR, a light-driven proton pump, enhances the ability of the marine bacterium Vibrio strain AND4 to survive and recover from periods of starvation, and heterologously produced PR extends the viability of nutrient-limited Shewanella oneidensis. We show that heterologously produced PR enhances the viability of E. coli cultures over long periods of several weeks and use single-cell Raman spectroscopy (SCRS) to detect PR in 9-month-old cells. We identify a densely packed and consequently stabilized cell membrane as the likely basis for extended viability. Similar considerations are suggested to apply to marine bacteria, for which high PR levels represent a significant investment in scarce metabolic resources. PR-stabilized cell membranes in marine bacteria are proposed to keep a population viable during extended periods of light or nutrient limitation, until conditions improve.

scholarly journals Persistence of Escherichia coli O157:H12 and Escherichia coli K12 as Non-pathogenic Surrogates for O157:H7 on Lettuce Cultivars Irrigated With Secondary-Treated Wastewater and Roof-Collected Rain Water in the Field

2020 ◽  
Vol 4 ◽  
Author(s):  
Hsin-Bai Yin ◽  
Nidhi Gupta ◽  
Chi-Hung Chen ◽  
Ashley Boomer ◽  
Abani Pradhan ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Pathogenic Bacteria ◽  
Water Source ◽  
Water Sources ◽  
Rain Water ◽  
Treated Wastewater ◽  
E Coli ◽  
Water Characteristics ◽  
The Difference ◽  
Alternative Water

Treated wastewater (TW) and roof-collected rain water (RW) that meet the required microbial quality as per Food Safety Modernization Act (FSMA) regulation may serve as alternative irrigation water sources to decrease the pressure on the current water scarcity. Alternative water sources may have different water characteristics that influence the survival and transfer of microorganisms to the irrigated produce. Further, these water sources may contain pathogenic bacteria such as Shiga-toxigenic Escherichia coli. To evaluate the risk associated with TW and RW irrigation on the fresh produce safety, the effect of TW and RW irrigation on the transfer of two non-pathogenic E. coli strains as surrogates for E. coli O157:H7 to different lettuce cultivars grown in the field was investigated. Lettuce cultivars “Annapolis,” “Celinet,” and “Coastline” were grown in the field at the Fulton farm (Chambersburg, PA). Approximately 10 days before harvest, lettuce plants were spray-irrigated with groundwater (GW), TW, or RW containing 6 log CFU ml−1 of a mixture of nalidixic acid-resistant E. coli O157:H12 and chloramphenicol-resistant E. coli K12 in fecal slurry as non-pathogenic surrogates for E. coli O157:H7. On 0, 1, 3, 7, and 10 days post-irrigation, four replicate lettuce leaf samples (30 g per sample) from each group were collected and pummeled in 120 ml of buffered peptone water for 2 min, followed by spiral plating on MacConkey agars with antibiotics. Results showed that the recovery of E. coli O157:H12 was significantly greater than the populations of E. coli K12 recovered from the irrigated lettuce regardless of the water sources and the lettuce cultivars. The TW irrigation resulted in the lowest recovery of the E. coli surrogates on the lettuce compared to the populations of these bacteria recovered from the lettuce with RW and GW irrigation on day 0. The difference in leaf characteristics of lettuce cultivars significantly influenced the recovery of these surrogates on lettuce leaves. Populations of E. coli O157:H12 recovered from the RW-irrigated “Annapolis” lettuce were significantly lower than the recovery of this bacterium from the “Celinet” and “Coastline” lettuce (P < 0.05). Overall, the recovery of specific E. coli surrogates from the RW and TW irrigated lettuce was comparable to the lettuce with the GW irrigation, where GW served as a baseline water source. E. coli O157:H12 could be a more suitable surrogate compared to E. coli K12 because it is an environmental watershed isolate. The findings of this study provide critical information in risk assessment evaluation of RW and TW irrigation on lettuce in Mid-Atlantic area.

