Effect of TiO2 Loading, Water Depth and Light Intensity on Photo-Disinfection Efficacy of Escherichia Coli O157:H7 Using TiO2 NP-Embedded Cellulose Acetate Film in Water

2021 ◽  
Vol 37 (1) ◽  
pp. 1-9
Author(s):  
Jing Xie ◽  
Yen-Con Hung
Keyword(s):  
Escherichia Coli ◽  
Light Intensity ◽  
Cellulose Acetate ◽  
Water Depth ◽  
Coefficient Of Determination ◽  
List Type ◽  
Water Safety ◽  
Operational Parameters ◽  
Bacterial Reduction ◽  
E Coli

HighlightsPhoto-disinfection using TiO2 NP-embedded CA film showed great potential.TiO2 loading, water depth, and light intensity affected TiO2 photo-disinfection.Bacterial reduction can be predicted based on water depth and light intensity.Durability of the TiO2 NP-embedded CA film has been demonstrated.Abstract. Photocatalysis disinfection has great potential for food and water safety applications. TiO2 NP-embedded cellulose acetate (CA) film has shown effectiveness in inactivating Escherichia coli (E. coli) O157:H7 in water. This study evaluated the effect of several operational parameters such as TiO2 load, light intensity, and water depth on photo-disinfection efficacy of TiO2 NP-embedded CA film. Effect of TiO2 load on photocatalysis disinfection efficacy was investigated by assessing the disinfection rate of the films at different TiO2 levels in inoculated water at a weak UV-A light intensity. The individual and interaction effects of light intensity and water depth on photocatalysis disinfection were evaluated using the response surface methodology (RSM). Based on a central composite design, 13 runs of experiments were conducted with the combination of the two factors at three levels. The effect of film size on photo-disinfection efficacy was also investigated. Results showed that CA film with a TiO2 load of 0.82 mg/cm2 yielded the highest disinfection rate. An empirical model was established to predict the effect of light intensity and water depth on bacterial reduction with a high coefficient of determination (R2 = 0.98). An increased water depth or a decreased light intensity reduced photo-inactivation efficacy. A 5 log reduction was achieved during a 3-h treatment at a light intensity of 1 mW/cm2 and water depth at 1.6 cm. The photo-disinfection efficacy of the film was not significantly (p>0.05) affected by film size. The CA film was able to maintain antimicrobial efficacy after four repeated uses. Results from this study demonstrated that UV-A assisted photo-disinfection using TiO2 NP-embedded CA film has great potential to inactivate pathogens in water. Keywords: Cellulose Acetate, E. coli O157:H7, Photocatalysis, TiO2 nanoparticles, Water Treatment.

scholarly journals The Evolution of Mass Cell Suicide in Bacterial Warfare

2020 ◽  
Author(s):  
Elisa T. Granato ◽  
Kevin R. Foster
Keyword(s):  
Escherichia Coli ◽  
Natural Selection ◽  
Reproductive Potential ◽  
Time Lapse ◽  
List Type ◽  
E Coli ◽  
Toxin Exposure ◽  
Small Benefit ◽  
Will Self ◽  
Cell Suicide

SUMMARYBehaviours that reliably cause the death of an actor are typically strongly disfavoured by natural selection, and yet many bacteria undergo cell lysis to release anti-competitor toxins [1–4]. This behaviour is most easily explained if only a few cells die to release toxins and help their clonemates, but the number of cells that actually lyse during bacterial warfare is unknown. The challenge is that one cannot distinguish cells that have undergone programmed suicide from those that were simply killed by a competitor’s toxin. We developed a two-colour fluorescence reporter assay in Escherichia coli to overcome this problem. Surprisingly, this revealed conditions where nearly all cells undergo programmed lysis. Adding a DNA-damaging toxin (DNase colicin) to a focal strain causes it to engage in mass cell suicide where around 85% of cells lyse to release their own toxin. Time-lapse 3D confocal microscopy revealed that self-lysis occurs at even higher frequencies (~94%) at the interface between competing colonies. We sought to understand how such high levels of cell suicide could be favoured by natural selection. Exposing E. coli that do not perform lysis to the DNase colicin revealed that mass lysis only occurs when cells are going to die anyway from toxin exposure. From an evolutionary perspective, this renders the behaviour cost-free as these cells have zero reproductive potential. This explains how mass cell suicide can evolve, as any small benefit to surviving clonemates can lead to the strategy being favoured by natural selection. Our findings have strong parallels to the suicidal attacks of social insects [5–8], which are also performed by individuals with low reproductive potential, suggesting convergent evolution in these very different organisms.HIGHLIGHTSA novel assay can detect Escherichia coli undergoing cell suicide to release toxinsWe quantified the frequency of suicidal self-lysis during competitionsUnder some conditions, nearly all cells will self-lyse to release toxinsSelf-lysis makes evolutionary sense as cells will die anyway from competitors’ toxins

