Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “MICROORGANISMS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,531 records · Page 85Linked to original sources
PubMed2002

The antioxidant cocktail effective microorganism X (EM-X) inhibits oxidant-induced interleukin-8 release and the peroxidation of phospholipids in vitro.

The antioxidant beverage EM-X is derived from the ferment of unpolished rice, papaya, and sea-weeds with effective microorganisms. Oxidative stress enhances the expression of proinflammatory genes, causing the release of the chemokine interleukin-8 (IL-8), which mediates a multitude of inflammatory events. Human alveolar epithelial cells (A549) were treated with H(2)O(2) (100 microM) or TNF-alpha (10ng/ml) alone or with the addition of EM-X (100 microl/ml), incubated for 20h, and the release of IL-8, measured using ELISA. EM-X inhibited the release of IL-8 at the transcriptional level in A549 cells. EM-X also decreased the iron/ascorbate dependent peroxidation of ox-brain phospholipids in a concentration dependent manner. A TEAC value of 0.10+/-0.05mM was obtained for EM-X, indicating antioxidant potential. We suggest that the anti-inflammatory and antioxidant properties of EM-X are dependent on the flavonoid contents of the beverage.

Antioxidants↗
PubMed1976

Swimming of flagellated microorganisms.

The swimming motion of a microorganism with a single flagellum is investigated for both helical and planar flagellar motion. First the force and torque exerted on the organism by the surrounding fluid are calculated in terms of the specified flagellar motion and the unknown linear and angular velocity of the whole organism. Then these unknown velocities are determined by the condition that the net force and torque on the organism are zero. Using these velocities, the trajectory of the organism is found. In the case of helical flagellar motion, the path of the entire organism is found to be a helix of small radius. The axis of the flagellum is not parallel to the axis of the helical path, but makes a small angle with it and precesses around it. If the flagellar motion is planar and sinusoidal, then the trajectory of the organism is found to be a straight line with small oscillations about it. Each point of the flagellum also oscillates longitudinally with double the frequency of the transverse oscillation, producing a figure eight motion. However if the flagellar motion is planar and asymmetric, then the trajectory is found to be a circle with small superposed oscillations. These conclusions account for the observed helical and circular trajectories of sperm, and for the figure eight motion of the tip of the flagellum in the planar case.

Animals↗
PubMed1977

Hydrodynamic theory of swimming of flagellated microorganisms.

A theory of the type commonly used in polymer hydrodynamics is developed to calculate swimming properties of flagellated microorganisms. The overall shape of the particle is modeled as an array of spherical beads which act, at the same time, as frictional elements. The fluid velocity field is obtained as a function of the forces acting at each bead through Oseen-type, hydrodynamic interaction tensors. From the force and torque equilibrium conditions, such quantities as swimming velocity, angular velocity, and efficiency can be calculated. Application is made to a spherical body propelled by a helical flagellum. A recent theory by Lighthill, and earlier formulations based on tangential and normal frictional coefficients of a curved cylinder, CT and CN, are analyzed along with our theory. Although all the theories predict similar qualitative characteristics, such as optimal efficiency and the effect of fluid viscosity, they lead to rather different numerical values. In agreement with Lighthill, we found the formalisms based on CN and CT coefficients to be somewhat inaccurate, and head-flagellum interactions are shown to play an important role.

Flagella↗
PubMed1989

Kinematics of helical motion of microorganisms capable of motion with four degrees of freedom.

The kinematics of helical motion are described for an organism with four degrees of freedom, relative to the organism's frame of reference. It can rotate about any of three orthogonal axes, but can translate only in the direction of one axis. In particular, equations are developed for calculating the pitch, radius, and angular frequency of the helical path from the translational and rotational velocities of the microorganism, correcting, and expanding the analysis of Gray J. (1955. J. Exp. Biol. 32:775-801).

Cell Movement↗
PubMed1993

The role of hydrodynamic interaction in the locomotion of microorganisms.

A general Boundary Element Method is presented and benchmarked with existing Slender Body Theory results and reflection solutions for the motion of spheres and slender bodies near plane boundaries. This method is used to model the swimming of a microorganism with a spherical cell body, propelled by a single rotating flagellum. The swimming of such an organism near a plane boundary, midway between two plane boundaries or in the vicinity of another similar organism, is investigated. It is found that only a small increase (less than 10%) results in the mean swimming speed of an organism swimming near and parallel to another identical organism. Similarly, only a minor propulsive advantage (again, less than 10% increase in mean swimming speed) is predicted when an organism swims very close and parallel to plane boundaries (such as a microscopic plate and (or) a coverslip, for example). This is explained in terms of the flagellar propulsive advantage derived from an increase in the ratio of the normal to tangential resistance coefficients of a slender body being offset by the apparently equally significant increase in the cell body drag. For an organism swimming normal to and toward a plane boundary, however, it is predicted that (assuming it is rotating its flagellum, relative to its cell body, with a constant angular frequency) the resulting swimming speed decreases asymptotically as the organism approaches the boundary.