In Vitro Antibacterial Activity and Mechanism of Monocaprylin against Escherichia coli and Staphylococcus aureus

2018 ◽  
Vol 81 (12) ◽  
pp. 1988-1996 ◽  
Author(s):  
JIANYU WANG ◽  
MAOMAO MA ◽  
JUN YANG ◽  
LONG CHEN ◽  
PING YU ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Antibacterial Activity ◽  
Membrane Potential ◽  
Cell Membrane ◽  
Sodium Benzoate ◽  
Rapid Change ◽  
Potassium Sorbate ◽  
E Coli

ABSTRACT In the present study, the antibacterial activity of monocaprylin in comparison with sodium benzoate and potassium sorbate against Staphylococcus aureus and Escherichia coli was assessed by measuring MIC, MBC, effect of pH on MIC, and incubation temperature on bactericidal efficacy. Results showed that monocaprylin exhibited an excellent antibacterial activity against both strains, with the lowest MIC and MBC of 1.28 mg/mL. A MIC of monocaprylin remained unchanged despite the pH values of culture medium, ranging from 5 to 9, unlike that of potassium sorbate or sodium benzoate. Furthermore, monocaprylin at MBC effectively reduced the population of E. coli and S. aureus by >5.5 log CFU/mL at 25°C within 6 h and decreased E. coli by approximately 5.0 log CFU/mL and S. aureus by 2.9 log CFU/mL at 12 h. The underlying mechanism of monocaprylin was then investigated by measuring β-galactosidase activity, membrane potential, release of cellular contents, scanning electron microscopy, and transmission electron microscopy observations. Results indicated that monocaprylin killed E. coli by the rapid change in permeability and integrity of cell membrane, leading to decline of membrane potential, leakage of nucleic acids and proteins, and ultimately cell membrane disintegration and lysis. On the other hand, monocaprylin might exert its antibacterial activity against S. aureus mainly by diffusing across the cell wall, collapsing the cell membrane, and disturbing the order of intracellular contents. These findings indicated that monocaprylin had better antibacterial ability compared with traditional synthetic preservatives and might be a potential antibacterial additive independent of pH.

scholarly journals Uropathogenic Escherichia coli Biofilm-Forming Capabilities are not Predictable from Clinical Details or from Colonial Morphology

Diseases ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 11 ◽  
Author(s):  
Shane Whelan ◽  
Mary Claire O’Grady ◽  
Dan Corcoran ◽  
Karen Finn ◽  
Brigid Lucey
Keyword(s):  
Escherichia Coli ◽  
Biofilm Formation ◽  
Culture Medium ◽  
Recurrent Infection ◽  
Positive Control ◽  
Uropathogenic Escherichia Coli ◽  
E Coli ◽  
Recurrent Uti ◽  
Colonial Morphology ◽  
The Difference

Antibiotic resistance is increasing to an extent where efficacy is not guaranteed when treating infection. Biofilm formation has been shown to complicate treatment, whereby the formation of biofilm is associated with higher minimum inhibitory concentration values of antibiotic. The objective of the current paper was to determine whether biofilm formation is variable among uropathogenic Escherichia coli isolates and whether formation is associated with recurrent urinary tract infection (UTI), and whether it can be predicted by phenotypic appearance on culture medium A total of 62 E. coli isolates that were reported as the causative agent of UTI were studied (33 from patients denoted as having recurrent UTI and 29 from patients not specified as having recurrent UTI). The biofilm forming capability was determined using a standard microtitre plate method, using E. coli ATCC 25922 as the positive control. The majority of isolates (93.6%) were found to be biofilm formers, whereby 81% were denoted as strong or very strong producers of biofilm when compared to the positive control. Through the use of a Wilcox test, the difference in biofilm forming propensity between the two patient populations was found to not be statistically significant (p = 0.5). Furthermore, it was noted that colony morphology was not a reliable predictor of biofilm-forming propensity. The findings of this study indicate that biofilm formation is very common among uropathogens, and they suggest that the biofilm-forming capability might be considered when treating UTI. Clinical details indicating a recurrent infection were not predictors of biofilm formation.

scholarly journals Uropathogenic Escherichia coli Triggers Oxygen-Dependent Apoptosis in Human Neutrophils through the Cooperative Effect of Type 1 Fimbriae and Lipopolysaccharide

