scholarly journals Evaluation of non-thermal effect of microwave radiation and its mode of action in bacterial cell inactivation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Priyanka Shaw ◽  
Naresh Kumar ◽  
Sohail Mumtaz ◽  
Jun Sup Lim ◽  
Jung Hyun Jang ◽  
...  
Keyword(s):  
Thermal Effect ◽  
Microwave Radiation ◽  
Bacterial Cell ◽  
Mode Of Action ◽  
Surface Damage ◽  
Peak Frequency ◽  
Viable Count ◽  
Bacterial Inactivation ◽  
Bacterial Strains ◽  
Log Reduction

AbstractA growing body of literature has recognized the non-thermal effect of pulsed microwave radiation (PMR) on bacterial systems. However, its mode of action in deactivating bacteria has not yet been extensively investigated. Nevertheless, it is highly important to advance the applications of PMR from simple to complex biological systems. In this study, we first optimized the conditions of the PMR device and we assessed the results by simulations, using ANSYS HFSS (High Frequency Structure Simulator) and a 3D particle-in-cell code for the electron behavior, to provide a better overview of the bacterial cell exposure to microwave radiation. To determine the sensitivity of PMR, Escherichia coli and Staphylococcus aureus cultures were exposed to PMR (pulse duration: 60 ns, peak frequency: 3.5 GHz) with power density of 17 kW/cm2 at the free space of sample position, which would induce electric field of 8.0 kV/cm inside the PBS solution of falcon tube in this experiment at 25 °C. At various discharges (D) of microwaves, the colony forming unit curves were analyzed. The highest ratios of viable count reductions were observed when the doses were increased from 20D to 80D, which resulted in an approximate 6 log reduction in E. coli and 4 log reduction in S. aureus. Moreover, scanning electron microscopy also revealed surface damage in both bacterial strains after PMR exposure. The bacterial inactivation was attributed to the deactivation of oxidation-regulating genes and DNA damage.

Bactericidal Activity of Chlorine Dioxide against Escherichia coli in Water and on Hard Surfaces

1998 ◽  
Vol 61 (6) ◽  
pp. 668-672 ◽  
Author(s):  
ROBERTO FOSCHINO ◽  
ILARIA NERVEGNA ◽  
ANTONELLA MOTTA ◽  
ANTONIETTA GALLI
Keyword(s):  
Escherichia Coli ◽  
Chlorine Dioxide ◽  
Steel Surface ◽  
Aqueous Suspension ◽  
Viable Count ◽  
Linear Functions ◽  
Bacterial Inactivation ◽  
Experimental Conditions ◽  
Log Reduction ◽  
Fold Reduction

The efficacy of chlorine dioxide as a disinfectant was evaluated against cells of Escherichia coli ATCC 11229 in aqueous suspension and adhering to the surfaces of stainless steel AISI 304 and PVC. The concentrations tested ranged from 0.7 to 14 mg/liter; the exposure times investigated were 30 s and 1, 2, 4, and 8 min. When the bacteria were suspended in water with 1.4 mg/liter of chlorine dioxide, a 105-fold reduction of the initial viable count occurred within 30 s; when cells were attached to the steel surface, the same rate of inactivation took place only after 6 min with 7 mg/liter or 4 min with 14 mg/liter of chlorine dioxide. A 5-log reduction was not obtained when organisms were adhered to polyvinyl chloride (PVC). Scanning electron microscope micrographs of contaminated surfaces revealed that the PVC was very rough with pores much larger in diameter than the cells. Time values determining a 90% reduction of the E. coli population (90% killing time) were calculated for each concentration of disinfectant tested in suspension and on the steel surface. If the same experimental conditions were strictly adopted, linear functions of the log of bacterial inactivation could be plotted (log 90% killing time versus log concentration of disinfectant). This work showed that results obtained with suspension tests could not be used to estimate disinfection of hard surfaces.

scholarly journals Ventilation-Associated Particulate Matter Is a Potential Reservoir of Multidrug-Resistant Organisms in Health Facilities

Life ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 639
Author(s):  
Evgenia Chezganova ◽  
Olga Efimova ◽  
Vera Sakharova ◽  
Anna Efimova ◽  
Sergey Sozinov ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Prevalence Ratio ◽  
Multidrug Resistant ◽  
Viable Count ◽  
Health Facilities ◽  
Hospital Environment ◽  
Bacterial Strains ◽  
Multidrug Resistant Organisms ◽  
Potential Reservoir ◽  
Healthcare Associated