Bacterial Physiological Phenomena↗
PubMed1997

Geochemical constraints on chemolithoautotrophic metabolism by microorganisms in seafloor hydrothermal systems.

Mixing of hydrothermal fluids and seawater at the ocean floor, combined with slow reaction kinetics for oxidation/reduction reactions, provides a source of metabolic energy for chemolithotrophic microorganisms which are the primary biomass producers for an extensive submarine ecosystem that is essentially independent of photosynthesis. Thermodynamic models are used to explore geochemical constraints on the amount of metabolic energy potentially available from chemosynthetic reactions involving S, C, Fe, and Mn compounds during mixing of hydrothermal fluids with seawater. For the vent fluid used in the calculations (EPR 21 degrees N OBS), the model indicates that mixing environments are favorable for oxidation of H2S, CH4, Fe2+ and Mn2+ only below approximately 38 degrees C, with methanogenesis and reduction of sulfate or S degrees favored at higher temperatures, suggesting that environments dominated by mixing provide habitats for mesophilic (but not thermophilic) aerobes and thermophilic (but not mesophilic) anaerobes. A maximum of approximately 760 cal per kilogram vent fluid is available from sulfide oxidation while between 8 and 35 cal/kg vent fluid is available from methanotrophy, methanogenesis, oxidation of Fe or Mn, or sulfate reduction. The total potential for chemosynthetic primary production at deep-sea hydrothermal vents globally is estimated to be about 10(13) g biomass per year, which represents approximately 0.02% of the global primary production by photosynthesis in the oceans. Thermophilic methanogens and sulfate- and S degree-reducers are likely to be the predominant organisms in the walls of vent chimneys and in the diffuse mixing zones beneath warm vents, where biological processes may contribute to the high methane concentrations of vent fluids and heavy 34S/32S ratios of vent sulfide minerals. The metabolic processes taking place in these systems may be analogs of the first living systems to evolve on the Earth.

Aerobiosis↗
PubMed2002

Investigating the effects of protein patterns on microorganism identification by high-performance liquid chromatography-mass spectrometry and protein database searches.

High-performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESI-MS) has been employed for separation and detection of protein biomarkers from E. coli samples. LC-MS is suitable for microbial identification because it can couple on-line with sample clean-up devices and is readily amenable to automation. In this work, we have investigated the effects of sample preparation methods on the detection of bacterial proteins by LC-MS. Many factors effect the degree of variations in the protein patterns (i.e. number and masses of proteins). For example, changing the polarity as well as pH of the extraction solvent may control the number of detected proteins. It is also noted that the protein patterns can vary even when the total ion chromatography plots seem to be the same under the same sample preparation conditions. Further, we have tested experimentally the influence of LC-MS-analyzed protein patterns (molecular masses between 2000 and 60,000) on microbial identification by protein database searches. This is in contrast to the current database search approach, where only the masses of smaller proteins (< or = 20,000) from direct matrix-assisted laser/desorption ionization MS are used. In spite of the variations in protein patterns, all the database search results show that the best matches come from the correct microorganism.

Automation↗
PubMed1988

Adherence of urease-induced crystals to rat bladder epithelium following acute infection with different uropathogenic microorganisms.

Apart from urine supersaturation with respect to struvite and calcium phosphate, crystal retention is considered to be necessary for the formation of infection stones. This study was performed to investigate the role of the mucous coat in rat bladders in the adhesion of sterile urease-induced crystals and to determine to what extent the adhesion was influenced by infection. Elimination of the mucous coat with 0.1 M HCl increased the adherence of crystals six times compared to that in bladders with an intact mucous coat. Infection with Proteus mirabilis, Escherichia coli, enterococci and Ureaplasma urealyticum increased the adherence six, five, four and two times, respectively. Injury to the mucous coat may thus be one mechanism by which microorganisms can contribute to the formation of infection stones in the urinary tract.

Animals↗
PubMed2003

A simple method to reduce discharge of sewage microorganisms from an Antarctic research station.

The majority of coastal Antarctic stations release untreated sewage into the near-shore marine environment. This study examined bacterial reproduction within the temporary sewage-holding tanks of Rothera Research Station (Adelaide Island, Antarctic Peninsula) and monitored sewage pollution in the local marine environment. By continuously flushing the sewage-holding tanks with cold seawater we inhibited microbial reproduction and decreased the numbers of bacteria subsequently released into the sea by >90%. The widespread use of this simple method could significantly reduce the numbers of faecal coliform and other non-native microorganisms introduced into the Antarctic marine environment.

