UV-C inactivation of Escherichia coli at different temperatures

A Pandemia COVID-19, causada pelo vírus SARS-COV-2, evidenciou a necessidade de desenvolvimento de métodos seguros e economicamente viáveis para a realização de desinfecções em escala comercial e doméstica. Os coronavírus são mais suscetíveis à radiação UV-C do que fungos e bactérias e diversos estudos relacionados à eficiência da UVC contra o vírus causador da COVID-19 já foram realizados utilizando micro-organismos substitutos. Desta forma, este estudo buscou o desenvolvimento de um dispositivo acessível a usuários leigos para utilização em materiais que não podem ser submetidos a métodos convencionais de eliminação de micro-organismos (desinfecção química ou térmica). Esta pesquisa propôs a produção e validação de um dispositivo emissor de radiação UV-C portátil para a desinfeção de substratos suscetíveis a contaminação por bactérias, fungos e vírus patogênicos. O dispositivo foi desenvolvido a partir de materiais acessíveis a grande parte das empresas e população. Em seguida foi realizada a validação da eficiência do dispositivo através da exposição de culturas microbianas (bactéria Gram positiva, negativa e levedura) em diferentes intervalos de tempo. O dispositivo foi desenvolvido plenamente a partir de materiais de baixo custo e acessíveis. Todos os micro-organismos testados (Candida albicans, Staphylococcus aureus e Escherichia coli) foram eliminados do meio de cultura com menos de 20 min. de exposição. O dispositivo desenvolvido neste estudo pode ser construído por boa parte das empresas e população. O dispositivo se mostrou eficaz para reduzir o risco de contágio de diferentes micro-organismos patogênicos, sugerindo sua efetividade contra SARS- COV-2 causador da pandemia COVID-19.

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Adaptation of O157:H7 and non-O157 Escherichia coli strains in orange juice and subsequent resistance to UV-C radiation

LWT ◽

10.1016/j.lwt.2022.113107 ◽

2022 ◽

pp. 113107

Author(s):

Juan M. Oteiza ◽

Magdevis Y.R. Caturla ◽

Leonardo do Prado-Silva ◽

Antonio A. Câmara ◽

Patricia A. Barril ◽

...

Keyword(s):

Escherichia Coli ◽

Orange Juice ◽

Uv C

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Evaluation of the rate constants of sugar transport through maltoporin (LamB) of Escherichia coli from the sugar-induced current noise.

The Journal of General Physiology ◽

10.1085/jgp.105.3.385 ◽

1995 ◽

Vol 105 (3) ◽

pp. 385-401 ◽

Cited By ~ 53

Author(s):

C Andersen ◽

M Jordy ◽

R Benz

Keyword(s):

Escherichia Coli ◽

Binding Site ◽

Outer Membrane ◽

Rate Constants ◽

Sugar Transport ◽

Current Noise ◽

Induced Current ◽

Lipid Bilayer Membranes ◽

Sugar Binding ◽

Different Temperatures

LamB (maltoporin) of Escherichia coli outer membrane was reconstituted into artificial lipid bilayer membranes. The channel contains a binding site for sugars and is blocked for ions when the site is occupied by a sugar. The on and off reactions of sugar binding cause an increase of the noise of the current through the channel. The sugar-induced current noise of maltoporin was used for the evaluation of the sugar-binding kinetics for different sugars of the maltooligosaccharide series and for sucrose. The on rate constant for sugar binding was between 10(6) and 10(7) M-1.s-1 for the maltooligosaccharides and corresponds to the movement of the sugars from the aqueous phase to the central binding site. The off rate (corresponding to the release of the sugars from the channel) decreased with increasing number of glucose residues in the maltooligosaccharides from approximately 2,000 s-1 for maltotriose to 180 s-1 for maltoheptaose. The kinetics for sucrose movement was considerably slower. The activation energies of the stability constant and of the rate constants for sugar binding were evaluated from noise experiments at different temperatures. The role of LamB in the transport of maltooligosaccharides across the outer membrane is discussed.

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Optimization of Electrolysis Parameters for Green Sanitation Chemicals Production Using Response Surface Methodology

Processes ◽

10.3390/pr8070792 ◽

2020 ◽

Vol 8 (7) ◽

pp. 792

Author(s):

Nurul Izzah Khalid ◽

Nurul Shaqirah Sulaiman ◽

Norashikin Ab Aziz ◽

Farah Saleena Taip ◽

Shafreeza Sobri ◽

...

Keyword(s):

Escherichia Coli ◽

Food Industry ◽

Chemical Properties ◽

Bactericidal Effect ◽

Electrolyzed Water ◽

Optimum Parameters ◽

Physico Chemical ◽

Different Types ◽

Different Temperatures ◽

Optimized Conditions

Electrolyzed water (EW) shows great potential as a green and economical sanitation solution for the food industry. However, only limited studies have investigated the optimum electrolysis parameters and the bactericidal effect of acidic electrolyzed water (AcEW) and alkaline electrolyzed water (AlEW). Here, the Box–Behnken experimental design was used to identify the optimum parameters. The tests were conducted with different types of electrodes, electrical voltages, electrolysis times, and NaCl concentrations. There were no obvious differences observed in the physico-chemical properties of EW when different electrodes were used. However, stainless steel was chosen as it meets most of the selection criteria. The best-optimized conditions for AcEW were at 11.39 V, 0.65 wt.% NaCl, and 7.23 min, while the best-optimized conditions for AlEW were at 10.32 V, 0.6 wt.% NaCl, and 7.49 min. The performance of the optimum EW (AcEW and AlEW) compared with commercial cleaning detergents for the food industry was then evaluated. The bactericidal activity of AcEW and AlEW was examined against Escherichia coli ATCC 10536 at different temperatures (30 °C and 50 °C) for 30 s. The results show that both AcEW and AlEW have the ability to reduce the Escherichia coli to non-detectable levels (less than 2 log CFU/mL).

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