Most healthcare-associated infections (HCAIs) develop due to the colonisation of patients and healthcare workers by multidrug-resistant organisms (MDRO). Here, we investigated whether the particulate matter from the ventilation systems (Vent-PM) of health facilities can harbour MDRO and other microbes, thereby acting as a potential reservoir of HCAIs. Dust samples collected in the ventilation grilles and adjacent air ducts underwent a detailed analysis of physicochemical properties and biodiversity. All Vent-PM samples included ultrafine PM capable of reaching the alveoli. Strikingly, >70% of Vent-PM samples were contaminated, mostly by viruses (>15%) or multidrug-resistant and biofilm-producing bacterial strains (60% and 48% of all bacteria-contaminated specimens, respectively). Total viable count at 1 m from the ventilation grilles was significantly increased after opening doors and windows, indicating an association between air flow and bacterial contamination. Both chemical and microbial compositions of Vent-PM considerably differed across surgical vs. non-surgical and intensive vs. elective care units and between health facilities located in coal and chemical districts. Reduced diversity among MDRO and increased prevalence ratio in multidrug-resistant to the total Enterococcus spp. in Vent-PM testified to the evolving antibiotic resistance. In conclusion, we suggest Vent-PM as a previously underestimated reservoir of HCAI-causing pathogens in the hospital environment.

scholarly journals Plasma-Activated Water (PAW) as a Disinfection Technology for Bacterial Inactivation with a Focus on Fruit and Vegetables

Foods ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 166
Author(s):  
Aswathi Soni ◽  
Jonghyun Choi ◽  
Gale Brightwell
Keyword(s):  
Fruit And Vegetables ◽  
Atmospheric Plasma ◽  
Model Systems ◽  
Thermal Treatments ◽  
Bacterial Cells ◽  
Bacterial Inactivation ◽  
Gas Temperature ◽  
Bacterial Strains ◽  
Sensory Qualities ◽  
Plasma Activated Water

Plasma-activated water (PAW) is generated by treating water with cold atmospheric plasma (CAP) using controllable parameters, such as plasma-forming voltage, carrier gas, temperature, pulses, or frequency as required. PAW is reported to have lower pH, higher conductivity, and higher oxygen reduction potential when compared with untreated water due to the presence of reactive species. PAW has received significant attention from researchers over the last decade due to its non-thermal and non-toxic mode of action especially for bacterial inactivation. The objective of the current review is to develop a summary of the effect of PAW on bacterial strains in foods as well as model systems such as buffers, with a specific focus on fruit and vegetables. The review elaborated the properties of PAW, the effect of various treatment parameters on its efficiency in bacterial inactivation along with its usage as a standalone technology as well as a hurdle approach with mild thermal treatments. A section highlighting different models that can be employed to generate PAW alongside a direct comparison of the PAW characteristics on the inactivation potential and the existing research gaps are also included. The mechanism of action of PAW on the bacterial cells and any reported effects on the sensory qualities and shelf life of food has been evaluated. Based on the literature, it can be concluded that PAW offers a significant potential as a non-chemical and non-thermal intervention for bacterial inactivation, especially on food. However, the applicability and usage of PAW depend on the effect of environmental and bacterial strain-based conditions and cost-effectiveness.

scholarly journals Characterization of the Antibacterial Activity of an SiO2 Nanoparticular Coating to Prevent Bacterial Contamination in Blood Products

Antibiotics ◽  
2022 ◽  
Vol 11 (1) ◽  
pp. 107
Author(s):  
Sahra Fonseca ◽  
Marie-Pierre Cayer ◽  
K. M. Tanvir Ahmmed ◽  
Nima Khadem-Mohtaram ◽  
Steve J. Charette ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Bacterial Contamination ◽  
Polymeric Materials ◽  
L929 Cell ◽  
Bacterial Strains ◽  
Transmitted Infection ◽  
Log Reduction ◽  
Plasticized Pvc ◽  
Transfusion Transmitted Infection ◽  
Field Electron Microscopy