scholarly journals Fabrication and Super-Antibacterial Property of Nanosilver/Sericin/Poly(ethylene oxide) Nanofibers through Electrospinning-Combined Postdeposition Method

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Jia Li ◽  
Bo-Xiang Wang ◽  
Yi-Fan Cui ◽  
Zhi-Cai Yu ◽  
Xu Hao ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Ethylene Oxide ◽  
Antibacterial Property ◽  
Silver Content ◽  
Antibacterial Properties ◽  
Bacterial Reduction ◽  
E Coli ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Nanofiber Mats

Nanosilver particle has been used in the nanofiber mats by mixing the nanosilver with the spinning solution for improving the antibacterial property. Although studies have shown that the antibacterial property of nanofiber mats gets increasing, the higher silver content and the larger released resistance of nanosilver from nanofiber mats are obvious. Here, the electrospinning-combined postdeposition method was used to prepare the nanosilver/sericin/poly(ethylene oxide) (Ag/SS/PEO) nanofiber mats and the bacterial reduction rates againstStaphylococcus aureus(S. aureus) andEscherichia coli(E. coli) were analyzed. We found that the Ag/SS/PEO nanofiber mats were excellent antibacterial properties at the lower silver content and the bacterial reduction rates againstS. aureusandE. coliall reached above 99.99%. Our data suggests that the antibacterial property can be improved by introducing the electrospinning-combined postdeposition method.

scholarly journals Physical Covering for Control of Escherichia coli O157:H7 and Salmonella spp. in Static and Windrow Composting Processes

2015 ◽  
Vol 81 (6) ◽  
pp. 2063-2074 ◽  
Author(s):  
Jitendra R. Patel ◽  
Irene Yossa ◽  
Dumitru Macarisin ◽  
Patricia Millner
Keyword(s):  
Escherichia Coli ◽  
Escherichia Coli O157 ◽  
Bacterial Reduction ◽  
Salmonella Spp ◽  
Rapid Reduction ◽  
Content Type ◽  
E Coli ◽  
Windrow Composting ◽  
Composting Systems ◽  
Feedstock Material

ABSTRACTThis study investigated the effect of a 30-cm covering of finished compost (FC) on survival ofEscherichia coliO157:H7 andSalmonellaspp. in active static and windrow composting systems. Feedstocks inoculated withE. coliO157:H7 (7.41 log CFU/g) andSalmonella(6.46 log CFU/g) were placed in biosentry tubes (7.5-cm diameter, 30-cm height) at three locations: (i and ii) two opposing sides at the interface between the FC cover layer (where present) and the feedstock material (each positioned approximately 10 cm below the pile's surface) and (iii) an internal location (top) (approximately 30 cm below the surface). On specific sampling days, surviving populations of inoculatedE. coliO157:H7 andSalmonella, genericE. coli, and coliforms in compost samples were determined.Salmonellaspp. were reduced significantly within 24 h in windrow piles and were below the detection limit after 3 and 7 days at internal locations of windrow and static piles containing FC covering, respectively. Likewise,E. coliO157:H7 was undetectable after 1 day in windrow piles covered with finished compost. Use of FC as a covering layer significantly increased the number of days that temperatures in the windrows remained ≥55°C at all locations and in static piles at internal locations. These time-temperature exposures resulted in rapid reduction of inoculated pathogens, and the rate of bacterial reduction was rapid in windrow piles. The sample location significantly influenced the survival of these pathogens at internal locations compared to that at interface locations of piles. Finished compost covering of compost piles aids in the reduction of pathogens during the composting process.

