scholarly journals Variability of Amyloid Propensity in Imperfect Repeats of CsgA Protein of Salmonella enterica and Escherichia coli

2021 ◽  
Vol 22 (10) ◽  
pp. 5127
Author(s):  
Natalia Szulc ◽  
Marlena Gąsior-Głogowska ◽  
Jakub W. Wojciechowski ◽  
Monika Szefczyk ◽  
Andrzej M. Żak ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Salmonella Enterica ◽  
Bacterial Biofilm ◽  
Bacterial Biofilms ◽  
Amino Acid Residues ◽  
Transmission Electron ◽  
Ft Raman Spectroscopy ◽  
Functional Amyloids ◽  
Self Aggregation ◽  
Ft Raman

CsgA is an aggregating protein from bacterial biofilms, representing a class of functional amyloids. Its amyloid propensity is defined by five fragments (R1–R5) of the sequence, representing non-perfect repeats. Gate-keeper amino acid residues, specific to each fragment, define the fragment’s propensity for self-aggregation and aggregating characteristics of the whole protein. We study the self-aggregation and secondary structures of the repeat fragments of Salmonella enterica and Escherichia coli and comparatively analyze their potential effects on these proteins in a bacterial biofilm. Using bioinformatics predictors, ATR-FTIR and FT-Raman spectroscopy techniques, circular dichroism, and transmission electron microscopy, we confirmed self-aggregation of R1, R3, R5 fragments, as previously reported for Escherichia coli, however, with different temporal characteristics for each species. We also observed aggregation propensities of R4 fragment of Salmonella enterica that is different than that of Escherichia coli. Our studies showed that amyloid structures of CsgA repeats are more easily formed and more durable in Salmonella enterica than those in Escherichia coli.

Evolution of microstructure during the thermal processing of titania and vanadium-modified titania gels

2003 ◽  
Vol 18 (3) ◽  
pp. 594-603 ◽  
Author(s):  
Francis J. Allison ◽  
David M. Grant ◽  
Karen McKinlay ◽  
Craig Bailey ◽  
Philip G. Harrison
Keyword(s):  
High Temperatures ◽  
Sol Gel ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Ft Raman Spectroscopy ◽  
Evolution Of Microstructure ◽  
Hydrolysis Of ◽  
Ft Raman

Sol-gel materials of TiO2 and vanadium-modified TiO2 of nominal composition 4, 8, and 16 wt.% vanadium were prepared by evaporation of aqueous colloidal sols obtained by the hydrolysis of aqueous solutions of titanium(IV) chloride with the appropriate amount of vanadyl oxalate using aqueous ammonia followed by peptization of the resulting hydrated solids using nitric acid. The nature of the sol-gel materials and their behavior on calcinations at temperatures up to 1273 K were investigated using x-ray fluorescence, powder x-ray diffraction, transmission electron microscopy, and electron diffraction and FT-Raman spectroscopy. At 333 K, all the gels comprised small (about 5 ± 1 nm) particles of anatase together with traces of brookite. The particle size changed little on thermal treatment at 573 K, but increased significantly at higher temperatures and was accompanied by transformation to rutile. Incorporation of vanadium in the gels reduced the temperature at which rutile began to appear from 923 K in pure TiO2 to 773 K in the V/TiO2 gels. Only rutile was present at high temperatures, except for the 16 V/TiO2 gel, when small amounts of phase-separated vanadia were also observed. A 2–3% substitutional incorporation of V4+ ions in the tetragonal rutile lattice occurred at high temperatures, but the majority of the vanadium was present in an amorphous, highly dispersed fashion.

EFECTO INHIBITORIO DE EXTRACTOS DE Vitex mollis Kunth CONTRA BACTERIAS Y ESPECIES DE Fusarium DE IMPORTANCIA HUMANA Y AGRÍCOLA

2018 ◽  
Vol 41 (4) ◽  
pp. 353-363
Author(s):  
Alberto J. Valencia-Botin ◽  
Melesio Gutiérrez-Lomelí ◽  
Juan A. Morales-Del-Río ◽  
Pedro J. Guerrero-Medina ◽  
Miguel A. Robles-García ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Salmonella Enterica ◽  
Micrococcus Luteus ◽  
E Coli

