Search results for "bacteria."
showing 10 items of 4757 documents
Siderophore production by environmental strains ofSalmonellaspecies
1989
Iron uptake mechanisms were investigated in different species of Salmonella isolated from environmental waters. All strains examined were able to grow in the presence of high concentrations (10 mM) of the iron chelator EDDA. All strains excreted phenolate and hydroxamate siderophores, as assessed by bioassays and chemical tests. Bioassays with different indicator strains showed that all Salmonella strains can cross-feed other Enterobacteria, as well as mutants of Salmonella typhimurium deficient in the Enterobactin system, suggesting that this siderophore may be produced by the environmental Salmonella strains. The siderophore aerobactin may also be produced by one of the strains, according…
Evaluation of silver-infused polylactide films for inactivation of Salmonella and feline calicivirus in vitro and on fresh-cut vegetables
2012
There is a growing trend to develop packaging materials with an active role in guarantying that the quality and safety characteristics of packaged products will remain or improve from preparation throughout shelf-life. In the present study, 0.001-1.0 wt.% silver ions were satisfactorily incorporated into polylactide (PLA) films by a solvent casting technique. Silver migration from the films was measured by voltamperometry and then correlated with its antimicrobial efficacy against Salmonella enterica and feline calicivirus (FCV), a human norovirus surrogate, by using the Japanese industrial standard (JIS Z 2801). The PLA-silver films showed strong antibacterial and antiviral activity in vit…
Effects of chitosan films on the growth of Listeria monocytogenes, Staphylococcus aureus and Salmonella spp. in laboratory media and in fish soup.
2009
The objective of this study was to assess the antimicrobial effectiveness of chitosonium acetate films on the growth of Listeria monocytogenes, Salmonella spp. and Staphylococcus aureus. The samples were tested in both laboratory conditions using Tryptone Soy Broth (TSB) and in a real food system using fish soup. The study was carried out at different temperatures (4, 12, and 37 degrees C) in order to discern the influence of such variables. Moreover, a sensory evaluation of the final product was performed as a parameter of consumer acceptance. The results showed a significant reduction of the bacterial growth, which greatly depended on the bacteria type, the temperature of incubation and t…
Long-term survival of pathogenic and sanitation indicator bacteria in experimental biowaste composts
2005
ABSTRACT For economic, agricultural, and environmental reasons, composting is frequently used for organic waste recycling. One approach to limiting the potential risk from bacterial food-borne illnesses is to ensure that soil amendments and organic fertilizers are disinfected. However, more knowledge concerning the microbiological safety of composted substrates other than sludge and manure is necessary. Experimental in-vessel biowaste composts were used to study the survival of seeded Listeria monocytogenes , Salmonella enterica subsp. enterica serotype Enteritidis, and Escherichia coli . Four organic waste mixtures, containing various proportions of paper and cardboard, fruits and vegetabl…
Assessment of the microbiological quality and wash treatments of lettuce served in University restaurants
2000
Abstract One hundred and forty-four samples of lettuce from 16 University restaurants were analyzed. The mesophilic aerobic counts of all samples ranged from 3.01 to 7.81 log 10 CFU g −1 . Results of total coliforms ranged from 3.38 log 10 most probable number (MPN) g −1 . Of the lettuce samples, 25.7% harbored Escherichia coli , 22.9% Staphylococcus aureus and 84% group D streptococci. Similarly, 10.4% of the samples harbored Aeromonas hydrophila , 2.8% Pseudomonas aeruginosa , and coliforms such as 14.6% Citrobacter freundii , 8.3% Klebsiella pneumoniae , 4.2% Enterobacter cloacae and 1.4% Providencia spp. Salmonella , Shigella and E. coli O157:H7 were not detected. When sodium hypochlori…
Microbial characterisation of fermented meat productions from the Sicilian breed "Suino Nero dei Nebrodi"
2012
Two traditional sausage products (“salsiccia” and “salame”) processed from the raw meat of the Black Sicilian swine “Suino Nero dei Nebrodi” were microbiologically investigated during the manufacturing and ripening stages. Both products were dominated by lactic acid bacteria (LAB), especially rod-shaped types. The concentration of enterococci was consistent in salame. Coagulase-negative cocci increased slower than LAB. Yeasts showed an increasing trend during the ripening of both products. Enterobacteriaceae were counted at a constant level of about 105 CFU/g in both products, while pseudomonads diminished during ripening. Coagulase-positive staphylococci, Listeria monocytogenes and Salmone…
Quantitative detection of viable foodborne E. coli O157:H7, Listeria monocytogenes and Salmonella in fresh-cut vegetables combining propidium monoazi…
2012
Abstract The increase of foodborne outbreaks associated with fresh vegetables has highlighted the importance of developing rapid and specific methods for the detection and quantification of foodborne pathogens. In this sense, real-time PCR (qPCR) fulfills these requirements although it may detect dead cells. Recently, a potential strategy to specifically detect viable cells has been proposed relying on the use of DNA binding molecules as sample pretreatment previous to the qPCR. In this study propidium monoazide (PMA) and reagent D, combined with qPCR, were evaluated for the detection and quantification of viable Escherichia coli O157:H7, Salmonella and Listeria monocytogenes. Initially, th…
Salmonella bongori Provides Insights into the Evolution of the Salmonellae
2011
The genus Salmonella contains two species, S. bongori and S. enterica. Compared to the well-studied S. enterica there is a marked lack of information regarding the genetic makeup and diversity of S. bongori. S. bongori has been found predominantly associated with cold-blooded animals, but it can infect humans. To define the phylogeny of this species, and compare it to S. enterica, we have sequenced 28 isolates representing most of the known diversity of S. bongori. This cross-species analysis allowed us to confidently differentiate ancestral functions from those acquired following speciation, which include both metabolic and virulence-associated capacities. We show that, although S. bongori…
A single method for recovery and concentration of enteric viruses and bacteria from fresh-cut vegetables
2011
Fresh-cut vegetables are prone to be contaminated with foodborne pathogens during growth, harvest, transport and further processing and handling. As most of these products are generally eaten raw or mildly treated, there is an increase in the number of outbreaks caused by viruses and bacteria associated with fresh vegetables. Foodborne pathogens are usually present at very low levels and have to be concentrated (i.e. viruses) or enriched (i.e. bacteria) to enhance their detection. With this aim, a rapid concentration method has been developed for the simultaneous recovery of hepatitis A virus (HAV), norovirus (NV), murine norovirus (MNV) as a surrogate for NV, Escherichia coli O157:H7, List…
Antibacterial and antitumoral activities of new organotin(IV)-Schiff bases derivatives
2018
This preliminary report shows eight complexes of triorganotin(IV): Ph3SnOH and (CH3)3SnOH with four chelating imines on new synthesis. Of these ligands, two are salen-like (four coordination sites, two imidic, two phenoxidic) [1], one is a tetradentate pyrrole derivative [2] while the fourth, a vita- min B6 derivative, is pentadentate [3]. Ligands have been characterized by means of FT-IR, UV-Vis, Fluorescence, 1H- and 13C-NMR, LC-MS ESI triple quadrupole; complexes by means FT-IR, 1H- and 119Sn-NMR, LC-MS ESI, using the isotopic distribution pattern as a discriminant [4]. Geometry and nature of coordination complexes have been also evaluated using the 119Sn chemical shifts. Solid-state syn…