Antarctic Regions↗
PubMed1980

Rapid identification of the invading microorganism.

There has been great progress in recent years in the development of sensitive techniques for the rapid identification of microorganisms in material obtained from patients with a wide variety of infections. While some of these methods employ chemical and microscopic analysis, most investigative interest has centered on the detection of specific antigens by exquisitely sensitive immunologic tests. Properly used, these techniques can yield specific diagnoses within a matter of a few hours, thus facilitating management of both patient and others who are at risk for contracting the infection. Because these techniques detect antigens rather than viable organisms, specific diagnosis is also possible when antibiotic therapy administered prior to testing has rendered cultures sterile. In some instances assay of the concentration of antigen present in biologic fluids can be used in prognosis.

Agglutination Tests↗
PubMed1995

Reducing the spread of antimicrobial-resistant microorganisms. Control of vancomycin-resistant enterococci.

Strategies to reduce the spread of hospital-acquired microorganisms resistant to multiple antimicrobial agents are discussed. Because hospitals have experienced a rapid increase in the incidence of infection and colonization with vancomycin-resistant enterococci (VRE) in the past 5 years, the Hospital Infection Control Practices Advisory Committee of the Centers for Disease Control and Prevention has issued recommendations for preventing the spread of vancomycin resistance. Controlling VRE dissemination in pediatric patients requires prompt detection of VRE by microbiology laboratories, education of staff and families about VRE, use of infection control measures to prevent person-to-person VRE transmission, and prudent vancomycin use.

Child↗
PubMed1997

Biochemical activities of berberine, palmatine and sanguinarine mediating chemical defence against microorganisms and herbivores.

The alkaloids berberine, palmatine and sanguinarine are toxic to insects and vertebrates and inhibit the multiplication of bacteria, fungi and viruses. Biochemical properties which may contribute to these allelochemical activities were analysed. Acetylcholine esterase, butyrylcholinesterase, choline acetyl transferase, alpha 1- and alpha 2-adrenergic, nicotinergic, muscarinergic and serotonin2 receptors were substantially affected. Sanguinarine appears to be the most effective inhibitor of choline acetyl-transferase (IC50 284 nM), while the protoberberines were inactive at this target. Berberine and palmatine were most active at the alpha 2-receptor (binding with IC50 476 and 956 nM, respectively). Furthermore, berberine and sanguinarine intercalate DNA, inhibit DNA synthesis and reverse transcriptase. In addition, sanguinarine (but not berberine) affects membrane permeability and berberine protein biosynthesis. In consequence, these biochemical activities may mediate chemical defence against microorganisms, viruses and herbivores in the plants producing these alkaloids.

Acetylcholinesterase↗
PubMed2001

The role of indigenous microorganisms in suppression of Salmonella regrowth in composted biosolids.

Composting is commonly used as an effective means of stabilizing wastewater biosolids and reducing pathogens to very low concentrations. However, it has been shown that under certain conditions Salmonella can regrow in previously composted biosolids. Growth of seeded Salmonella typhimurium in composted biosolids ranging from two weeks to two years maturity was monitored. Results from sterile and non-sterile composted biosolids were compared. Seeded S. typhimurium colonized rapidly in sterilized biosolids reaching a maximum population density of more than 10(8) g(-1). Growth of seeded S. typhimurium was suppressed in non-sterilized compost with a maximum population density of less than 10(3) g(-1). There was a significant decline in the growth rate of seeded Salmonella in sterilized compost when the compost was stored, suggesting that bio-available nutrients declined with storage. However, in non-sterilized compost this was not the case. This suggests that the indigenous microflora play a significant role in suppression of Salmonella regrowth in composted biosolids. There was a strong negative correlation (-0.85) between the Salmonella inactivation rate and the maturity of compost in non-sterilized compost. The Salmonella inactivation rate was seven times higher in biosolids composting for two weeks as compared to compost stored for two years. This suggests that the antagonistic effect of indigenous microorganisms towards Salmonella declined with compost storage. It was concluded that all composted biosolids had a Salmonella regrowth potential. However, the indigenous microflora significantly reduced this regrowth potential. Long-term storage of compost is not recommended as this may increase the pathogen regrowth potential.

Disinfection↗
PubMed2001

Comparison of the filtration characteristics between attached and suspended growth microorganisms in submerged membrane bioreactor.