Inactivation of Listeria innocua, Salmonella Typhimurium, and Escherichia coli O157:H7 on Surface and Stem Scar Areas of Tomatoes Using In-Package Ozonation†

2012 ◽  
Vol 75 (9) ◽  
pp. 1611-1618 ◽  
Author(s):  
XUETONG FAN ◽  
KIMBERLY J. B. SOKORAI ◽  
JÜRGEN ENGEMANN ◽  
JOSHUA B. GURTLER ◽  
YANHONG LIU
Keyword(s):  
Escherichia Coli ◽  
Salmonella Typhimurium ◽  
Treatment Time ◽  
Listeria Innocua ◽  
Escherichia Coli O157 ◽  
Bacterial Reduction ◽  
Negative Effects ◽  
E Coli ◽  
Storage Study ◽  
Proportional Increase

A novel in-package ozonation device was evaluated for its efficacy in inactivating three microorganisms (viz., Listeria innocua, attenuated Salmonella Typhimurium, and Escherichia coli O157:H7) on tomatoes and for its effect on fruit quality. The device produced ozone inside sealed film bags, reaching a concentration of 1,000 ppm within 1 min of activation. The three bacterial cultures were inoculated onto either the smooth surface or the stem scar areas of the tomatoes, which were then sealed in plastic film bags and subjected to in-package ozonation. L. innocua on tomatoes was reduced to nondetectable levels within 40 s of treatment on the tomato surface, with inactivation of ca. 4 log CFU per fruit on the stem scar area. An increase in treatment time did not result in a proportional increase in bacterial reduction. For E. coli O157:H7 and Salmonella, there was little difference (<1 log) in the effectiveness of the system when comparing surface and scar-inoculated bacteria. Both bacteria were typically reduced by 2 to 3 log CFU per fruit after 2- to 3-min treatments. No negative effects on fruit color or texture were observed during a 22-day posttreatment storage study of ozone-treated tomatoes. These results suggest that the three bacteria responded differently to ozonation and that in-package ozonation may provide an alternative to chemical sanitizers commonly used by the industry.

A RIBOSOMAL PEPTIDASE FROM ESCHERICHIA COLI B

1965 ◽  
Vol 43 (3) ◽  
pp. 323-329 ◽  
Author(s):  
A. T. Matheson ◽  
C. S. Tsai
Keyword(s):  
Escherichia Coli ◽  
Enzyme Activity ◽  
Ribosomal Protein ◽  
Cellulose Acetate ◽  
Density Gradient ◽  
Sucrose Density Gradient ◽  
E Coli ◽  
Ribosome Structure ◽  
Escherichia Coli B

Properties of a peptidase present in E. coli ribosomes have been studied. The enzyme is tightly bound to the ribosomes, as indicated by repeated washings and centrifugations, sucrose density gradient centrifugations, and electrophoresis on cellulose acetate. The level of enzyme activity in the 30 S particles is twice that found in the 50 S particles. When the ribosome structure is disrupted by enzymic or chemical means, the peptidase behaves similarly to the bulk of the ribosomal protein.

scholarly journals Biofunctionalization of Cork with Moringa oleifera Seeds and Use of PMA Staining and qPCR to Detect Viability of Escherichia coli

Water ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 2731
Author(s):  
Nury Infante ◽  
Refugio Rodríguez ◽  
Yaneth Bartolo ◽  
Olga Sánchez ◽  
Isabel Sanz ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Moringa Oleifera ◽  
Antibacterial Properties ◽  
Fractional Factorial ◽  
Target Sequence ◽  
Lacz Gene ◽  
Bacterial Reduction ◽  
E Coli ◽  
Polymerase Chain ◽  
Seed Extracts

