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At least 829 records · Page 46Linked to original sources
PubMed1991

Cockroaches (Blattella germanica) as carriers of microorganisms of medical importance in hospitals.

A study was conducted to isolate and identify microorganisms of medical importance from cockroaches (Blattella germanica) and to ascertain their vector potential in the epidemiology of nosocomial infections. Bacteria, fungi and parasites of medical importance were isolated and identified. Important bacterial pathogens responsible for wound infections, were further studies by antibiograms. One hundred and fifty-eight out of 159 (99.4%) cockroaches collected from hospital (test) and 113 out of 120 (94.2%) cockroaches collected from residential areas (control) were carrying medically important microorganisms (P less than 0.05). significantly higher (P less than 0.001) number of test cockroaches were carrying a higher bacterial load (1 x 10(4) and 1 x 10(5] as compared to control cockroaches. Multiple drug-resistant bacterial were isolated from test cockroaches. The diversity of drug-resistant bacterial species isolated from test cockroaches suggests their involvement in the transmission of drug-resistant bacteria. Various fungi and parasitic cysts of medical importance were also isolated from the test and control cockroaches, but the carriage rates were low. The findings suggest that cockroaches, in hospitals, can act as potential vectors of medically important bacteria/parasites/fungi.

Animals↗
PubMed2003

Efficacy of microorganisms antagonistic to Rhizoctonia cerealis and their cell wall degrading enzymatic activities.

The effect of Trichoderma atroviride, T. harzianum, T. longibrachiatum, Clonostachys rosea and Bacillus subtilis isolates applied to wheat seeds against Rhizoctonia cerealis disease of seedlings was investigated under controlled greenhouse conditions. Most Trichoderma isolates significantly reduced the incidence of disease compared with the infected control. Bacillus subtilis was also effective against sharp eyespot, although less active than Trichoderma spp. Interactions between the antagonistic microorganisms and the cereal pathogenic fungus in dual culture experiments on agar growth medium were also studied. Almost all tested antagonists showed competitive activity against R. cerealis: inhibition of its mycelial growth and hyphal interaction. The production of extracellular beta-N-acetylhexosaminidase, chitin 1,4-beta-chitobiosidase, glucan 1,3-beta-glucosidase and protease activity by the tested microorganisms in the presence of cell walls of R. cerealis was then determined. All isolates showed glucosaminidase and chitobiosidase activity. They also produced glucosidase activity, except B. subtilis, whereas only C. rosea, B. subtilis and one isolate of T. harzianum showed detectable levels of protease activity.

Antibiosis↗
PubMed2001

Lectin and carbohydrate affinity capture surfaces for mass spectrometric analysis of microorganisms.

In a preliminary report (Bundy, J. L.; Fenselau, C. Anal. Chem 1999, 71, 1460-1463), we demonstrated the use of lectin-derivatized surfaces to capture and concentrate complex carbohydrates as well as microorganisms from sample matrixes unamenable to direct MALDI mass spectrometry. Here, we extend the work to include samples representative of a wider variety of microorganisms of importance to human health and of enveloped viruses. In this study, lectins were immobilized directly to a membrane surface via primary amines. A complementary approach was also explored, using immobilized carbohydrates to capture bacteria via microbial lectins expressed on their surfaces. The carbohydrate-based surfaces were constructed by first immobilizing streptavidin to the membrane, followed by attachment of a commercially produced biotin/carbohydrate polymer. Acid treatment of the sample prior to mass spectrometric analysis permits the observation of protein biomarkers from the captured microbial samples in the 5-20 kDa mass range. Bacteria samples were detected from physiological buffers, urine, milk, and processed chicken samples using the biocapture probes. Viral samples were detected from culture based on glycoprotein moieties desorbed directly from the surface. The carbohydrate-based system provided greater sensitivity than the lectin system, possibly due to the larger number of accessible saccharide ligands on the polymer.

Carbohydrates↗
PubMed2001

Bioinformatics and mass spectrometry for microorganism identification: proteome-wide post-translational modifications and database search algorithms for characterization of intact H. pylori.

MALDI-TOF mass spectrometry has been coupled with Internet-based proteome database search algorithms in an approach for direct microorganism identification. This approach is applied here to characterize intact H. pylori (strain 26695) Gram-negative bacteria, the most ubiquitous human pathogen. A procedure for including a specific and common posttranslational modification, N-terminal Met cleavage, in the search algorithm is described. Accounting for posttranslational modifications in putative protein biomarkers improves the identification reliability by at least an order of magnitude. The influence of other factors, such as number of detected biomarker peaks, proteome size, spectral calibration, and mass accuracy, on the microorganism identification success rate is illustrated as well.

Algorithms↗
PubMed2005

Chemometric studies for the characterization and differentiation of microorganisms using in situ derivatization and thermal desorption ion mobility spectrometry.