An attached growth bioreactor was designed to minimize the effect of suspended microorganisms on membrane fouling in submerged membrane bioreactor. Comparison of mixed liquor from attached and suspended growth systems was made to elucidate major factors giving rise to different filtration characteristics. Unexpectedly, the rate of membrane fouling of the attached growth system was about 7 times higher than that of the suspended growth system despite similar characteristics of soluble fraction from the two reactors. Filtration performance proved to depend on the concentration of mixed liquor suspended solids (MLSS). Better filtration performance with suspended growth was explained by the formation of dynamic membranes with suspended solids. A series of analyses such as hydraulic resistance, specific cake resistance, scanning electron microscope, and atomic force microscope were carried out to elucidate the different filtration characteristics of the two systems.

Biomass↗
PubMed2001

Quantifying filamentous microorganisms in activated sludge before, during, and after an incident of foaming by oligonucleotide probe hybridizations and antibody staining.

Quantitative oligonucleotide probe hybridizations, immunostaining, and a simple foaming potential test were used to follow an incident of seasonal filamentous foaming at the Urbana-Champaign Sanitary District, Northeast Wastewater Treatment Plant. A positive correlation was observed between an increase in foaming potential and the appearance of foam on the surfaces of aeration basins and secondary clarifiers. In addition, during the occurrence of foaming, the mass and activity of Gordonia spp. increased as measured by fluorescence in situ hybridization, antibody staining, and quantitative membrane hybridization of RNA extracts. An increase in Gordonia spp. rRNA levels from 0.25 to 1.4% of total rRNA was observed using quantitative membrane hybridizations, whereas during the same period, the fraction of mixed liquor volatile suspended solids attributed to Gordonia spp. increased from 4% to more than 32% of the total mixed liquor volatile suspended solids. These results indicate that both the activity and biomass level of Gordonia spp. in activated sludge increased relative to the activity aid the biomass level of the complete microbial community during a seasonal occurrence of filamentous foaming. Thus, Gordonia spp. may represent a numerically dominant but metabolically limited fraction of the total biomass, and the role of Gordonia spp. in filamentous foaming may be linked more tightly to the physical presence of filamentous microorganisms than to the metabolic activity of the cells.

Actinomycetales↗
PubMed2001

Acid-stimulated phosphate uptake by activated sludge microorganisms under aerobic laboratory conditions.

Activated sludge inocula taken from five different wastewater treatment plants were grown aerobically under laboratory conditions on mineral salts medium containing either glucose or skimmed milk powder as carbon source. Cultures showed increases of between 50% and 143% in levels of phosphate uptake from the medium when the growth pH was 5.5 rather than 7.5. Of 100 individual sludge microbial isolates studied, 34 demonstrated such acid-stimulated luxury phosphate uptake; the optimum pH for the process was shown to lie between 5.0 and 6.5. Enhanced phosphate removal by these isolates was accompanied by increases of between 2 and 10.5-fold in their polyphosphate content; this was visualised as intracellular inclusions. Acid-stimulated luxury phosphate uptake by environmental microorganisms is a previously-unrecognised phenomenon that may have application in novel technologies for nutrient removal from wastewaters.

Bacteria, Aerobic↗
PubMed1997

Analysis of oil components and hydrocarbon-utilizing microorganisms during laboratory-scale bioremediation of oil-contaminated soil of Kuwait.

A huge amount of oil-contaminated soil remains unremediated in the Kuwait desert. The contaminated oil has the potentiality to cause pollution of underground water and to effect the health of people in the neighborhood. We have been studying bioremediation of Kuwait oil-contaminated soil. Chemical analyses of biodegraded compounds and isolation of petroleum hydrocarbon-decomposing microorganisms were carried out. From the chemical analyses, it was revealed that the decomposed compounds were mainly saturated fractions from alumina column chromatography and that the aromatic fractions were not decomposed well. Isolation of bacteria was carried out for eight kinds of hydrocarbons which are components of crude petroleum (n-hexadecane, 2,6,10,14-tetramethylpentadecane, 1,4-diisopropylbenzene, naphthalene, 1-methylnaphthalene, phenanthrene, anthracene, and perylene). Many of the n-hexadecane- and 2,6,10,14-tetramethylpentadecane-decomposing bacteria were isolated, but aromatic compound-decomposing bacteria were not enriched. It was concluded that the slow decomposition of aromatic compounds was due to the low population of aromatic compound-decomposing bacteria in the Kuwait desert soil.

Bacteria↗
PubMed1999

Microbial degradation of 4-chlorophenol by microorganisms entrapped in carrageenan-chitosan gels.

A new cell immobilization method based on the replacement of KCl by KCl + chitosan as gelling agent was developed. The results showed that through addition of chitosan into gelling agent, the mechanical strength and thermal stability of the carrageenan gel were greatly improved. The new immobilization method was used to entrap a chlorophenol-degrading microorganism. The immobilized microbial cells were applied for chlorophenol biodegradation. The experiments demonstrated that immobilized cells exhibit a higher bioactivity in the degradation of chlorophenol than free cells.

Biodegradation, Environmental↗