Cork matrices biofunctionalized with Moringa oleifera seed extracts (MoSe) have potential for use as a biofilter with antibacterial properties to reduce waterborne pathogens. The aim of this study was to evaluate the effect of cork biofunctionalized with active antimicrobial compounds of MoSe (f-cork) on the inhibition of Escherichia coli (InhEc). The LacZ gene from a strain of E. coli was used as the target sequence using viability quantification Polymerase Chain Reaction (qPCR) and differentiation of viable and dead bacteria through selective cell viability PMA staining. To perform this, a 27−4 fractional factorial design and a biofiltration system were used to evaluate the effect of the active protein in MoSe immobilized in granulated cork on InhEc. We found that the potential for antimicrobial activity increased with f-cork for an effective maximal bacterial reduction (99.99%; p < 0.05). The effect of f-cork functionalized with MoSe on E. coli viability was of 0.024% and 0.005% for the cells exposed to PMA, respectively, being the relevant conditions in treatment 2: (0 L/min) without aeration, (5%) MoSe and (5 mm) cork particle. In conclusion, the f-cork functionalized with MoSe presented biosorbent and antibacterial properties that effectively reduced the E. coli growth.

scholarly journals Application of DVC-FISH method in tracking Escherichia coli in drinking water distribution networks

2013 ◽  
Vol 6 (1) ◽  
pp. 25-31 ◽  
Author(s):  
L. Mezule ◽  
S. Larsson ◽  
T. Juhna
Keyword(s):  
Escherichia Coli ◽  
Drinking Water ◽  
Distribution System ◽  
Water Distribution ◽  
Water Distribution System ◽  
Distribution Networks ◽  
Water Distribution Networks ◽  
Water Safety ◽  
E Coli ◽  
Drinking Water Distribution

Abstract. Sporadic detection of live (viable) Escherichia coli in drinking water and biofilm with molecular methods but not with standard plate counts has raised concerns about the reliability of this indicator in the surveillance of drinking water safety. The aim of this study was to determine spatial distribution of different viability forms of E. coli in a drinking water distribution system which complies with European Drinking Water Directive (98/83/EC). For two years coupons (two week old) and pre-concentrated (100 times with ultrafilters) water samples were collected after treatment plants and from four sites in the distribution network at several distances. The samples were analyzed for total, viable (able to divide as DVC-FISH positive) and cultivable E. coli. The results showed that low numbers of E. coli enters the distribution sytem from the treatment plants and tend to accumulate in the biofilm of water distribution system. Almost all of the samples contained metabolically active E. coli in the range of 1 to 50 cells per litre or cm2 which represented approximately 53% of all E. coli detected. The amount of viable E. coli significantly increased into the network irrespective of the season. The study has shown that DVC-FISH method in combination with water pre-concentration and biofilm sampling allows to better understand the behaviour of E. coli in water distribution networks, thus, it provides new evidences for water safety control.

Photocatalytic bactericidal activity of TiO2 in aqueous suspensions of E. coli

1997 ◽  
Vol 35 (11-12) ◽  
pp. 95-100 ◽  
Author(s):  
M. Bekbölet
Keyword(s):  
Escherichia Coli ◽  
Light Intensity ◽  
Bactericidal Activity ◽  
Inactivation Rate ◽  
Tio2 Anatase ◽  
E Coli ◽  
Aqueous Suspensions ◽  
Photocatalytic Bactericidal Activity ◽  
Effect Of Light

Aqueous suspensions of Escherichia coli and TiO2 (anatase) were irradiated with a BLF lamp (320nm&lt;λ&lt;420nm). The inactivation rate for an initial E. coli level of 103 cells/mL was 1.78×10−2/min for light intensity of 67.9μE/s.m2 in the presence of 1mg/mL TiO2. Optimum TiO2 loading and the effect of light intensity are also reported.