Whole-cell bacteria were characterized and differentiated by thermal desorption ion mobility spectrometry and chemometric modeling. Principal component analysis was used to evaluate the differences in the ion mobility spectra of whole-cell bacteria and the fatty acid methyl esters (FAMEs) generated in situ after derivatization of the bacterial lipids. Alternating least squares served to extract bacterial peaks from the complex ion mobility spectra of intact microorganisms and, therefore, facilitated the characterization of bacterial strains, species, and Gram type. In situ thermal hydrolysis/methylation with tetramethylammonium hydroxide was necessary for the differentiation of Escherichia coli strains, which otherwise could not be distinguished by spectra acquired with the ITEMISER ion mobility spectrometer. The addition of the methylating agent had no effect on Gram-positive bacteria, and therefore, they could not be differentiated by genera. The classification of E. coli strains was possible by analysis of the IMS spectra from the FAMEs generated in situ. By using the fuzzy multivariate rule-building expert system and cross-validation, a correct classification rate of 96% (22 out of 23 spectra) was obtained. Chemometric modeling on bacterial ion mobility spectra coupled to thermal hydrolysis/methylation proved a simple, rapid (2 min/sample), inexpensive, and sensitive technique to characterize and differentiate intact microorganisms. The ITEMISER ion mobility spectrometer could detect as few as 4 x 10(6) cells/sample.

Escherichia coli↗
PubMed2006

Capillary isoelectric focusing and fluorometric detection of proteins and microorganisms dynamically modified by poly(ethylene glycol) pyrenebutanoate.

The nonionogenic pyrene-based tenside, poly(ethylene glycol) pyrenebutanoate, was prepared and applied in capillary isoelectric focusing with fluorometric detection. This dye was used here as a buffer additive in capillary isoelectric focusing for a dynamic modification of the sample of proteins and microorganisms. The values of the isoelectric points of the labeled bioanalytes were calculated with use of the fluorescent pI markers and were found comparable with pI of the native compounds. The mixed cultures of proteins and microorganisms, Escherichia coli CCM 3954, Staphylococcus epidermidis CCM 4418, Proteus vulgaris, Enterococcus faecalis CCM 4224, and Stenotrophomonas maltophilia, the strains of the yeast cells, Candida albicans CCM 8180, Candida krusei, Candida parapsilosis, Candida glabrata, Candida tropicalis, and Saccharomyces cerevisiae were reproducibly focused and separated by the suggested technique. Using UV excitation for the on-column fluorometric detection, the minimum detectable amount was down to 10 cells injected on the separation capillary.

Bacteria↗
PubMed2000

Raman spectroscopic method for identification of clinically relevant microorganisms growing on solid culture medium.

Routine clinical microbiological identification of pathogenic microorganisms is largely based on nutritional and biochemical tests. In the case of severely ill patients, the unavoidable time delay associated with such identification procedures can be fatal. We present a novel identification method based on confocal Raman microspectroscopy. With this approach it is possible to obtain Raman spectra directly from microbial microcolonies on the solid culture medium, which have developed after only 6 h of culturing for the most commonly encountered organisms. Due to the limited thickness of microcolonies, some of the underlying culture medium is sampled together with the bacteria. Spectra measured at different depths in a microcolony contain different amounts of the medium signal. A mathematical routine, involving vector algebra, is described for the nonsubjective correction of spectra for variable signal contributions of the medium. To illustrate the possibilities of our approach for the identification of microorganisms, Raman spectra were collected from 6-h microcolonies of five bacterial strains on solid culture medium. The classification results show that confocal Raman microspectroscopy has great potential as a powerful new tool in clinical diagnostic microbiology.

Bacteriological Techniques↗
PubMed2001

Methyl tert-butyl ether biodegradation by indigenous aquifer microorganisms under natural and artificial oxic conditions.

Microbial communities indigenous to a shallow groundwater system near Beaufort, SC, degraded milligram per liter concentrations of methyl tert-butyl ether (MTBE) under natural and artificial oxic conditions. Significant MTBE biodegradation was observed where anoxic, MTBE-contaminated groundwater discharged to a concrete-lined ditch. In the anoxic groundwater adjacent to the ditch, concentrations of MTBE were > 1 mg/L. Where groundwater discharge occurs, dissolved oxygen (DO) concentrations beneath the ditch exceeded 1.0 mg/Lto a depth of 1.5 m, and MTBE concentrations decreased to <1 microg/L prior to discharge. MTBE mass flux calculations indicate that 96% of MTBE mass loss occurs in the relatively small oxic zone prior to discharge. Samples of a natural microbial biofilm present in the oxic zone beneath the ditch completely degraded [U-14C]MTBE to [14C]CO2 in laboratory liquid culture studies, with no accumulation of intermediate compounds. Upgradient of the ditch in the anoxic, MTBE- and BTEX-contaminated aquifer, addition of a soluble oxygen release compound resulted in oxic conditions and rapid MTBE biodegradation by indigenous microorganisms. In an observation well located closest to the oxygen addition area, DO concentrations increased from 0.4 to 12 mg/L in <60 days and MTBE concentrations decreased from 20 to 3 mg/L. In the same time period at a downgradient observation well, DO increased from <0.2 to 2 mg/L and MTBE concentrations decreased from 30 to <5 mg/L. These results indicate that microorganisms indigenous to the groundwater system at this site can degrade milligram per liter concentrations of MTBE under natural and artificial oxic conditions.

