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At least 685 records · Page 38Linked to original sources
PubMed1985

Retrospective analysis of two hundred and twelve cases of bacteremia due to anaerobic microorganisms.

Cases of bacteremia caused by anaerobic microorganisms and occurring during a four year period in a non-selected patient group in a Spanish general hospital were analysed retrospectively. Microbiological data was collected on 212 patients and clinical data on 103 patients. Cases of anaerobic bacteremia represented 8.6% of the total number of cases of bacteremia. Of the 232 anaerobic microorganisms causing bacteremia, gram-negative bacilli were responsible in 113 cases (48.7%), gram-positive bacilli in 92 cases (39.6%), gram-positive cocci in 25 cases (10.7%), and Veillonella spp. in two cases (0.8%). The most important clinical features were fever (64%), anemia (56%), septic shock (22%) and metastatic abscesses (21%). Patients with anaerobic bacteremia were hospitalized for an average of 51.7 days. The overall mortality was 32% and factors associated with poor prognosis were severe underlying disease, nosocomial acquisition, presence of shock, presence of metastatic foci of infection, and absence of adequate surgical drainage. The mortality rate of patients who received adequate antimicrobial therapy was 30% and that of patients who received inadequate treatment or none was 29%. It is concluded that anaerobic bacteremia has a significant rate of morbidity and mortality and that underlying disease and surgical debridement and/or drainage have greater prognostic significance than the use of antimicrobial agents.

Adolescent↗
PubMed1989

[Microorganisms in our food: yesterday, today and tomorrow].

The development of fermented foodstuffs can be considered as one of the greatest achievements of human civilization and goes back thousands of years. It arose from the necessity to conserve foods, to make them more digestible and also more enjoyable. During the centuries man learned by trial and error to conduct the fermentation processes by changing physical and chemical parameters in the basic food ingredients. It took much longer, however, to discover the cause of fermentation processes: only towards the end of the 19th century it was demonstrated, for example, that baker's yeast is the cause of alcoholic fermentation. Through the development of the technique of "pure microbial culture", developed again with yeast, the basis for a controlled use of microbes in food industry was established. The movement from artisan to industrial scale fermentations made necessary a systematic strain development by the "classical" techniques of "mutation, selection and recombination". The modern techniques of genetic engineering have hardly been applied to food microorganisms so far. These methods, which usually have been developed with laboratory strains, would give us the possibility to change or disrupt genes very specifically and even to introduce new genes into established food microorganisms. Some possible applications with the baker's yeast are discussed in this article.

Bacteria↗
PubMed1992

Microorganisms associated with natural fermentation of Prosopis africana seeds for the production of okpiye.

Okpiye is a food condiment prepared by the fermentation of Prosopis africana seeds. The traditional process for the production and microbiological characteristics of the condiment were investigated. During laboratory fermentation that lasted 96 h, the mesquite seeds underwent a natural fermentation that was characterised by the growth of microorganisms to 10(6)-10(8) cfu/g. Several species of bacteria especially B. subtilis, B. licheniformis, B. megaterium, Staphylococcus epidermidis and Micrococcus spp were found to be the most actively involved organisms. However, significant contributions to the microbial ecology were made by Enterobacter cloacae and Klebsiella pneumoniae. Lactobacillus spp were present in low numbers towards the end of the fermentation. The presence of Proteus and Pseudomonas spp in traditional fermented samples demonstrate the variability which may exist in the microflora of individual fermented samples. Variations in the important microbial groups show that Bacillus spp were the most prevalent species and occurred until the end of fermentation. Temperature, pH and titratable acidity varied with time and were influenced by the metabolic activities of the microorganisms.

Bacillus↗
PubMed1993

The threat of multiresistant microorganisms.

Enthusiasm about newly developed antimicrobial agents and disappointment because of the development of resistance have been alternating in the decades since the introduction of antibacterial chemotherapy around 1940. During the last few years several mechanisms of bacterial resistance have been elucidated, and new insights into the genetic basis of multiresistance have been gained. The clinical implications of multiresistance depend on timely recognition of the problem, i.e. knowledge of the epidemiology of multiresistant microorganisms and the availability of alternative drugs. A particular problem arises from the fact that infections with multiresistant microorganisms often occur in the most critically ill patients.