Actualmente existe la necesidad de hacer frente al problema de la resistencia a los antibióticos y al uso indiscriminado de fungicidas químicos en la agricultura. El objetivo de este trabajo fue evaluar el efecto inhibitorio de extractos acuosos, metanólicos, acetónicos y hexánicos de hoja y tallo de Vitex mollis Kunth (Lamiaceae) contra diferentes bacterias (Escherichia coli, Micrococcus luteus, Salmonella enterica y Staphylococcus aureus) y especies del hongo Fusarium (F. verticillioides, F. oxysporum, F. tapsinum y F. oxysporum f.sp. lycopersici) de importancia en la salud y en la agricultura, así como determinar su composición química general. Se determinaron las concentraciones inhibitorias mínimas (CIM) de todos los extractos por la técnica de microdilución, excepto del hexánico, que no presentó inhibición en las bacterias estudiadas. S. enterica fue la bacteria que mostró mayor sensibilidad al extracto metanólico de tallo (CIM = 28 μg mL-1), le siguieron M. luteus (CIM = 32 μg mL-1), S. aureus (CIM = 75 μg mL-1) y E. coli (CIM = 80 μg mL- 1). Los extractos metanólicos y acuosos de tallo presentaron mayor porcentaje de inhibición contra los diferentes tipos de Fusarium evaluados por el método de dilución en agar. Los extractos de V. mollis inhibieron a F. verticillioides entre 62 y 91 % con 120 μg mL-1 de extracto. El orden de las especies de hongos inhibidas por los extractos fue: F. verticillioides > F. oxysporum > F. tapsinum > F. oxysporum f.sp. lycopersici. La composición química de las especies se determinó mediante pruebas para fenoles, taninos, flavonoides, triterpenos, alcaloides, cumarinas y saponinas. Ninguno de los extractos presentó alcaloides y saponinas. Los fenoles (37.1 mg EAG/g muestra seca) y flavonoides (26.8 mg EQ/g muestra seca) fueron los compuestos mayoritarios en los extractos metanólicos y acuosos. En conclusión, se requieren cantidades muy pequeñas de extracto para la inhibición de bacterias y de Fusarium; por lo tanto, V. mollis puede ser considerada una fuente de metabolitos para este fin y en la agricultura como control alternativo dentro de un manejo integrado de enfermedades.

scholarly journals Biofilm Lithography enables high-resolution cell patterning via optogenetic adhesin expression

2018 ◽  
Vol 115 (14) ◽  
pp. 3698-3703 ◽  
Author(s):  
Xiaofan Jin ◽  
Ingmar H. Riedel-Kruse
Keyword(s):  
Escherichia Coli ◽  
Cell Patterning ◽  
Biophysical Model ◽  
Microbial Consortia ◽  
Bacterial Biofilms ◽  
Surface Pretreatment ◽  
Resolution Cell ◽  
Stimulation Of

Bacterial biofilms represent a promising opportunity for engineering of microbial communities. However, our ability to control spatial structure in biofilms remains limited. Here we engineerEscherichia coliwith a light-activated transcriptional promoter (pDawn) to optically regulate expression of an adhesin gene (Ag43). When illuminated with patterned blue light, long-term viable biofilms with spatial resolution down to 25 μm can be formed on a variety of substrates and inside enclosed culture chambers without the need for surface pretreatment. A biophysical model suggests that the patterning mechanism involves stimulation of transiently surface-adsorbed cells, lending evidence to a previously proposed role of adhesin expression during natural biofilm maturation. Overall, this tool—termed “Biofilm Lithography”—has distinct advantages over existing cell-depositing/patterning methods and provides the ability to grow structured biofilms, with applications toward an improved understanding of natural biofilm communities, as well as the engineering of living biomaterials and bottom–up approaches to microbial consortia design.

scholarly journals Inhibition of Escherichia coli O157:H7 and Salmonella enterica Isolates on Spinach Leaf Surfaces Using Eugenol-Loaded Surfactant Micelles

