scholarly journals STUDIES ON THE MECHANISM OF THE PHOTOSENSITIZED INACTIVATION OF E. COLI AND REACTIVATION PHENOMENON

1952 ◽  
Vol 36 (2) ◽  
pp. 207-226 ◽  
Author(s):  
F. Heinmets ◽  
R. Vinegar ◽  
W. W. Taylor
Keyword(s):  
Methylene Blue ◽  
Wave Length ◽  
Action Spectrum ◽  
Prolonged Storage ◽  
Experimental Conditions ◽  
E Coli ◽  
Hydrogen Donors ◽  
Inactivation Process ◽  
Photosensitized Inactivation ◽  
Inactivation Of Bacteria

In order to find a more satisfactory interpretation of the phenomenon of photosensitized inactivation of bacteria, studies were performed under various experimental conditions on methylene blue and E. coli. In summary the findings are as follow:— 1. The dye is absorbed by the bacteria according to the Langmuir isotherm and can be removed by ionic substitutions; the dye binding to the bacteria is predominantly ionic; the dye-bacteria complex produces a new absorption peak in the 610 mµ wave length region, and the action spectrum corresponds to the spectral absorption of the dye-bacteria complex. 2. There is an optimum dye concentration range for the photosensitized inactivation. 3. Photosensitized inactivation of bacteria can take place both in the frozen and liquid states and the presence of oxygen is essential to the inactivation process. 4. Hydrogen peroxide, formed by reoxidation of the reduced methylene blue, does not inactivate bacteria. 5. Following the photosensitized inactivation, E. coli lose their ability to reduce the methylene blue in the presence of various hydrogen donors, suggesting that enzymes are involved in the inactivation process. 6. Bacteria inactivated by photosensitization can be reactivated by prolonged storage after irradiation; the recovery rate increases with increasing temperature (maximum 37°), and is also influenced by the presence of various hydrogen donors. In view of collected experimental data, the basic reaction mechanisms are analyzed in photosensitized inactivation. The first step of the reaction seems to be excitation of the dye-bacteria, or dye-bacteria oxygen complex, by a photon which produces an activated complex. In such a state, molecular oxygen is capable of producing an oxidizing reaction, which results in the inactivation of the bacteria. Some aspects of the detailed reactions taking place at the cell surface are discussed.

scholarly journals ACTION SPECTRA FOR PHOTOREACTIVATION OF ULTRAVIOLET-IRRADIATED ESCHERICHIA COLI AND STREPTOMYCES GRISEUS

1951 ◽  
Vol 34 (6) ◽  
pp. 835-852 ◽  
Author(s):  
Albert Kelner
Keyword(s):  
Escherichia Coli ◽  
Wave Length ◽  
Action Spectrum ◽  
Streptomyces Griseus ◽  
Soret Band ◽  
E Coli ◽  
Action Spectra ◽  
Effective Wave ◽  
Active Wave ◽  
Escherichia Coli B

Action spectra for photoreactivation (light-induced recovery from ultraviolet radiation injury) of Escherichia coli B/r and Streptomyces griseus ATCC 3326 were determined. The spectral region explored was 365 to 700 mµ. The action spectrum for S. griseus differed from that for E. coli, indicating that the chromophores absorbing reactivating energy in the two species were not the same. Reactivation of S. griseus occurred in the region 365 mµ (the shortest wave length studied) to about 500 mµ, with the most effective wave length lying near 436 mµ. This single sharp peak in the spectrum at 436 mµ suggested the Soret band typical of porphyrins. Reactivation of E. coli occurred in the region 365 to about 470 mµ, with the most active wave length lying near 375 mµ. The single, non-pronounced peak near 375 was probably not due to a Soret band, and the identification of the substance absorbing reactivating light in E. coli is uncertain. In neither species was the region 500 to 700 mµ active. The implications of these action spectra and their differences are discussed.

An Action Spectrum of the Riboflavin Photosensitized Inactivation of Lambda Phage

2004 ◽  
Author(s):  
Christopher B. Martin ◽  
Erin Wilfong ◽  
Patrick Ruane ◽  
Raymond Goodrich ◽  
Matthew Platz
Keyword(s):  
Action Spectrum ◽  
Lambda Phage ◽  
Photosensitized Inactivation

scholarly journals Fabrication of AgCl/Ag3PO4/graphitic carbon nitride heterojunctions for enhanced visible light photocatalytic decomposition of methylene blue, methylparaben and E. coli

RSC Advances ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 6383-6394 ◽  
Author(s):  
Haishuai Li ◽  
Linlin Cai ◽  
Xin Wang ◽  
Huixian Shi
Keyword(s):  
Methylene Blue ◽  
Visible Light ◽  
Photocatalytic Degradation ◽  
Visible Light Irradiation ◽  
Carbon Nitride ◽  
Light Irradiation ◽  
Graphitic Carbon Nitride ◽  
Photocatalytic Decomposition ◽  
E Coli ◽  
Visible Light Photocatalytic

A noval ternary nanocomposite AgCl/Ag3PO4/g-C3N4 was successfully synthesized for photocatalytic degradation of methylene blue, methylparaben and inactivation of E. coli under visible light irradiation, showing excellent photocatalytic degradation performance and stability.