2004 ◽  
Vol 72 (8) ◽  
pp. 4570-4578 ◽  
Author(s):  
Robert Blomgran ◽  
Limin Zheng ◽  
Olle Stendahl
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract ◽  
Human Neutrophils ◽  
Dependent Manner ◽  
E Coli ◽  
Type 1 Fimbriae ◽  
The Difference ◽  
Tract Infections ◽  
Neutrophil Survival

ABSTRACT Type 1 fimbriae are the most commonly expressed virulence factor on uropathogenic Escherichia coli. In addition to promoting avid bacterial adherence to the uroepithelium and enabling colonization, type 1 fimbriae recruit neutrophils to the urinary tract as an early inflammatory response. Using clinical isolates of type 1 fimbriated E. coli and an isogenic type 1 fimbria-negative mutant (CN1016) lacking the FimH adhesin, we investigated if these strains could modulate apoptosis in human neutrophils. We found that E. coli expressing type 1 fimbriae interacted with neutrophils in a mannose- and lipopolysaccharide (LPS)-dependent manner, leading to apoptosis which was triggered by the intracellular generation of reactive oxygen species. This induced neutrophil apoptosis was abolished by blocking FimH-mediated attachment, by inhibiting NADPH oxidase activation, or by neutralizing LPS. In contrast, CN1016, which did not adhere to or activate the respiratory burst of neutrophils, delayed the spontaneous apoptosis in an LPS-dependent manner. This delayed apoptosis could be mimicked by adding purified LPS and was also observed by using fimbriated bacteria in the presence of d-mannose. These results suggest that LPS is required for E. coli to exert both pro- and antiapoptotic effects on neutrophils and that the difference in LPS presentation (i.e., with or without fimbriae) determines the outcome. The present study showed that there is a fine-tuned balance between type 1 fimbria-induced and LPS-mediated delay of apoptosis in human neutrophils, in which altered fimbrial expression on uropathogenic E. coli determines the neutrophil survival and the subsequent inflammation during urinary tract infections.

Relative Sensitivity of Escherichia coli O157 Detection from Bovine Feces and Rectoanal Mucosal Swabs

2014 ◽  
Vol 77 (6) ◽  
pp. 972-976 ◽  
Author(s):  
K. J. WILLIAMS ◽  
M. P. WARD ◽  
O. DHUNGYEL ◽  
L. VAN BREDA
Keyword(s):  
Escherichia Coli ◽  
Confidence Interval ◽  
Human Health Risk ◽  
Relative Sensitivity ◽  
Immunomagnetic Separation ◽  
Detection Methods ◽  
Escherichia Coli O157 ◽  
Prevalence Studies ◽  
E Coli ◽  
The Difference

The need to quantify the potential human health risk posed by the bovine reservoir of Escherichia coli O157 has led to a wealth of prevalence studies and improvements in detection methods over the last two decades. Rectoanal mucosal swabs have been used for the detection of E. coli O157 fecal shedding, colonized animals, and those predisposed to super shedding. We conducted a longitudinal study to compare the detection of E. coli O157 from feces and rectoanal mucosal swabs (RAMS) from a cohort of dairy heifers. We collected 820 samples that were tested by immunomagnetic separation of both feces and RAMS. Of these, 132 were detected as positive for E. coli O157 from both samples, 66 were detected as positive from RAMS only, and 117 were detected as positive from feces only. The difference in results between the two sample types was statistically significant (P < 0.001). The relative sensitivities of detection by immunomagnetic separation were 53% (confidence interval, 46.6 to 59.3) from RAMS and 67% (confidence interval, 59.6 to 73.1) from fecal samples. No association between long-term shedding (P = 0.685) or super shedding (P = 0.526) and detection by RAMS only was observed.

scholarly journals Effect of nanoparticles on Escherichia coli growth dynamics

2019 ◽  
pp. 107-113
Author(s):  
Laith B Alhusseini
Keyword(s):  
Escherichia Coli ◽  
Titanium Dioxide ◽  
Urinary Tract ◽  
Iron Oxide ◽  
Titanium Dioxide Nanoparticles ◽  
Growth Dynamics ◽  
Inhibition Zone ◽  
E Coli ◽  
Tract Infections ◽  
The Impact