Technological innovations and quality control processes within blood supply organizations have significantly improved blood safety for both donors and recipients. Nevertheless, the risk of transfusion-transmitted infection remains non-negligible. Applying a nanoparticular, antibacterial coating at the surface of medical devices is a promising strategy to prevent the spread of infections. In this study, we characterized the antibacterial activity of an SiO2 nanoparticular coating (i.e., the “Medical Antibacterial and Antiadhesive Coating” [MAAC]) applied on relevant polymeric materials (PM) used in the biomedical field. Electron microscopy revealed a smoother surface for the MAAC-treated PM compared to the reference, suggesting antiadhesive properties. The antibacterial activity was tested against selected Gram-positive and Gram-negative bacteria in accordance with ISO 22196. Bacterial growth was significantly reduced for the MAAC-treated PVC, plasticized PVC, polyurethane and silicone (90–99.999%) in which antibacterial activity of ≥1 log reduction was reached for all bacterial strains tested. Cytotoxicity was evaluated following ISO 10993-5 guidelines and L929 cell viability was calculated at ≥90% in the presence of MAAC. This study demonstrates that the MAAC could prevent bacterial contamination as demonstrated by the ISO 22196 tests, while further work needs to be done to improve the coating processability and effectiveness of more complex matrices.

scholarly journals Viability of lactic acid bacteria in different components of Ogi with anti diarrhoeagenic E. coli activities

2019 ◽  
Vol 3 (6) ◽  
pp. 206-213
Author(s):  
Roseline Eleojo Kwasi ◽  
Iyanuoluwa Gladys Aremu ◽  
Qudus Olamide Dosunmu ◽  
Funmilola A. Ayeni
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Antimicrobial Properties ◽  
Culture Method ◽  
Antimicrobial Activities ◽  
Drying Methods ◽  
Bacterial Strains ◽  
E Coli ◽  
Log Reduction ◽  
Freeze Dried

Background: Ogi constitutes a rich source of lactic acid bacteria (LAB) with associated health benefits to humans through antimicrobial activities. However, the high viability of LAB in Ogi and its supernatant (Omidun) is essential. Aims: This study was carried out to assess the viability of LAB in various forms of modified and natural Ogi and the antimicrobial properties of Omidun against diarrhoeagenic E coli. Methods and Material: The viability of LAB was assessed in fermented Ogi slurry and Omidun for one month and also freeze-dried Ogi with and without added bacterial strains for two months. A further 10 days viability study of modified Omidun, refrigerated Omidun, and normal Ogi was performed. The antimicrobial effects of modified Omidun against five selected strains of diarrhoeagenic E. coli (DEC) were evaluated by the co-culture method. Results: Both drying methods significantly affected carotenoids and phenolic compounds. The Ogi slurry had viable LAB only for 10 days after which, there was a succession of fungi and yeast. Omidun showed 2 log10cfu/ml reduction of LAB count each week and the freeze-dried Ogi showed progressive reduction in viability. Refrigerated Omidun has little viable LAB, while higher viability was seen in modified Omidun (≥2 log cfu/ml) than normal Omidun. Modified Omidun intervention led to 2-4 log reduction in diarrhoeagenic E. coli strains and total inactivation of shigella-toxin producing E. coli H66D strain in co-culture. Conclusions: The consumption of Ogi should be within 10 days of milling using modified Omidun. There are practical potentials of consumption of Omidun in destroying E. coli strains implicated in diarrhea. Keywords: Ogi, Omidun, lactic acid bacteria, diarrhoeagenic Escherichia coli strains, Viability.

scholarly journals Evaluating the abilities of diverse nitroaromatic prodrug metabolites to exit a model Gram negative vector for bacterial-directed enzyme-prodrug therapy

2020 ◽  
Author(s):  
JVE Chan-Hyams ◽  
JN Copp ◽  
JB Smaill ◽  
AV Patterson ◽  
David Ackerley
Keyword(s):  
Human Cell ◽  
Bacterial Cell ◽  
Bystander Effect ◽  
Cell Transfer ◽  
Bacterial Strains ◽  
Enzyme Prodrug Therapy ◽  
E Coli ◽  
Human Cell Cultures ◽  
Cell To Cell Transfer ◽  
Nitro Reduction