Bacteria, Anaerobic↗
PubMed2004

Development and evaluation of microarray-based whole-genome hybridization for detection of microorganisms within the context of environmental applications.

The detection and identification of microorganisms in natural communities is a great challenge to biologists. Microarray-based genomic technology provides a promising high-throughput alternative to traditional microbial characterization. A novel prototype microarray containing whole genomic DNA, termed community genome array (CGA), was constructed and evaluated. Microarray hybridizations at 55 degrees C using 50% formamide permitted the examined bacteria to be distinguished at the species level, while strain-level differentiation was obtained at hybridization temperatures of 65 or 75 degrees C. The detection limit was estimated to be approximately 0.2 ng with genomic DNA from a single pure culture using a reduced hybridization volume (3 microL). Using mixtures of known amounts of DNA or a known number of cells from 14 or 16 different species, respectively, about 5 ng of genomic DNA or 2.5 x 10(5) cells were detected under the hybridization conditions used. In addition, strong linear relationships were observed between hybridization signal intensity and target DNA concentrations for pure cultures, a mixture of DNA templates, and a population of mixed cells (r2 = 0.95-0.98, P < 0.01). Finally, the prototype CGA revealed differences in microbial community composition in soil, river, and marine sediments. The results suggest that CGA hybridization has potential as a specific, sensitive, and quantitative tool for detection and identification of microorganisms in environmental samples.

Bacteria↗
PubMed2002

In vitro efficacy of plant volatiles for inhibiting the growth of fruit and vegetable decay microorganisms.

The effects of acetaldehyde, benzaldehyde, cinnamaldehyde, ethanol, benzyl alcohol, nerolidol, 2-nonanone, beta-ionone, and ethyl formate vapors on the growth of Rhizopus stolonifer, Penicillium digitatum, Colletotrichum musae, Erwinia carotovora, and Pseudomonas aeruginosa on agar medium were evaluated. The aldehydes were found to be the strongest growth inhibitors and the most lethal to the fungal spores and mycelia and bacterial cells. The average minimum inhibitory concentrations (MICs) of aldehydes that were germicidal to decay microorganisms were 0.28, 0.49, and 0.88 mmol per Petri dish, for cinnamaldehyde, benzaldehyde, and acetaldehyde, respectively. Ethanol also inhibited growth completely, but the MIC, which was 14.6 mmol per Petri dish, was significantly higher than those of the aldehydes. Ethanol can be considered germistatic because the alcohol does not inhibit germination of spores completely; it completely controlled only mycelial growth. The ketones tended to be effective only on P. digitatum and C. musae, whereas ethyl formate was not effective except on P. digitatum. The concentration of a volatile compound in the headspace of the Petri dish and its diffusion into the medium largely determined its efficacy against decay microorganisms.

Agar↗
PubMed2006

Natural products from plant-associated microorganisms: distribution, structural diversity, bioactivity, and implications of their occurrence.

A growing body of evidence suggests that plant-associated microorganisms, especially endophytic and rhizosphere bacteria and fungi, represent a huge and largely untapped resource of natural products with chemical structures that have been optimized by evolution for biological and ecological relevance. A diverse array of bioactive small molecule natural products has been encountered in these microorganisms. The structures of over 230 metabolites isolated and characterized from over 70 plant-associated microbial strains during the past four years are presented with information on their hosts, culture conditions, and biological activities. Some significant biological and ecological implications of their occurrence are also reviewed.

Bacteria↗
PubMed1998

Biodegradation of crude oil by soil microorganisms in the tropic.

Five microorganisms, three bacteria and two yeasts, capable of degrading Tapis light crude oil were isolated from oil-contaminated soil in Bangkok, Thailand. Soil enrichment culture was done by inoculating the soil in mineral salt medium with 0.5% v/v Tapis crude oil as the sole carbon source. Crude oil biodegradation was measured by gas chromatography method. Five strains of pure microorganisms with petroleum degrading ability were isolated: three were bacteria and the other two were yeasts. Candida tropicalis strains 7Y and 15Y were identified as efficient oil degraders. Strain 15Y was more efficient, it was able to reduce 87.3% of the total petroleum or 99.6% of n-alkanes within the 7-day incubation period at room temperature of 25 +/- 2 degrees C.