Foods ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 575
Author(s):  
Songsirin Ruengvisesh ◽  
Chris R. Kerth ◽  
T. Matthew Taylor
Keyword(s):  
Escherichia Coli ◽  
Salmonella Enterica ◽  
Limit Of Detection ◽  
Sodium Dodecyl ◽  
Microbial Pathogens ◽  
Escherichia Coli O157 ◽  
Human Pathogens ◽  
Surfactant Micelles ◽  
Leaf Surfaces ◽  
Spinach Leaf

Spinach and other leafy green vegetables have been linked to foodborne disease outbreaks of Escherichia coli O157:H7 and Salmonella enterica around the globe. In this study, the antimicrobial activities of surfactant micelles formed from the anionic surfactant sodium dodecyl sulfate (SDS), SDS micelle-loaded eugenol (1.0% eugenol), 1.0% free eugenol, 200 ppm free chlorine, and sterile water were tested against the human pathogens E. coli O157:H7 and Salmonella Saintpaul, and naturally occurring microorganisms, on spinach leaf surfaces during storage at 5 °C over 10 days. Spinach samples were immersed in antimicrobial treatment solution for 2.0 min at 25 °C, after which treatment solutions were drained off and samples were either subjected to analysis or prepared for refrigerated storage. Whereas empty SDS micelles produced moderate reductions in counts of both pathogens (2.1–3.2 log10 CFU/cm2), free and micelle-entrapped eugenol treatments reduced pathogens by >5.0 log10 CFU/cm2 to below the limit of detection (<0.5 log10 CFU/cm2). Micelle-loaded eugenol produced the greatest numerical reductions in naturally contaminating aerobic bacteria, Enterobacteriaceae, and fungi, though these reductions did not differ statistically from reductions achieved by un-encapsulated eugenol and 200 ppm chlorine. Micelles-loaded eugenol could be used as a novel antimicrobial technology to decontaminate fresh spinach from microbial pathogens.

scholarly journals Influence of Bacterial Competitors on Salmonella enterica and Enterohemorrhagic Escherichia coli Growth in Microbiological Media and Attachment to Vegetable Seeds

Foods ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 285
Author(s):  
Da Liu ◽  
Ronald Walcott ◽  
Kevin Mis Solval ◽  
Jinru Chen
Keyword(s):  
Escherichia Coli ◽  
Foodborne Pathogens ◽  
Salmonella Enterica ◽  
Lactobacillus Rhamnosus ◽  
Probiotic Bacterium ◽  
Enterohemorrhagic Escherichia Coli ◽  
Biocontrol Agents ◽  
Human Pathogens ◽  
Bacterial Strains ◽  
Pathogen Populations

Interests in using biological agents for control of human pathogens on vegetable seeds are rising. This study evaluated whether probiotic bacterium Lactobacillus rhamnosus GG, bacterial strains previously used as biocontrol agents in plant science, as well as a selected plant pathogen could compete with foodborne human pathogens, such as Salmonella enterica and enterohemorrhagic Escherichia coli (EHEC), for growth in microbiological media and attachment to vegetable seeds; and to determine whether the metabolites in cell-free supernatants of competitive bacterial spent cultures could inhibit the growth of the two pathogens. The results suggest that the co-presence of competitive bacteria, especially L. rhamnosus GG, significantly (p < 0.05) inhibited the growth of Salmonella and EHEC. Cell-free supernatants of L. rhamnosus GG cultures significantly reduced the pathogen populations in microbiological media. Although not as effective as L. rhamnosus GG in inhibiting the growth of Salmonella and EHEC, the biocontrol agents were more effective in competing for attachment to vegetable seeds. The study observed the inhibition of human bacterial pathogens by competitive bacteria or their metabolites and the competitive attachment to sprout seeds among all bacteria involved. The results will help strategize interventions to produce vegetable seeds and seed sprouts free of foodborne pathogens.

scholarly journals Factors associated with Salmonella enterica and Escherichia coli during downtime in commercial broiler chicken barns in Ontario

2021 ◽  
Vol 100 (5) ◽  
pp. 101065
Author(s):  
Chelsea E. Course ◽  
Patrick Boerlin ◽  
Durda Slavic ◽  
Jean-Pierre Vaillancourt ◽  
Michele T. Guerin
Keyword(s):  
Escherichia Coli ◽  
Salmonella Enterica ◽  
Broiler Chicken ◽  
Factors Associated ◽  
Commercial Broiler
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