© 2018 Elsevier Inc. Gene-directed enzyme-prodrug therapy (GDEPT) employs tumour-tropic vectors including viruses and bacteria to deliver a genetically-encoded prodrug-converting enzyme to the tumour environment, thereby sensitising the tumour to the prodrug. Nitroreductases, able to activate a range of promising nitroaromatic prodrugs to genotoxic metabolites, are of great interest for GDEPT. The bystander effect (cell-to-cell transfer of activated prodrug metabolites) has been quantified for some nitroaromatic prodrugs in mixed multilayer human cell cultures, however while these provide a good model for viral DEPT (VDEPT) they do not inform on the ability of these prodrug metabolites to exit bacterial vectors (relevant to bacterial-DEPT (BDEPT)). To investigate this we grew two Escherichia coli strains in co-culture; an activator strain expressing the nitroreductase E. coli NfsA and a recipient strain containing an SOS-GFP DNA damage responsive gene construct. In this system, induction of GFP by reduced prodrug metabolites can only occur following their transfer from the activator to the recipient cells. We used this to investigate five clinically relevant prodrugs: metronidazole, CB1954, nitro-CBI-DEI, and two dinitrobenzamide mustard prodrug analogues, PR-104A and SN27686. Consistent with the bystander efficiencies previously measured in human cell multilayers, reduced metronidazole exhibited little bacterial cell-to-cell transfer, whereas nitro-CBI-DEI was passed very efficiently from activator to recipient cells post-reduction. However, in contrast with observations in human cell multilayers, the nitrogen mustard prodrug metabolites were not effectively passed between the two bacterial strains, whereas reduced CB1954 was transferred efficiently. Using nitroreductase enzymes that exhibit different biases for the 2- versus 4-nitro substituents of CB1954, we further showed that the 2-nitro reduction products exhibit substantially higher levels of bacterial cell-to-cell transfer than the 4-nitro reduction products, consistent with their relative bystander efficiencies in human cell culture. Overall, our data suggest that prodrugs may differ in their suitability for VDEPT versus BDEPT applications and emphasise the importance of evaluating an enzyme-prodrug partnership in an appropriate context for the intended vector.

scholarly journals The key bacterial cell division protein FtsZ as a novel antibacterial drug target

2020 ◽  
Author(s):  
Mujeeb Rahman ◽  
Ping Wang ◽  
Na Wang ◽  
Yaodong Chen
Keyword(s):  
Cell Division ◽  
Bacterial Cell ◽  
Drug Targets ◽  
Multidrug Resistant ◽  
Antibacterial Drug ◽  
Bacterial Cell Division ◽  
Bacterial Strains ◽  
Antimicrobial Drugs ◽  
Novel Antibiotics

The number of multidrug-resistant bacterial strains is currently increasing; thus, the determination of drug targets for the development of novel antimicrobial drugs is urgently needed. FtsZ, the prokaryotic homolog of the eukaryotic tubulin, is a GTP-dependent prokaryotic cytoskeletal protein that is conserved among most bacterial strains. In vitro studies revealed that FtsZ self-assembles into dynamic protofilaments or bundles, and it forms a dynamic Z-ring at the center of the cell, leading to septation and consequent cell division. The potential role of FtsZ in the blockage of cell division makes FtsZ a highly attractive target for developing novel antibiotics. Researchers have been working on synthetic molecules and natural products as inhibitors of FtsZ. Accumulating data suggest that FtsZ may provide the platform for the development of novel antibiotics. In this review, we summarize recent advances on the properties of FtsZ protein and bacterial cell division, as well as on the development of FtsZ inhibitors.

scholarly journals Effects of natural antimicrobials on bacterial cell hydrophobicity, adhesion, and zeta potential / Vpliv naravnih protimikrobnih snovi na bakterijsko hidrofobnost, adhezijo in zeta potencial

2016 ◽  
Vol 67 (1) ◽  
pp. 39-45 ◽  
Author(s):  
Marija Kurinčič ◽  
Barbara Jeršek ◽  
Anja Klančnik ◽  
Sonja Smole Možina ◽  
Rok Fink ◽  
...  
Keyword(s):  
Zeta Potential ◽  
Bacterial Adhesion ◽  
Bacterial Cell ◽  
Early Stage ◽  
Experimental Studies ◽  
Adhesion Prevention ◽  
Bacterial Cells ◽  
Bacterial Strains ◽  
Natural Antimicrobials ◽  
Cell Hydrophobicity

Abstract Interactions between bacterial cells and contact materials play an important role in food safety and technology. As bacterial strains become ever more resistant to antibiotics, the aim of this study was to analyse adhesion of selected foodborne bacterial strains on polystyrene surface and to evaluate the effects of natural antimicrobials on bacterial cell hydrophobicity, adhesion, and zeta potential as strategies of adhesion prevention. The results showed strain-specific adhesion rate on polystyrene. The lowest and the highest adhesion were found for two B. cereus lines. Natural antimicrobials ferulic and rosmarinic acid substantially decreased adhesion, whereas the effect of epigallocatechin gallate was neglectful. Similar results were found for the zeta potential, indicating that natural antimicrobials reduce bacterial adhesion. Targeting bacterial adhesion using natural extracts we can eliminate potential infection at an early stage. Future experimental studies should focus on situations that are as close to industrial conditions as possible.