Anti-Bacterial Agents↗
PubMed1996

Production of extracellular beta-mannanases by yeasts and yeast-like microorganisms.

A new screening method for simultaneous detection of endo-beta-1,4-mannanase and endo-beta-1,4-xylanase producing microorganisms is described. Two differently dyed substrates Ostazin Brilliant Red-galactomannan and Remazol Brilliant Blue-xylan were incorporated into the same agar media. Decolorizing of one or both substrates around the cell colonies indicates secretion of the corresponding enzyme(s). The method was used to screen 449 yeasts and yeast-like microorganisms belonging to 68 different genera. The secretion of endo-beta-1,4-mannanases and/or endo-beta-1,4-xylanases was found within 10 genera (42 positive strains out of 261 tested). A low frequency of occurrence of endo-beta-1,4-mannanases was observed within the genera Cryptococcus (1 positive strain out of 15 tested), Geotrichum (1 of 6) and Pichia (1 of 35). The highest frequency of occurrence of endo-beta-1,4-mannanases was found within the genera Stephanoascus (2 of 2) and Aureobasidium (14 of 14). Strains hydrolyzing Ostazin Brilliant Red-galactomannan were cultivated in liquid media containing 1% locust bean gum. The best producers of extracellualr endo-beta-1,4-mannanases were found to be the strains of Aureobasidium pullulans.

Bacteriological Techniques↗
PubMed1999

Oxidative stress in microorganisms--I. Microbial vs. higher cells--damage and defenses in relation to cell aging and death.

Oxidative stress in microbial cells shares many similarities with other cell types but it has its specific features which may differ in prokaryotic and eukaryotic cells. We survey here the properties and actions of primary sources of oxidative stress, the role of transition metals in oxidative stress and cell protective machinery of microbial cells, and compare them with analogous features of other cell types. Other features to be compared are the action of Reactive Oxygen Species (ROS) on cell constituents, secondary lipid- or protein-based radicals and other stress products. Repair of oxidative injury by microorganisms and proteolytic removal of irreparable cell constituents are briefly described. Oxidative damage of aerobically growing microbial cells by endogenously formed ROS mostly does not induce changes similar to the aging of multiplying mammalian cells. Rapid growth of bacteria and yeast prevents accumulation of impaired macromolecules which are repaired, diluted or eliminated. During growth some simple fungi, such as yeast or Podospora spp., exhibit aging whose primary cause seems to be fragmentation of the nucleolus or impairment of mitochondrial DNA integrity. Yeast cell aging seems to be accelerated by endogenous oxidative stress. Unlike most growing microbial cells, stationary-phase cells gradually lose their viability because of a continuous oxidative stress, in spite of an increased synthesis of antioxidant enzymes. Unlike in most microorganisms, in plant and animal cells a severe oxidative stress induces a specific programmed death pathway--apoptosis. The scant data on the microbial death mechanisms induced by oxidative stress indicate that in bacteria cell death can result from activation of autolytic enzymes (similarly to the programmed mother-cell death at the end of bacillary sporulation). Yeast and other simple eukaryotes contain components of a proapoptotic pathway which are silent under normal conditions but can be activated by oxidative stress or by manifestation of mammalian death genes, such as bak or bax. Other aspects, such as regulation of oxidative-stress response, role of defense enzymes and their control, acquisition of stress tolerance, stress signaling and its role in stress response, as well as cross-talk between different stress factors, will be the subject of a subsequent review.

Animals↗
PubMed1982

The role of microorganisms in transformations of sulphite in spruce forest soil.

Transformations of sulphite and the participation of microorganisms were investigated in samples of fermentative (A02) and humus (A03) horizons from a spruce forest. About 80% of sulphite were almost immediately oxidized abiotically to sulphate, less than 1% persisted in the soil for several days and almost 20% were converted to a form not demonstrable as sulphite or sulphate. Microorganisms accelerated the disappearance of less than 10% of the added sulphite.

Bacteria↗
PubMed1991

Effect of the herbicide Bentanex on soil microorganisms and their activity.

