Search results for "Coccus"
showing 10 items of 1002 documents
Bacterial growth and biological properties of Cymbopogon schoenanthus and Ziziphus lotus are modulated by extraction conditions
2020
Abstract The present study aims to evaluate the antibacterial activity and biological properties of two traditional Saharian plants (Cymbopogon schoenanthus and Ziziphus lotus). The plant extracts were obtained by using a different combination of extraction methods (conventional vs. ultrasound-assisted) and solvents (water vs. ethanol:water (50:50, v/v)). The antioxidant profile, anti-inflammatory activity and impact on bacterial growth (foodborne and probiotic bacteria) of the obtained extracts were assessed. The plant species showed the hierarchically more important role in determining the biological properties of the extracts, followed by extraction solvent and extraction conditions. Con…
Characterization of antimicrobial properties on the growth of S. aureus of novel renewable blends of gliadins and chitosan of interest in food packag…
2007
The biocide properties of chitosan-based materials have been known for many years. However, typical antimicrobial formulations of chitosan, mostly chitosonium salts, are known to be very water sensitive materials which may impair their use in many application fields such as food packaging or food coating applications. This first work reports on the development and characterization of the antimicrobial properties of novel fully renewable blends of chitosan with more water-resistant gliadin proteins isolated from wheat gluten. Chitosan release to the nutrient broth from a wide range of blends was studied making use of the ninhydrin method. The results indicated that both pure chitosan and its…
Thickness measurement of soft thin films on periodically patterned magnetic substrates by phase difference magnetic force microscopy
2013
The need for accurate measurement of the thickness of soft thin films is continuously encouraging the development of techniques suitable for this purpose. We propose a method through which the thickness of the film is deduced from the quantitative measurement of the contrast in the phase images of the sample surface acquired by magnetic force microscopy, provided that the film is deposited on a periodically patterned magnetic substrate. The technique is demonstrated by means of magnetic substrates obtained from standard floppy disks. Colonies of Staphylococcus aureus adherent to such substrates were used to obtain soft layers with limited lateral (a levy microns) and vertical (hundreds of n…
Alpha-toxin of Staphylococcus aureus
1991
Alpha-toxin, the major cytotoxic agent elaborated by Staphylococcus aureus, was the first bacterial exotoxin to be identified as a pore former. The protein is secreted as a single-chain, water-soluble molecule of Mr 33,000. At low concentrations (less than 100 nM), the toxin binds to as yet unidentified, high-affinity acceptor sites that have been detected on a variety of cells including rabbit erythrocytes, human platelets, monocytes and endothelial cells. At high concentrations, the toxin additionally binds via nonspecific absorption to lipid bilayers; it can thus damage both cells lacking significant numbers of the acceptor and protein-free artificial lipid bilayers. Membrane damage occu…
Pyrrolomycins as antimicrobial agents. Microwave-assisted organic synthesis and insights into their antimicrobial mechanism of action
2019
Abstract New compounds able to counteract staphylococcal biofilm formation are needed. In this study we investigate the mechanism of action of pyrrolomycins, whose potential as antimicrobial agents has been demonstrated. We performed a new efficient and easy method to use microwave organic synthesis suitable for obtaining pyrrolomycins in good yields and in suitable amount for their in vitro in-depth investigation. We evaluate the inhibitory activity towards Sortase A (SrtA), a transpeptidase responsible for covalent anchoring in Gram-positive peptidoglycan of many surface proteins involved in adhesion and in biofilm formation. All compounds show a good inhibitory activity toward SrtA, havi…
Discovery and structure-activity relationship studies of irreversible benzisothiazolinone-based inhibitors against Staphylococcus aureus sortase A tr…
2014
Gram-positive bacteria, in general, and staphylococci, in particular, are the widespread cause of nosocomial and community-acquired infections. The rapid evolvement of strains resistant to antibiotics currently in use is a serious challenge. Novel antimicrobial compounds have to be developed to fight these resistant bacteria, and sortase A, a bacterial cell wall enzyme, is a promising target for novel therapies. As a transpeptidase that covalently attaches various virulence factors to the cell surface, this enzyme plays a crucial role in the ability of bacteria to invade the host's tissues and to escape the immune response. In this study we have screened a small molecule library against rec…
Elimination of a bacterial pore-forming toxin by sequential endocytosis and exocytosis
2008
Staphylococcus aureus alpha-toxin is the archetype of bacterial pore forming toxins and a key virulence factor secreted by the majority of clinical isolates of S. aureus. Toxin monomers bind to target cells and oligomerize to form small beta-barrel pores in the plasma membrane. Many nucleated cells are able to repair a limited number of lesions by unknown, calcium-independent mechanisms. Here we show that cells can internalize alpha-toxin, that uptake is essential for cellular survival, and that pore-complexes are not proteolytically degraded, but returned to the extracellular milieu in the context of exosome-like structures, which we term toxosomes.
Bacterial 2,3-butanediol dehydrogenases
1978
Enterobacter aerogenes, Aeromonas hydrophila, Serratia marcescens and Staphylococcus aureus possessing L(+)-butanediol dehydrogenase produced mainly meso-butanediol and small amounts of optically active butanediol; Acetobacter suboxydans, Bacillus polymyxa and Erwinia carotovora containing D(-)-butanediol dehydrogenase produced more optically active butanediol than meso-butanediol. Resting and growing cells of these organisms oxidezed only one enantiomer of racemic butanediol. The D(-)-butanediol dehydrogenase from Bacillus polymyxa was partially purified (30-fold) with a specific activity of 24.5. Except NAD and NADH no other cofactors were required. Optimum pH-values for oxidation and red…
Staphylococcus aureus virulences faktoru un antibakteriālās rezistences noteikšana
2019
Staphylococcus aureus ir viena no izplatītākajām patogēnajām, gram pozitīvajām baktērijām, kas pateicoties tās virulences faktoriem, tādiem kā toksīniem, enzīmiem un struktūras komponentiem, spēj novājināt organisma imūno atbildi. Tādā veidā veicinot dažādu veselības traucējumu, it īpaši hospitālo infekciju un slimību attīstību. Mūsdienās, lielākoties visā pasaulē, it īpaši Dienvideiropā ir vērojama krasa MRSA izplatības palielināšanās, kas tiek nodrošināta pateicoties S. aureus sastāvā esošajam SCC mec u.c. ģenētiskajiem elementiem. Tādējādi panākot plaša spektra β-laktāma u.c. antibiotiku rezistences veidošanos, kas ar laiku var samazināt medikamentozās terapijas efektivitāti. Darba mērķi…
Report of toxic shock syndrome toxin 1 (TSST-1) from Staphylococcus aureus isolated in food handlers and surfaces from foodservice establishments.
2012
A set of 53 Staphylococcus aureus isolates collected from food handlers and foodservice establishments in Spain was analyzed for toxic shock syndrome toxin (TSST-1) production. S. aureus strains were isolated from 908 samples collected from different surfaces such as dish towels, workers’ hands, cutting boards, stainless steel tables and slicers, but they were not detected neither in clean plates nor in kitchen knives. Only one food worker hand has been reported to be contaminated by TSST-1 in a restaurant. Despite this, proper hygiene practices should be respected for the surfaces of contact with food, as well as for the hands of the manipulators This is the first article, in Spain, that r…