Inactivation of Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella in Cranberry, Lemon, and Lime Juice Concentrates

2003 ◽  
Vol 66 (9) ◽  
pp. 1637-1641 ◽  
Author(s):  
MARA C. L. NOGUEIRA ◽  
OMAR A. OYARZÁBAL ◽  
DAVID E. GOMBAS
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Pathogenic Bacteria ◽  
Antimicrobial Properties ◽  
Escherichia Coli O157 ◽  
Bacterial Inactivation ◽  
Lime Juice ◽  
E Coli ◽  
Log Reduction ◽  
C 32

The production of thermally concentrated fruit juices uses temperatures high enough to achieve at least a 5-log reduction of pathogenic bacteria that can occur in raw juice. However, the transportation and storage of concentrates at low temperatures prior to final packaging is a common practice in the juice industry and introduces a potential risk for postconcentration contamination with pathogenic bacteria. The present study was undertaken to evaluate the likelihood of Escherichia coli O157: H7, Listeria monocytogenes and Salmonella surviving in cranberry, lemon, and lime juice concentrates at or above temperatures commonly used for transportation or storage of these concentrates. This study demonstrates that cranberry, lemon, and lime juice concentrates possess intrinsic antimicrobial properties that will eliminate these bacterial pathogens in the event of postconcentration recontamination. Bacterial inactivation was demonstrated under all conditions; at least 5-log Salmonella inactivation was consistently demonstrated at −23°C (−10°F), at least 5-log E. coli O157:H7 inactivation was consistently demonstrated at −11°C (12°F), and at least 5-log L. monocytogenes inactivation was consistently demonstrated at 0°C (32°F).

scholarly journals Dramatic performance ofClostridium thermocellumexplained by its wide range of cellulase modalities

2016 ◽  
Vol 2 (2) ◽  
pp. e1501254 ◽  
Author(s):  
Qi Xu ◽  
Michael G. Resch ◽  
Kara Podkaminer ◽  
Shihui Yang ◽  
John O. Baker ◽  
...  
Keyword(s):  
Cell Wall ◽  
Bacterial Cell ◽  
Mode Of Action ◽  
Protein Complexes ◽  
Cellulose Degradation ◽  
Bacterial Cell Wall ◽  
Cellular Functions ◽  
Gene Deletions ◽  
Wide Range ◽  
Biomass Particles

Clostridium thermocellumis the most efficient microorganism for solubilizing lignocellulosic biomass known to date. Its high cellulose digestion capability is attributed to efficient cellulases consisting of both a free-enzyme system and a tethered cellulosomal system wherein carbohydrate active enzymes (CAZymes) are organized by primary and secondary scaffoldin proteins to generate large protein complexes attached to the bacterial cell wall. This study demonstrates thatC. thermocellumalso uses a type of cellulosomal system not bound to the bacterial cell wall, called the “cell-free” cellulosomal system. The cell-free cellulosome complex can be seen as a “long range cellulosome” because it can diffuse away from the cell and degrade polysaccharide substrates remotely from the bacterial cell. The contribution of these two types of cellulosomal systems inC. thermocellumwas elucidated by characterization of mutants with different combinations of scaffoldin gene deletions. The primary scaffoldin, CipA, was found to play the most important role in cellulose degradation byC. thermocellum, whereas the secondary scaffoldins have less important roles. Additionally, the distinct and efficient mode of action of theC. thermocellumexoproteome, wherein the cellulosomes splay or divide biomass particles, changes when either the primary or secondary scaffolds are removed, showing that the intact wild-type cellulosomal system is necessary for this essential mode of action. This new transcriptional and proteomic evidence shows that a functional primary scaffoldin plays a more important role compared to secondary scaffoldins in the proper regulation of CAZyme genes, cellodextrin transport, and other cellular functions.

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