The effect of the herbicide Bentanex, especially of its effective component bentazone, on selected soil bacteria and fungi, on their growth and reproduction and on some important physiological activities ensuring a regular nutrient cycle in nature was investigated. Bentazone affected growth and reproduction of soil bacteria and micromycetes in dependence on the concentration and species of the microorganism. Physiological and biochemical activities of bacteria with respect to nitrogen fixation, nitrification and CO2 production were negatively influenced by high concentrations of the herbicide. These concentrations were used to observe the effect on selected activities of soil microorganisms and were much higher than those actually used in agriculture.

Bacteria↗
PubMed1993

Activity of the AIB factor observed in prokaryotic and eukaryotic microorganisms.

Streptomyces cinnamonensis produces a new substance named AIB (for anti-isobutyrate) factor which, on a solid medium, efficiently counteracts toxic concentrations not only of isobutyrate but also of other salts of short-chain monocarboxylic acids. In the present study we demonstrate that the AIB factor activity is widely spread because this effect was positively detected in 25 of 31 randomly chosen microorganisms (streptomycetes, ascomycetes, zygomycetes and basidiomycetes). The AIB factor produced by the tested microorganisms on an agar media allows for germination, growth, and sporulation of the testing Streptomyces coelicolor on an agar medium containing 20 mmol/L acetate, propionate, butyrate, isobutyrate, valerate, isovalerate, and 2-methylbutyrate. The activity of the AIB factor from different sources towards these substances differs.

Ascomycota↗
PubMed1997

Merits of secretion of heterologous proteins from industrial microorganisms.

The heterologous expression of proteins is without doubt one of the most fascinating applications of the recombinant DNA technique. Despite clear successes many attempts to produce a certain protein in a heterologous host cell have met with technical difficulties. Secretion from cells has been used as a solution to overcome the intracellular formation of inactive protein. Microorganisms with a history of use in the fermentation industry exhibit clear advantages over the frequently used Escherichia coli as host cells for secreted products. Interleukin-3, chymosin and phytase are examples of commercial products that are produced efficiently with the aid of industrial microorganisms.

6-Phytase↗
PubMedDate not supplied

Biological deodorization of dimethyl sulfide using different fabrics as the carriers of microorganisms.

Biological deodorization of dimethyl sulfide (DMS) was studied using nine unwoven fabrics as the carriers of microorganisms in a laboratory-scale deodorizing system. The activated carbon fabric FN-200CF-15 was the best packing material compared with other packing materials used, on the basis of removal rate. The maximum removal rate (Vm), evaluated by using Michaelis-Menten equation, was 2.28 g-S.kg-dry fab.-1.day-1 in this fabric biofilter. The critical load of DMS in this fabric biofilter was dependent on space velocity (SV), determined as 0.78 and 0.66 g-S.kg-dry fab.-1 at SV 100 and 150 h-1, respectively. Strain IM1 isolated from the carbon fabric FN-200CF-15 biofilter in modified Waksman (MW) medium successfully degraded DMS as well as hydrogen sulfide (H2S), methanethiol (MT), and dimethyl disulfide (DMDS) in batch test. The DMS removal rates (g-S.cell-1.h-1) by this strain measured in batch culture and calculated in FN-200CF-15 biofilter by the cell numbers appeared in MW medium were found almost equal, indicating that strain IM1 may be the dominant microorganism in this biofilter.

Air Pollution↗
PubMed2003

LC-MS analysis in the aquatic environment and in water treatment technology--a critical review. Part II: Applications for emerging contaminants and related pollutants, microorganisms and humic acids.

