bacterial inactivation
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2022 ◽  
Vol 12 ◽  
Author(s):  
Shenmiao Li ◽  
Kelvin Ka-wan Chan ◽  
Marti Z. Hua ◽  
Greta Gölz ◽  
Xiaonan Lu

Campylobacter jejuni is a major bacterial cause of human diarrheal diseases worldwide. Despite its sensitivity to environmental stresses, C. jejuni ubiquitously distributes throughout poultry production chains. Biofilm formation mediated by quorum sensing is suggested to be critical to the survival of C. jejuni in agroecosystem. C. jejuni possesses LuxS, the enzyme involved in the production of autoinducer-2 (AI-2) signaling molecules. In this study, two fatty acids, namely decanoic acid and lauric acid, were identified to be effective in inhibiting AI-2 activity of C. jejuni. Both decanoic acid and lauric acid at 100 ppm inhibited ∼90% AI-2 activity (P < 0.05) of C. jejuni without bacterial inactivation. The biofilm biomass of two C. jejuni strains was reduced by 10–50% (P < 0.05) after treatment by both fatty acids, while increased biofilm formation was observed for one C. jejuni strain. In addition, both fatty acids effectively reduced the motility of all tested C. jejuni strains. These findings can aid in developing alternative C. jejuni control strategies in agri-food and clinical settings.


Author(s):  
Mokhamad Tirono ◽  
Farid Samsu Hananto ◽  
Ahmad Abtokhi

Background: Treatment of wounds in diabetes often gets less than perfect healing. One of the reasons for the difficulty in treating wounds in diabetes is the growth of aerobic and anaerobic bacteria. This study aims to determine the pulse voltage and treatment time that can optimally inactivate bacteria, and their effect on wound healing in mice suffering from diabetes. Methods: The study used electrical stimulation with a direct voltage of 10 volts given a pulse voltage of 50-80 volts, a width of 50 µs, and the number of pulses of 65 per second. The research samples were Staphylococcus aureus (S. aureus) and Pseudo-monas aeruginosa (P. aeruginosa) bacteria that grew on beef and mice (Mus musculus) with diabetes. The treatment for S. aureus and P. aeruginosa bacteria was carried out using a pulse voltage of 50-80 volts for 5-15 min/day and repeated for 3 days. Meanwhile, treatment of mice wounds was carried out with a pulse voltage of 80 volts for 15 min/day and repeated for 7 days. Results: The results showed that treatment with a pulse voltage of 50-80 volts and a treatment time of 5-15 min significantly reduced the number of S. aureus and P. aeruginosa bacteria in beef (p£0.05). Treatment with a pulse voltage of 80 volts for 15 min made beef free from bacteria. Meanwhile, treatment with a pulse voltage of 80 volts for 15 min per day for seven days resulted in the wound state of three mice in the maturation phase and two mice in the proliferation phase on day 8 with an average wound area of 0.108 cm 2. Conclusion: The treatment with a pulse voltage of 80 volts for 15 min made the beef sterile, the mice wounds healed quickly, and the mice not stressed. The higher the blood glucose level, the slower the wound healing process.  


2021 ◽  
Vol 10 (1) ◽  
pp. 40
Author(s):  
Karyne Rangel ◽  
Fellipe O. Cabral ◽  
Guilherme C. Lechuga ◽  
João P. R. S. Carvalho ◽  
Maria H. S. Villas-Bôas ◽  
...  

(1) Background: Disinfection of medical devices designed for clinical use associated or not with the growing area of tissue engineering is an urgent need. However, traditional disinfection methods are not always suitable for some biomaterials, especially those sensitive to chemical, thermal, or radiation. Therefore, the objective of this study was to evaluate the minimal concentration of ozone gas (O3) necessary to control and kill a set of sensitive or multi-resistant Gram-positive and Gram-negative bacteria. The cell viability, membrane permeability, and the levels of reactive intracellular oxygen (ROS) species were also investigated; (2) Material and Methods: Four standard strains and a clinical MDR strain were exposed to low doses of ozone at different concentrations and times. Bacterial inactivation (cultivability, membrane damage) was investigated using colony counts, resazurin as a metabolic indicator, and propidium iodide (PI). A fluorescent probe (H2DCFDA) was used for the ROS analyses; (3) Results: No reduction in the count colony was detected after O3 exposure compared to the control group. However, the cell viability of E. coli (30%), P. aeruginosa (25%), and A. baumannii (15%) was reduced considerably. The bacterial membrane of all strains was not affected by O3 but presented a significant increase of ROS in E. coli (90 ± 14%), P. aeruginosa (62.5 ± 19%), and A. baumanni (52.6 ± 5%); (4) Conclusion: Low doses of ozone were able to interfere in the cell viability of most strains studied, and although it does not cause damage to the bacterial membrane, increased levels of reactive ROS are responsible for causing a detrimental effect in the lipids, proteins, and DNA metabolism.


AMB Express ◽  
2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Soudabeh Ghodsi ◽  
Ali Esrafili ◽  
Hamid Reza Sobhi ◽  
Roshanak Rezaei Kalantary ◽  
Mitra Gholami ◽  
...  

