RESUMO
This paper evaluated magnetic nanoparticle-enhanced PCR for the detection and identification of Staphylococcus aureus and Salmonella enteritidis. Two different types of magnetic nanoparticles designated MPIO (iron concentration 2.5 mg/ml, size 1 µm) and NP (iron concentration 8.7 mg/ml, size 60 nm), both conjugated with S. aureus or S. enteritidis antibodies were evaluated as an enrichment procedure for PCR-detection of the pathogens in Trypticase Soy Broth, milk, blood and meat broth. Bacterial suspensions (1.5x108 cfu/ml) were prepared and serial diluted 10-1. The MPIO and NP nanoparticles were added, followed by incubation for 1 hour at room temperature, magnetic separation of the pellet, DNA extraction and PCR, targeting the femA and invA sequences. The nanoparticle-free and the NP-supplemented dilutions were positive down to the 1.5x102 cfu/ml concentration for both bacteria. The MPIO-supplemented dilutions were positive down to approx. 2x100 cfu/ml concentration, respectively. Bacteria-free TSB was negative by PCR. MPIO nanoparticles (size 1 µm) enhanced the detection of S. aureus and S. enteritidis by PCR, whilst NP nanoparticles (size 60 nm) did not, thus indicating that the size of the magnetic nanoparticles play a significant role in the enrichment procedure.
Assuntos
Nanopartículas de Magnetita , Reação em Cadeia da Polimerase/métodos , Salmonella enteritidis/isolamento & purificação , Staphylococcus aureus/isolamento & purificação , Animais , Sangue/microbiologia , Microbiologia de Alimentos , Ferro/química , Carne/microbiologia , Leite/microbiologia , Salmonella enteritidis/classificação , Staphylococcus aureus/classificaçãoRESUMO
Uric acid is a promising hydrophobic nitrogen source for biostimulation of microbial activities in oil-impacted marine environments. This study investigated metabolic processes and microbial community changes in a series of microcosms using sediment from the Mediterranean and the Red Sea amended with ammonium and uric acid. Respiration, emulsification, ammonium and protein concentration measurements suggested a rapid production of ammonium from uric acid accompanied by the development of microbial communities containing hydrocarbonoclastic bacteria after 3 weeks of incubation. About 80 % of uric acid was converted to ammonium within the first few days of the experiment. Microbial population dynamics were investigated by Ribosomal Intergenic Spacer Analysis and Illumina sequencing as well as by culture-based techniques. Resulting data indicated that strains related to Halomonas spp. converted uric acid into ammonium, which stimulated growth of microbial consortia dominated by Alcanivorax spp. and Pseudomonas spp. Several strains of Halomonas spp. were isolated on uric acid as the sole carbon source showed location specificity. These results point towards a possible role of halomonads in the conversion of uric acid to ammonium utilized by hydrocarbonoclastic bacteria.
Assuntos
Compostos de Amônio/metabolismo , Bactérias/genética , Consórcios Microbianos/genética , Ácido Úrico/metabolismo , Bactérias/metabolismo , Biodegradação Ambiental , DNA Bacteriano/genética , DNA Bacteriano/metabolismo , Jordânia , Mar Mediterrâneo , Petróleo/metabolismo , Reação em Cadeia da Polimerase , RNA Ribossômico 16S/genética , RNA Ribossômico 16S/metabolismo , Análise de Sequência de DNARESUMO
PURPOSE: The purpose of this study was to investigate the effect of different commercially used dental materials (RelyX Luting Plus and Dyract Extra) mixed with either a metallic ionic solution or a colloidal suspension of metallic nanoparticles. Both the solution and the suspension contained a mixture of silver, copper, and lithium ions. METHODS: The metal/ion-incorporated dental materials were prepared into disk-shaped samples and tested against the growth of Staphylococcus aureus. The susceptibility of bacteria against the antibacterial dental disks was tested using two methods: counting the colony-forming units per milliliter and disk diffusion (Kirby-Bauer). The incorporated materials (Dyract and Rely cement) were tested for ion release using flame atomic absorption spectroscopy. RESULTS: Assessment showed efficient antibacterial activity of metal ion-incorporated Rely luting cement, exhibited by the formation of inhibition zones larger than those formed by the standard antibiotic, as well as a reduction in bacterial number of sevenfold after incubation for 24 hours. Dyract material incorporated with nanoparticles showed no significant clear zones and had no inhibiting effect on bacterial colony numbers after incubation for 24 hours. The release of silver, copper, and lithium metal ions depended on the type of both dental material and the incorporated nanoagents. The metal ion-incorporated Rely Plus cement released the highest levels of metal ions, which was attributed to its antibacterial efficiency. CONCLUSION: Rely Plus cement incorporated with the nanoparticle suspension demonstrated high antibacterial potency, due to the release of the highest concentrations of silver, copper, and lithium metal ions. This work is the first direct comparative study of dental materials with different forms of nanomixtures (metallic nanoparticles and soluble metallic ions) and their antibacterial effects after incubation with bacterial culture for 24 hours.
