Navegando por Assunto "Escherichia coli"

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Acesso aberto (Open Access)
Efeito da temperatura e molaridade na avaliação das atividades antimicrobiana, citotóxica e antioxidante do bio-óleo da semente do açaí (Euterpe oleracea, Mart.)
(Universidade Federal do Pará, 2024-08) SILVA, Iago Castro da; MACHADO, Nélio Teixeira; http://lattes.cnpq.br/5698208558551065; MONTEIRO, Marta Chagas; http://lattes.cnpq.br/6710783324317390; https://orcid.org/0000-0002-3328-5650
Açaí, a fruit from the Amazon, is valuable both economically and nutritionally. Its seeds, which are typically discarded, can be converted into bio-oil through pyrolysis (a process of thermochemical degradation of residual biomass), offering a sustainable alternative to fossil fuels. This study explores how temperature and molarity with Potassium Hydroxide (KOH) and Hydrochloric Acid (HCl), which are chemical impregnation reagents in the process, affect the antimicrobial, antioxidant, and cytotoxic activities of the produced bio-oil. Tests were conducted using Gas Chromatography coupled with Mass Spectrometry (GC-MS) and assays to evaluate antimicrobial, antioxidant, and cytotoxic activities at different temperatures (350, 400, and 450 °C) and molarities (0.5 M, 1.0 M, and 2.0 M). Phenolic compounds were the most abundant in the bio-oil (55.70%), followed by cyclic and aromatic hydrocarbons (11.89%) and linear hydrocarbons (9.64%). Despite a reduction in oxygenated compounds, the bio-oil retained bacteriostatic activity against Escherichia coli and Staphylococcus aureus across various temperature ranges, with notable effectiveness at 350 °C. Antioxidant activity was highest at 350 °C and at lower molarities. Furthermore, lower concentrations of acidic impregnation exhibited cytotoxic effects at high temperatures. Thus, bio-oil from açaí seeds generated through pyrolysis shows potential for antioxidant and antimicrobial activities, suggesting feasibility for further testing in dilutions with lower cytotoxicity.
Acesso aberto (Open Access)
Estudo teórico do complexo cefoxitina-proteína 5 de ligação à penicilina da Escherichia Coli por dinâmica molecular com método híbrido de mecânica quântica/ mecânica molecular
(Universidade Federal do Pará, 2014-12-12) SILVA, Thaís Boulhosa Barros da; BARROS, Carlos Augusto Lima; http://lattes.cnpq.br/8902921733540173; MONTEIRO, Marta Chagas; http://lattes.cnpq.br/6710783324317390
The Penicillin Binding Proteins (PBPs) are important for the development of new drugs against bacterial infections biological targets. This study was aimed to understand the interaction between the protein and cefoxitin 5 Penicillin-Binding (PBP5) of Escherichia coli (deposited in the PDB under the code 3MZE) through simulation Molecular Dynamics (MD), using the approach hybrid quantum molecular mechanics (QM/MM) and mechanical. As well as develop a prototype to evaluate, through computer simulation, the susceptibility of Gram negative bacteria against antibiotics. The analysis of antimicrobial susceptibility to antibiotics tested has shown that this strain of E. coli ATCC 8739 was sensitive to 5 antimicrobials study. The strain of E. coli derived from the clinical isolate was resistant to ciprofloxacin 5 μg and gentamicin 10 μg, intermediate sensitivity to cefepime 30 μg and ceftazidime 30 μg, and sensitivity to cefoxitina 30 μg. The difference in susceptibility of E. coli strain ATCC 8739 and strain of E. coli isolated from a clinical can show a molecular immunological memory of the bacteria. We observed no production of β-lactamases by the strain of E. coli derived from clinical isolate, suggested because no observed difference in antimicrobial susceptibility with respect to the presence or absence of EDTA on the disks containing the antibiotics. The analysis has revealed that protonation of the deprotonated His146, His151, His216 and His320 residues. The stabilization of the complex was studied after 0,6 ns of MD simulation. Moreover, a decomposition analysis in terms of energy was performed to determine the contributions of individual amino acid residues for protein-ligand interactions. The results revealed that cefoxitin has a strong interaction with Lis44, Lis210, Ser41, Gli212, His213, Glu246 residue, apart from water, which are important for stabilizing cefoxitin-PBP5 complex. The electrostatic potential map Molecular cefoxitin revealed a highly electrophilic center corresponding to the β-lactam ring, which promotes hydroxyl attack nuceofílico the serine residue of the E. coli PBP5 active site region. These results can give support the planning of new more selective and effective drugs to control bacterial infections. The experimental results were statistically consistent with the theoretical results thus this work can be used as a prototype for computing theoretical evaluate the antimicrobial susceptibility to Gram negative bacteria. This study may find applications in future planning and development of new and potent compounds with antimicrobial activity. Mainly in attempts to modify an inhibitor, particularly of the cephalosporin class in order to improve its selectivity and its activity.
Desconhecido
Sanitary quality of the public groundwater supply for the municipality of Belém in northern Brazil
(2013) OLIVEIRA, Rodrigo Santos de; KIYATAKE, Daniela Mayumi; HARADA, Maria Lúcia; RIBEIRO, Karla Tereza Silva
The present study verified the quality of the water of Água Preta Lake, which is part of the public supply for the Northern Brazilian municipality of Belém (Pará State). Six samples were collected from each of six sampling points. The concentration (NMP) of coliforms was determined by Multiple-tube fermentation Technique. The isolates of Escherichia coli obtained from the samples were tested for susceptibility to the antibiotics (cefoxitin, ampicillin, imipenem, gentamicin, and amikacin). Furthermore, was analyzed the presence of diagnostic genes for the diarrheagenic strains of E. coli. None of the genes was identified, however, the recorded concentrations of thermo-tolerant coliforms were within the recommended limits for standing water sources used for public supplies. Nevertheless, the highest concentrations of total and thermo-tolerant coliforms were recorded at two points, one adjacent to the most densely-populated area of the lake margin, and the other near the catchment area for water from the Guamá River. The susceptibility testing indicated the presence of six resistance phenotype profiles, including multi-resistant strains. The results of the study reinforce the need for the systematic monitoring of this water source, in order to provide guidelines for the development of effective management policies for public water supplies, as well as the prevention of water-borne diseases.