AbstractContamination of water with bacteria is one of the main causes of waterborne diseases. The photocatalytic method on the basis of bacterial inactivation seems to be a suitable disinfectant due to the lack of by-products formation. Herein, g-C3N4/Fe3O4/Ag nanocomposite combined with UV-light irradiation was applied for the inactivation two well-known bacteria namely, E. coli and B. subtilis. The nanocomposite was prepared by a hydrothermal method, and subsequently it was characterized by XRD, FT-IR, SEM, EDX and PL analyses. The optimum conditions established for the inactivation of both bacteria were as follows: nanocomposite dosage 3 g/L and bacterial density of 103 CFU/mL. In the meantime, the efficient inactivation of E. coli and B. subtilis took 30 and 150 min, respectively. The results also revealed that inactivation rate dropped with an increase in the bacterial density. It is also pointed out that OH˚ was found out to be the main radical species involved in the inactivation process. Finally, the kinetic results indicated that the inactivation of E. coli and B. subtilis followed the Weibull model. It is concluded that C3N4/Fe3O4/Ag nanocomposite along with UV-light irradiation is highly effective in inactivating E. coli and B. subtilis bacteria in the aqueous solutions.


Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7341
Author(s):  
Lotfi Khezami ◽  
Imen Lounissi ◽  
Anouar Hajjaji ◽  
Ahlem Guesmi ◽  
Aymen Amine Assadi ◽  
...  

This work reports on the effect of TiO2 nanotubes (TiO2-NTs), decorated wih platinum nanoparticles (Pt-NPs), on the removal of bacteria and volatile organic compounds (VOCs). The Pt-NPs were loaded onto the TiO2-NTs using the electrodeposition method at four decoration times (100, 200, 300, and 600 s). The realized Pt-NPs/TiO2-NTs nanocomposites were used for the degradation of cyclohexane, a highly toxic and carcinogenic VOC pollutant in the chemical industry. The achieved Pt-NPs/TiO2-NTs nanocomposites were characterized using X-ray diffraction (XRD), photoluminescence (PL), diffuse reflectance spectroscopy (UV–Vis), and scanning (SEM) and transmission (TEM) electron microscopy. To understand the photocatalytic and antibacterial behavior of the Pt-NPs/TiO2-NTs, simultaneous treatment of Escherichia coli and cyclohexane was conducted while varying the catalyst time decoration. We noticed a complete bacterial inactivation rate with 90% VOC removal within 60 min of visible light irradiation. Moreover, the Langmuir–Hinshelwood model correlated well with the experimental results of the photocatalytic treatment of indoor air.


2021 ◽  
Vol 11 (23) ◽  
pp. 11281
Author(s):  
Aivaras Šalaševičius ◽  
Dovilė Uždavinytė ◽  
Mindaugas Visockis ◽  
Paulius Ruzgys ◽  
Saulius Šatkauskas

There is growing concern regarding the nutritional value of processed food products. Although thermal pasteurization, used in food processing, is a safe method and is widely applied in the food industry, food products lack quality and nutritional value because of the high temperatures used during pasteurization. In this study, the effect of pulsed electric field (PEF) processing on whey protein content and bacterial viability in raw milk was evaluated by changing the PEF strength and number of pulses. For comparison, traditional pasteurization techniques, such as low-temperature long-time (LTLT), ultra-high temperature (UHT), and microfiltration (MF), were also tested for total whey protein content, bacterial activity, and coliforms. We found that, after treatment with PEF, a significant decrease in total bacterial viability of 2.43 log and coliforms of 0.9 log was achieved, although undenatured whey protein content was not affected at 4.98 mg/mL. While traditional pasteurization techniques showed total bacterial inactivation, they were detrimental for whey protein content: β-lactoglobulin was not detected using HPLC in samples treated with UHT. LTLT treatment led to a significant decrease of 75% in β-lactoglobulin concentration; β-lactoglobulin content in milk samples treated with MF was the lowest compared to LTLT and UHT pasteurization, and ~10% and 27% reduction was observed.


Plasma ◽  
2021 ◽  
Vol 4 (4) ◽  
pp. 755-763
Author(s):  
Alvin D. Ngo ◽  
Kedar Pai ◽  
Christopher Timmons ◽  
Li Maria Ma ◽  
Jamey Jacob

Surface dielectric barrier discharge (SDBD) was used to evaluate cylindrical plasma actuators for inactivation of Salmonella enterica. A cylindrical SDBD configuration was evaluated to determine if the inherent induced body force could be leveraged to impel plasma species, such as reactive oxygen and nitrogen species (RONS), as an apparatus to sterilize surfaces. The cylindrical structure is evaluated in this study to observe whether an increase in mixing is possible to efficiently distribute the plasma species, thereby improving bacterial inactivation efficiency. The increase in induced airflow of SDBD actuators with increased numbers of electrodes correlates with increased bacterial inactivation. These results suggest that improving the particle velocity, airflow mixing tendencies, and plasma volume for the same power inputs (same net power to the actuators) results in increased surface decontamination efficiency.


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