Photocatalytic Degradation of Methylene Blue over Co-Ag3VO4 under Visible Light Irradiation

2011 ◽  
Vol 335-336 ◽  
pp. 1385-1390 ◽  
Author(s):  
Shuo Wiei Zhao ◽  
Hui Xu ◽  
Hua Ming Li ◽  
Yuan Guo Xu
Keyword(s):  
Methylene Blue ◽  
Photocatalytic Activity ◽  
Visible Light ◽  
Visible Light Irradiation ◽  
Absorption Edge ◽  
Diffuse Reflectance Spectroscopy ◽  
Dye Degradation ◽  
Light Irradiation ◽  
Experimental Conditions ◽  
X Ray

In order to improve the photocatalytic activity, Co was successfully loaded into Ag3VO4 by using impregnation process. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS) and diffuse reflectance spectroscopy (DRS). The XRD and SEM–EDS analyses revealed that Co ion was dispersed on Ag3VO4. The DRS results indicated that the absorption edge of the Co–Ag3VO4 catalyst shifted to longer wavelength. The enhanced photocatalytic activity of Co–Ag3VO4 for Methylene Blue(MB) dye degradation under visible light irradiation was due to its wider absorption edge and higher separation rate of photo-generated electron and holes. In the experimental conditions, it is demonstrated that the MB was effectively degraded by more than 95% within 40 min when the Co–Ag3VO4 catalyst was calcined at 300°C with 1 wt.% Co content.

Schistosoma mansoni: tail loss in relation to permeability changes during cercaria–schistosomulum transformation

Parasitology ◽  
1975 ◽  
Vol 71 (1) ◽  
pp. 9-18 ◽  
Author(s):  
R. E. Howells ◽  
S. E. Gerken ◽  
F. J. Pinto-Ramalho ◽  
U. Kawazoe ◽  
G. Gazzinelli ◽  
...  
Keyword(s):  
Amino Acids ◽  
Methylene Blue ◽  
Schistosoma Mansoni ◽  
Body Region ◽  
Experimental Conditions ◽  
General Body ◽  
Tail Loss ◽  
Permeability Changes ◽  
Extensive Lesion ◽  
Scanning Electron

The hind-body region of Schistosoma mansoni cercariae observed in the scanning electron microscope demonstrates various stages of contraction which may be compared with those of living larvae which are secreting the acetabular gland contents.No evidence for an extensive lesion was found in cercarial bodies which had shed their tails under experimental conditions. Experiments on the permeability of the larvae to sodium fluoride, methylene blue and amino acids demonstrated that tail loss significantly affects the permeability of the bodies although the effect is greater immediately after decaudation than at later times. Subsequent increases in permeability may be correlated with a change in the general body surface.

Temperature Dependent On Activated Carbon For Their Biological Activity And Photocatalytical Degradation of Methylene Blue: A Novel Approach To Green Synthesis

2021 ◽  
Author(s):  
Amalanathan.M ◽  
Aravind.M ◽  
Sony Michael Mary.M ◽  
Razan A. Alshgari ◽  
Asma A. Alothman ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Antibacterial Activity ◽  
Activated Carbon ◽  
Hydrothermal Carbonization ◽  
Microbial Pathogens ◽  
X Ray Diffraction ◽  
E Coli ◽  
Novel Approach ◽  
Transmission Electron ◽  
Ft Ir

Abstract In this work, jasmine flower derived activated carbon were successfully synthesized by hydrothermal carbonization process at the different annealing temperature. The Crystallinity, phase, structural, morphological and optical properties of activated carbon were investigated using X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), Transmission electron microscope (TEM), and UV-visible spectroscopy analysis. The graphitic phase of carbon was obtained from the XRD pattern. Surface morphology reveals irregular-shaped nanoparticles. The photodegradation of methylene blue (MB) was carried out under the visible light irradiation technique to study its photocatalytic activity. The activated carbon obtained at 400oC, 500oC and 600oC shows a photocatalytic degradation efficiency of 86%, 90%, and 94%, respectively. Antibacterial activity of activated carbon was examined against S. Aureus (MTCC-737) and E-Coli (MTCC- 443) microbial pathogens, and their potent antibacterial activity was examined from the zone of inhibition layer.