Biodegradation, Environmental↗
PubMed1998

Detection and quantification of microorganisms in anaerobic bioreactors.

The presence of sulfate in anaerobic reactors can trigger competitive and syntrophic interactions between various groups of microorganisms, such as sulfate reducers, methanogens and acetogens. In order to steer the reactor process in the direction of sulfidogenesis or methanogenesis, it is essential to get insight into the population dynamics of these groups of microorganisms upon changes in the reactor operating conditions. Several methods exist to characterize and quantify the microbial sludge composition. Combining classical microbiological and modern molecular-based sludge characterization methods has proven to be a powerful approach to study the microbial composition of the anaerobic sludge.

Journal Article↗
PubMed1998

Recovery of gold from thiourea solutions using microorganisms.

The recovery of gold from gold-thiourea solutions using various types of waste biomass was investigated. All organisms tested, namely, Saccharomyces cerevisiae, Spirulina platensis and Streptomyces erythraeus removed gold rapidly from gold-thiourea solutions. The process of gold accumulation was pH-dependent for Saccharomyces ceresvisiae and Streptomyces erythraeus and independent of pH in the case of Spirulina platensis. Of all strains of microorganisms examined, Spirulina platensis had the highest affinity and capacity for gold even at low pH values. Thus, all three microorganisms tested for their ability to recover gold from gold-thiourea solutions can therefore be used in biotechnological applications, especially Spirulina platensis which has the highest binding capacity for gold at low pH values.

Bacterial Proteins↗
PubMed1997

Metabolism of azetirelin, a new thyrotropin-releasing hormone (TRH) analogue, by intestinal microorganisms.

PURPOSE: We evaluated the effect of luminal bacterial metabolism on intestinal absorption of azetirelin in rats. In vitro characteristics of bacterial metabolism of azetirelin were also investigated with the goal of overcoming the low stability of the peptidic drug against luminal microorganisms. METHODS: Plasma azetirelin levels after oral administration to antibiotic-pretreated rats was examined. In vitro incubation experiments with bacterial suspensions were also performed to clarify the location of azetirelin breakdown activity as well as the effects of oxygen, pH, and various protease inhibitors on drug metabolism. RESULTS: Plasma azetirelin levels were sustained after oral administration to antibiotic-treated rats. Incubation with rat luminal contents demonstrated that azetirelin was metabolized by anacrobic bacteria, which are predominant in the distal intestine. Fecal suspensions from rats, dogs, and humans showed comparable metabolic activity. Azetirelin breakdown in the bacterial suspension was pH-dependent and was inhibited in the presence of bacitracin or puromycin. CONCLUSIONS: Bacterial metabolism influences the degree of absorption of azetirelin in the distal intestine. Control of the luminal pH environment may be a practical method for improving the stability of azetirelin against intestinal microorganisms.

Animals↗
PubMed2002

Effects of asparaginase and polyphenol oxidase on adhesive characteristics of microorganisms.

We studied the effects of polyphenol oxidase and asparaginase on microorganism adhesion to buccal epithelial cells. These enzymes reduced adhesion of pathogenic microorganisms (uropathogenic and Escherichia coli, Salmonella enteritidis, Entamoeba spp., Influenza virus, Candida albicans, Streptococcus spp.) and had virtually no effect on adhesive characteristics of probiotic variants of Escherichia coli and Lactobacillus fermentum.

Asparaginase↗
PubMed2001

Microorganisms isolated from root canals presenting necrotic pulp and their drug susceptibility in vitro.

The knowledge about causative agents involved in endodontic infections is increasing, especially due to the improvement of culture techniques for anaerobic bacteria, showing that these microorganisms are predominant in this pathology. In this study, 31 canals with pulp necrosis were microbiologically analyzed before and after manipulation. Obligate and facultative anaerobes, microaerophilic bacteria and yeasts were recovered from 24, 14, 5 and 2 clinical specimens, respectively. The most frequent genera were Prevotella, Fusobacterium, Lactobacillus, Streptococcus, Clostridium and Peptostreptococcus for bacteria and Candida and Saccharomyces for yeasts. Strong positive associations, using an odds ratio system, were found between Clostridium and Prevotella and between Peptostreptococcus and Fusobacterium. Even after the instrumentation and the use of Ca(OH)2, facultative anaerobes were detected in two root canals and yeasts in three. Microorganisms were isolated from seven canals at the end of the endodontic treatment: facultative anaerobes from five and yeasts from one. The microbiological evaluation of root canals with pulp necrosis suggests the presence of polymicrobial infections, mainly involving obligate anaerobes, and shows that the infection may persist after treatment.

Bacteria, Anaerobic↗