Background: Nanoparticles (iron oxide and titanium dioxide nanoparticles) are another kind of critical materials that are produced for use in various research and different purposes. The bacteriology field being so critical seek to the intrinsic understanding on the effect of nanoparticles on bacterial growth and functions. Our investigation was planned to detect the impact of iron oxide (Fe3O4), titanium dioxide (TiO2) nanoparticles on growth of Escherichia coli (Iraqi isolate). Methods: Fifty urine samples of patients, who are suffering Urinary Tract Infections (UTIs) in Iraqi hospitals, were collected. Our study was included three parts: the 1st part was isolated and diagnosed the bacteria that cause the urinary tract infection, the 2nd part was sensitivity to antibiotics, and the 3rd has used the nanomaterials and study their impacts on the growth of E. col isolates. Result: The results showed that 30 E. coli isolates depending on the properties of biochemical and molecular detect. Five common types of antibiotics were examined for the treatment of infections of the urinary tract. Most E. coli were resistant to antibiotics, the ratios of ampicillin, amikacin and augmentin found to be 90%, 82% and 80% respectively. It concluded that bacteria were sensitive to imipenem and meropenem of about 50 %. So, the effect of iron oxide and titanium dioxide nanoparticles were studied for the growth of bacteria using the agar. The effectiveness against bacteria (diameters of the inhibition zone rate) found to be 18 mm for the 1st substance and 21 mm for 2nd substance. Conclusion: Our current study indicates that there is an effect of nanoparticles at the cellular level that can be used for beneficial biological application such as antibacterial. Keywords: Escherichia coli; Inhibition zone; Antibiotics; Nanoparticles

scholarly journals Outbreaks of Escherichia coli O157:H7 Infections Linked to Romaine Lettuce in Canada from 2008 to 2018: An Analysis of Food Safety Context

2020 ◽  
Vol 83 (8) ◽  
pp. 1444-1462 ◽  
Author(s):  
GENEVIÈVE COULOMBE ◽  
ANGELA CATFORD ◽  
AMALIA MARTINEZ-PEREZ ◽  
ENRICO BUENAVENTURA
Keyword(s):  
Escherichia Coli ◽  
The United States ◽  
Escherichia Coli O157 ◽  
Romaine Lettuce ◽  
E Coli ◽  
Leafy Greens ◽  
Iceberg Lettuce ◽  
Canadian Population ◽  
The Difference ◽  
Commercial Distribution

ABSTRACT Foodborne diseases are a major cause of illness in Canada. One of the main pathogens causing cases and outbreaks of foodborne illness in Canada is Escherichia coli O157:H7. From 2008 to 2018, 11 outbreaks of E. coli O157:H7 infection in Canada were linked to leafy greens, including 7 (63.6%) linked to romaine lettuce, 2 (18.2%) linked to iceberg lettuce, and 2 (18.2%) linked to other or unspecified types of leafy greens. The consumption of lettuce in Canada, the behavior of E. coli O157:H7 on lettuce leaves, and the production practices used for romaine and iceberg lettuce do not seem to explain why a higher number of outbreaks of E. coli O157:H7 infection were linked to romaine than to iceberg lettuce. However, the difference in the shape of iceberg and romaine lettuce heads could be an important factor. Among the seven outbreaks linked to romaine lettuce in Canada between 2008 and 2018, an eastern distribution of cases was observed. Cases from western provinces were reported only twice. The consumption of romaine and iceberg lettuce by the Canadian population does not seem to explain the eastern distribution of cases observed, but the commercial distribution, travel distances, and the storage practices used for lettuce may be important factors. In the past 10 years, the majority of the outbreaks of E. coli O157:H7 infection linked to romaine lettuce occurred during the spring (March to June) and fall (September to December). The timing of these outbreaks may be explained by the availability of lettuce in Canada, the growing region transition periods in the United States, and the seasonality in the prevalence of E. coli O157:H7. The consumption of romaine lettuce by the Canadian population does not explain the timing of the outbreaks observed. HIGHLIGHTS

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