Characteristics of Packaged Water under Different Storage Conditions Within Osogbo Metropolis

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
O.O Fadipe
Keyword(s):  
Room Temperature ◽  
Control Unit ◽  
Storage Conditions ◽  
Prolonged Storage ◽  
E Coli ◽  
Physico Chemical ◽  
Routine Basis ◽  
Regulatory Bodies ◽  
Microbiological Analyses ◽  
Sachet Water

The study investigated the characteristics of packaged water stored under ambient and sunlight conditions. This is with a view to testing the effect of prolonged storage under different storage conditions on its quality. In addition it analyzed the interactions between the parameters. Two packs each of bottled and sachet water was purchased from each factory at the point of production and ready for distribution to wholesalers. Twenty eight pieces of packaged water from each factory were kept at room temperature and the same quantity were kept under sunlight. Physico-chemical and microbiological analyses were carried out on the remaining packaged water within 24hrs. Half of the samples stored at the two storage conditions were removed for analysis at 3 weeks while the remaining half was analyzed after 6weeks. The physico-chemical characteristics were within the WHO recommended values except for the pH of some samples that have values in the acidic range of 6.2-6.48. All the physico-chemical values increased for samples kept under sunlight. All the water samples showed growth in faecal coliform (4-46 cfu/100 mL) and E. coli (0-13 cfu/100 mL) for samples kept under sunlight at three weeks and this growth increased to the sixth week. The presence of E. coli is an indication that the packaged water is not pure. Displaying packaged water under the sunlight and storing beyond 3 weeks by vendors have effect on the potability of the product. The regulatory bodies should raise awareness and ensure manufacturer have a quality control unit to test on a routine basis.

scholarly journals Induction of Viable but Nonculturable Escherichia coli O157:H7 in the Phyllosphere of Lettuce: a Food Safety Risk Factor

2011 ◽  
Vol 77 (23) ◽  
pp. 8295-8302 ◽  
Author(s):  
Laura-Dorina Dinu ◽  
Susan Bach
Keyword(s):  
Escherichia Coli ◽  
Food Safety ◽  
Low Temperature ◽  
Cell Density ◽  
Prolonged Storage ◽  
Potential Hazard ◽  
Vbnc State ◽  
Viable But Nonculturable ◽  
Content Type ◽  
E Coli

ABSTRACTEscherichia coliO157:H7 continues to be an important human pathogen and has been increasingly linked to food-borne illness associated with fresh produce, particularly leafy greens. The aim of this work was to investigate the fate ofE. coliO157:H7 on the phyllosphere of lettuce under low temperature and to evaluate the potential hazard of viable but nonculturable (VBNC) cells induced under such stressful conditions. First, we studied the survival of six bacterial strains following prolonged storage in water at low temperature (4°C) and selected two strains with different nonculturable responses for the construction ofE. coliO157:H7 Tn7gfptransformants in order to quantitatively assess the occurrence of human pathogens on the plant surface. Under a suboptimal growth temperature (16°C), bothE. coliO157:H7 strains maintained culturability on lettuce leaves, but under more stressful conditions (8°C), the bacterial populations evolved toward the VBNC state. The strain-dependent nonculturable response was more evident in the experiments with different inoculum doses (109and 106E. coliO157:H7 bacteria per g of leaf) when strain BRMSID 188 lost culturability after 15 days and strain ATCC 43895 lost culturability within 7 days, regardless of the inoculum dose. However, the number of cells entering the VBNC state in high-cell-density inoculum (approximately 55%) was lower than in low-cell-density inoculum (approximately 70%). We recorded the presence of verotoxin for 3 days in samples that contained a VBNC population of 4 to 5 log10cells but did not detect culturable cells. These findings indicate thatE. coliO157:H7 VBNC cells are induced on lettuce plants, and this may have implications regarding food safety.

In-toilet disinfection of fresh fecal sludge with ammonia naturally present in excreta

2015 ◽  
Vol 6 (1) ◽  
pp. 104-114 ◽  
Author(s):  
Temitope A. Ogunyoku ◽  
Fikreselam Habebo ◽  
Kara L. Nelson
Keyword(s):  
Escherichia Coli ◽  
Closed System ◽  
Treatment Method ◽  
Second Step ◽  
Dominant Form ◽  
E Coli ◽  
Fecal Sludge ◽  
Ph Level ◽  
Inactivation Of Bacteria ◽  
Control Samples

A simple treatment method, Safe Sludge disinfection, was developed to disinfect pathogens in fresh fecal sludge using the ammonia naturally present in excreta. In the first step, urea is hydrolyzed to ammonia (NH3/NH4+). In the second step, Ca(OH)2 is added to raise the pH level such that NH3, a known disinfectant, is the dominant form of ammonia; subsequently, the waste is stored until sufficient disinfection is achieved. In a closed system at 23 °C, Safe Sludge disinfection achieved >9.3 log10 and >4.0 log10 decrease of indigenous Escherichia coli and seeded MS2 coliphage, respectively, within 10.6 hours, and 2.0 log10 inactivation of seeded Ascaris suum eggs within 2 weeks. Disinfection of feces at high pH with no urine addition was tested for comparison, and similar inactivation levels were achieved for E. coli and MS2 bacteriophage. However, for Ascaris eggs only 0.38 log10 inactivation was achieved over 2 weeks. For control samples (feces plus urine only), no inactivation of bacteria or virus indicators was observed and inactivation of Ascaris eggs was also low (0.42 log10). To illustrate how the Safe Sludge concept could be incorporated into a waterless household toilet, a conceptual design and prototype was developed, called the pHree Loo.

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