Assuntos
Materiais Dentários/farmacologia , Nanopartículas/química , Staphylococcus aureus/crescimento & desenvolvimento , Antibacterianos/farmacologia , Contagem de Colônia Microbiana , Humanos , Testes de Sensibilidade Microbiana , Staphylococcus aureus/efeitos dos fármacosRESUMO
Two of the largest crude oil-polluted areas in the world are the semi-enclosed Mediterranean and Red Seas, but the effect of chronic pollution remains incompletely understood on a large scale. We compared the influence of environmental and geographical constraints and anthropogenic forces (hydrocarbon input) on bacterial communities in eight geographically separated oil-polluted sites along the coastlines of the Mediterranean and Red Seas. The differences in community compositions and their biodegradation potential were primarily associated (P < 0.05) with both temperature and chemical diversity. Furthermore, we observed a link between temperature and chemical and biological diversity that was stronger in chronically polluted sites than in pristine ones where accidental oil spills occurred. We propose that low temperature increases bacterial richness while decreasing catabolic diversity and that chronic pollution promotes catabolic diversification. Our results further suggest that the bacterial populations in chronically polluted sites may respond more promptly in degrading petroleum after accidental oil spills.
Assuntos
Bactérias/crescimento & desenvolvimento , Sedimentos Geológicos/microbiologia , Poluição por Petróleo , Petróleo/microbiologia , Temperatura , Aerobiose , Anaerobiose , Bactérias/genética , Biodegradação Ambiental , Simulação por Computador , Genes Bacterianos , Região do Mediterrâneo , Metaboloma , Metabolômica , Análise de Componente Principal , RNA Ribossômico 16S/genética , Reprodutibilidade dos TestesRESUMO
Mediterranean Sea is facing a very high risk of oil pollution due to the high number of oil extractive and refining sites along the basin coasts, and the intense maritime traffic of oil tankers. All the Mediterranean countries have adopted severe regulations for minimizing pollution events and bioremediation feasibility studies for the most urgent polluted sites are undergoing. However, the analysis of the scientific studies applying modern 'meta-omics' technologies that have been performed on marine oil pollution worldwide showed that the Southern Mediterranean side has been neglected by the international research. Most of the studies in the Mediterranean Sea have been done in polluted sites of the Northern side of the basin. Those of the Southern side are poorly studied, despite many of the Southern countries being major oil producers and exporters. The recently EU-funded research project ULIXES has as a major objective to increase the knowledge of the bioremediation potential of sites from the Southern Mediterranean countries. ULIXES is targeting four major polluted sites on the coastlines of Egypt, Jordan, Morocco and Tunisia, including seashore sands, lagoons, and oil refinery polluted sediments. The research is designed to unravel, categorize, catalogue, exploit and manage the diversity and ecology of microorganisms thriving in these polluted sites. Isolation of novel hydrocarbon degrading microbes and a series of state of the art 'meta-omics' technologies are the baseline tools for improving our knowledge on biodegradation capacities mediated by microbes under different environmental settings and for designing novel site-tailored bioremediation approaches. A network of twelve European and Southern Mediterranean partners is cooperating for plugging the existing gap of knowledge for the development of novel bioremediation processes targeting such poorly investigated polluted sites.
Assuntos
Oceanos e Mares , Petróleo/microbiologia , Microbiologia da Água , Poluentes Químicos da Água , Biodegradação Ambiental , Região do MediterrâneoRESUMO
The leaves of Tamarix, a salt-secreting desert tree, form an extreme niche that harbors a unique microbial community. In view of the global distribution of this tree, its island-like phyllosphere is highly suitable for studying microbial diversity along geographical gradients. Here we present an analysis of microbial community diversity using leaf surface samples collected at six different sites, on both sides of the Dead Sea, over a period of one year. Biodiversity analysis of denaturing gradient gel electrophoresis (DGGE) patterns of the bacterial 16S rRNA gene revealed a significant degree of bacterial community similarity within trees sampled at the same site, much higher than the similarity between trees from different geographical locations. Statistical analysis indicated that the degree of similarity was negatively correlated with the distance between sampling sites, and that a weak correlation existed between diversity and leaf pH.