Evaluation of Lactic Acid as an Initial and Secondary Subprimal Intervention for Escherichia coli O157:H7, Non-O157 Shiga Toxin–Producing E. coli, and a Nonpathogenic E. coli Surrogate for E. coli O157:H7

2012 ◽  
Vol 75 (9) ◽  
pp. 1701-1708 ◽  
Author(s):  
C. I. PITTMAN ◽  
I. GEORNARAS ◽  
D. R. WOERNER ◽  
K. K. NIGHTINGALE ◽  
J. N. SOFOS ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Lactic Acid ◽  
Shiga Toxin ◽  
Hazard Analysis ◽  
Control Point ◽  
Escherichia Coli O157 ◽  
Meat Industry ◽  
Bacterial Reduction ◽  
E Coli ◽  
Critical Control Point

Lactic acid can reduce microbial contamination on beef carcass surfaces when used as a food safety intervention, but effectiveness when applied to the surface of chilled beef subprimal sections is not well documented. Studies characterizing bacterial reduction on subprimals after lactic acid treatment would be useful for validations of hazard analysis critical control point (HACCP) systems. The objective of this study was to validate initial use of lactic acid as a subprimal intervention during beef fabrication followed by a secondary application to vacuum-packaged product that was applied at industry operating parameters. Chilled beef subprimal sections (100 cm2) were either left uninoculated or were inoculated with 6 log CFU/cm2 of a 5-strain mixture of Escherichia coli O157:H7, a 12-strain mixture of non-O157 Shiga toxin–producing E. coli (STEC), or a 5-strain mixture of nonpathogenic (biotype I) E. coli that are considered surrogates for E. coli O157:H7. Uninoculated and inoculated subprimal sections received only an initial or an initial and a second “rework” application of lactic acid in a custom-built spray cabinet at 1 of 16 application parameters. After the initial spray, total inoculum counts were reduced from 6.0 log CFU/cm2 to 3.6, 4.4, and 4.4 log CFU/cm2 for the E. coli surrogates, E. coli O157:H7, and non-O157 STEC inoculation groups, respectively. After the second (rework) application, total inoculum counts were 2.6, 3.2, and 3.6 log CFU/cm2 for the E. coli surrogates, E. coli O157:H7, and non-O157 STEC inoculation groups, respectively. Both the initial and secondary lactic acid treatments effectively reduced counts of pathogenic and nonpathogenic strains of E. coli and natural microflora on beef subprimals. These data will be useful to the meat industry as part of the HACCP validation process.

scholarly journals Construction and optimization of a heterologous pathway for protocatechuate catabolism inEscherichia colienables rapid bioconversion of model lignin monomers

2017 ◽  
Author(s):  
Sonya M. Clarkson ◽  
Donna M. Kridelbaugh ◽  
James G. Elkins ◽  
Adam M. Guss ◽  
Joshua K. Michener
Keyword(s):  
Escherichia Coli ◽  
Sole Source ◽  
Biofuel Production ◽  
List Type ◽  
Cellulosic Biofuels ◽  
E Coli ◽  
Gene Pathway ◽  
Cellulosic Biofuel ◽  
Fuels And Chemicals ◽  
Heterologous Pathway

AbstractCellulosic biofuel production yields a substantial lignin byproduct stream that currently has few applications. Biological conversion of lignin compounds into chemicals and fuels has the potential to improve the economics of cellulosic biofuels, but few microbes are able both to catabolize lignin and generate valuable products. WhileEscherichia colihas been engineered to produce a variety of fuels and chemicals, it is incapable of catabolizing most aromatic compounds. Therefore, we have engineeredE. colito catabolize a model lignin monomer, protocatechuate, as the sole source of carbon and energy, via heterologous expression of a nine-gene pathway fromPseudomonas putidaKT2440. We next used experimental evolution to select for mutations that increased growth with PCA more than two-fold. Increasing the strength of a single ribosome binding site in the heterologous pathway was sufficient to recapitulate the increased growth. After optimization of the core pathway, we extended the pathway to enable catabolism of a second model compound, 4-hydroxybenzoate. These engineered strains will be useful platforms to discover, characterize, and optimize pathways for lignin bioconversions.HighlightsA heterologous pathway for PCA catabolism was transferred to Escherichia coli.Evolution identified a mutation that increased growth with PCA by 2.5-fold.Optimization plus further engineering allowed efficient catabolism of 4-HB

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