Assuntos
Consórcios Microbianos/genética , Folhas de Planta/microbiologia , Tamaricaceae/microbiologia , Alphaproteobacteria/isolamento & purificação , Bacillaceae/isolamento & purificação , Bacteroidetes/isolamento & purificação , Betaproteobacteria/isolamento & purificação , Biodiversidade , DNA Bacteriano/análise , DNA Bacteriano/genética , Eletroforese em Gel de Gradiente Desnaturante/métodos , Gammaproteobacteria/isolamento & purificação , Consórcios Microbianos/fisiologia , Filogenia , Folhas de Planta/química , RNA Ribossômico 16S/genética , Tolerância ao Sal , Cloreto de SódioRESUMO
The thermal springs of Zerka Ma'in, with waters emerging at temperatures up to 63 degrees C, have been of interest to biologists already from the beginning of the 19th century. These waters, springing out from below ground and flowing into the hypersaline Dead Sea, form an isolated environment from a biogeographic point of view. We have investigated the molecular diversity of the cyanobacteria in the springs. The diversity discovered was large, defining operational taxonomic units (OTUs) by a cutoff of 97% similarity; 10 major OTUs were found, including an as yet unidentified cluster of cyanobacteria. The various patterns of similarities of our sequences to others obtained from different thermal environments worldwide led us to rethink the common theories in biogeography. Based on the data obtained, we suggest that there is no constant geographical separation of microorganisms; however, local speciation does occur at a rate dictated mainly by local community dynamics and the rate of entrance of new organisms into the ecosystem.
Assuntos
Cianobactérias/classificação , Cianobactérias/isolamento & purificação , Ecossistema , Fontes Termais/microbiologia , Sequência de Bases , Biodiversidade , Cianobactérias/genética , DNA Bacteriano/genética , Geografia , Jordânia , Filogenia , Reação em Cadeia da Polimerase , Temperatura , Microbiologia da ÁguaRESUMO
Three sets of known Salmonella enterica-specific primers were used collectively, for the first time, to evaluate the use of multiplex polymerase chain reaction (m-PCR) as a diagnostic tool to detect Salmonella enterica in naturally contaminated meat and poultry products. For this purpose a total of 300 samples representing the most frequently used fresh and frozen meat (beef and lamb) and poultry (chicken) products (whole, cut, ground, and processed) were collected from eight locations within Irbid city (Jordan). After an enrichment step, DNA was extracted directly from each food sample and amplified using six Salmonella enterica specific primers. Samples were also analyzed using conventional microbiological methods for the confirmation of Salmonella enterica presence. Out of 300 samples, 93 samples were positive by m-PCR. On the other hand, 67 samples were positive by conventional microbiological methods and only 26 samples were positive by m-PCR alone. The primer pairs, used here, proved to be highly specific for Salmonella enterica. Using m-PCR, Salmonella enterica detection could be achieved easily and the results had been confirmed effortlessly within a short period of time (24-36 hours) compared to 3-8 days for the conventional microbiological methods. Our findings emphasize the value of using a combination of specific primer pairs instead of a single primer pair in the detection process to minimize any chance for any inherent experimental or natural error.
Assuntos
Galinhas/microbiologia , Microbiologia de Alimentos , Reação em Cadeia da Polimerase/métodos , Salmonella enterica/isolamento & purificação , Ovinos/microbiologia , Animais , Sensibilidade e EspecificidadeRESUMO
Secondary-treated wastewater was used to irrigate forage crops during two years (1994 and 1995). The bacteriological quality of the soil irrigated with both secondary treated wastewater (without chlorination) and with potable water was evaluated. The following three treatments were investigated in this study: i) irrigation with potable water in amount equivalent to 100% of the class A Pan evaporation reading (as taken from the nearest Meteorological Weather Station); ii) irrigation with treated wastewater in amount equivalent to 100% of the A Pan reading and iii) irrigation with treated wastewater in amount equivalent to 125% of the A Pan reading. At the end of the last growing season, soil samples were collected at two soil depths and subjected to microbiological analysis. The bacteriological analysis showed that the total aerobic bacterial counts of surface soil were similar in all irrigated plots, suggesting that the use of this wastewater did not stimulate or inhibit these microflora. Surface soil was found to have higher bacterial counts than deeper soil suggesting bacterial removal from irrigation water by the first few centimeters of soil due to natural infiltration of soil. The total coliforms ranged from 2.1 x 10(3) CFU/g to 4.2 x 10(3) CFU/g while fecal coliforms were less, ranging from 1.2 x 10(2) CFU/g to 4.2 x 10(2) CFU/g. No detectable helminth eggs were recorded in the treated wastewater used for irrigation. The results strongly suggest the necessity to treat wastewater effluents to an extent to which no or very few residual bacterial contaminants will be detected.