Environmental contaminants of recent concern are pharmaceuticals, estrogens and other endocrine disrupting chemicals (EDC) such as degradation products of surfactants, algal and cyanobacterial toxins, disinfection by-products (DBPs) and metalloids. In addition, pesticides (especially their transformation products), microorganisms, and humic substances (HS), in their function as vehicles for contaminants and as precursors for by-products in water treatment, traditionally play an important role. The present status of the application of LC-MS techniques for these water constituents are discussed and examples of application are given. Solid-phase extraction with various non-selective materials in combination with liquid chromatography (LC) on reversed-phase columns have been the most widely used methods for sample preconcentration and separation for different compound classes like pesticides, pharmaceuticals or estrogens. Electrospray ionization (ESI) and atmospheric pressure ionization (APCI) are the most frequently used ionization techniques for polar and ionic compounds, as well as for less polar non-ionic ones. The facilities of LC-MS have been successfully demonstrated for different compound classes. Polar compounds from pharmaceuticals used as betablockers, iodinated X-ray contrast media, or estrogens have been determined without derivatization down to ultratrace concentrations. LC-MS can be viewed as a prerequisite for the determination of algal and cyanobacterial toxins and the homologues and oligomers of alkylphenol ethoxylates and their metabolites. Tandem mass spectrometric techniques and the use of diagnostic ions reveal their usefulness for compound-class specific screening and unknown identification, and are also valid for the analysis of pesticides and especially for their transformation products. Structural information has been gained by the application of LC-MS methods to organometallic species. New insights into the structural variety of humic substances have been made possible by FT-ICR-MS due to its ultrahigh mass resolution. Finally, exciting possibilities for rapid detection and identification of microorganisms have been made possible by MALDI and LC-MS methods.

Bacteria↗
PubMed2005

Microorganisms in inorganic chemical analysis.

There are innumerable strains of microbes (bacteria, yeast and fungi) that degrade or transform chemicals and compounds into simpler, safer or less toxic substances. These bioprocesses have been used for centuries in the treatment of municipal wastes, in wine, cheese and bread making, and in bioleaching and metal recovery processes. Recent literature shows that microorganisms can be also used as effective sorbents for solid phase extraction procedures. This review reveals that fundamental nonanalytical studies on the parameters and conditions of biosorption processes and on metal-biomass interactions often result in efficient analytical procedures and biotechnological applications. Some selected examples illustrate the latest developments in the biosorption of metals by microbial biomass, which have opened the door to the application of microorganisms to analyte preconcentration, matrix separation and speciation analysis.

Bacteria↗
PubMed2005

Enrichment and detection of microorganisms involved in direct and indirect methanogenesis from methanol in an anaerobic thermophilic bioreactor.

To gain insight into the microorganisms involved in direct and indirect methane formation from methanol in a laboratory-scale thermophilic (55 degrees C) methanogenic bioreactor, reactor sludge was disrupted and serial dilutions were incubated in specific growth media containing methanol and possible intermediates of methanol degradation as substrates. With methanol, growth was observed up to a dilution of 10(8). However, when Methanothermobacter thermoautotrophicus strain Z245 was added for H2 removal, growth was observed up to a 10(10)-fold dilution. With H2/CO2 and acetate, growth was observed up to dilutions of 10(9) and 10(4), respectively. Dominant microorganisms in the different dilutions were identified by 16S rRNA-gene diversity and sequence analysis. Furthermore, dilution polymerase chain reaction (PCR) revealed a similar relative abundance of Archaea and Bacteria in all investigated samples, except in enrichment with acetate, which contained 100 times less archaeal DNA than bacterial DNA. The most abundant bacteria in the culture with methanol and strain Z245 were most closely related to Moorella glycerini. Thermodesulfovibrio relatives were found with high sequence similarity in the H2/CO2 enrichment, but also in the original laboratory-scale bioreactor sludge. Methanothermobacter thermoautotrophicus strains were the most abundant hydrogenotrophic archaea in the H2/CO2 enrichment. The dominant methanol-utilizing methanogen, which was present in the 10(8)-dilution, was most closely related to Methanomethylovorans hollandica. Compared to direct methanogenesis, results of this study indicate that syntrophic, interspecies hydrogen transfer-dependent methanol conversion is equally important in the thermophilic bioreactor, confirming previous findings with labeled substrates and specific inhibitors.

Acetates↗
PubMed2006

Abundance, diversity, and dynamics of viruses on microorganisms in activated sludge processes.

We examined the abundance of viruses on microorganisms in activated sludge and the dynamics of their community structure. Direct counting with epifluorescence microscopy and pulsed-field gel electrophoresis (PFGE) were applied to 20 samples from 14 full-scale wastewater treatment plants (wwtps) treating municipal, industrial, or animal wastewater. Furthermore, to observe the dynamics of viral community structure over time, a laboratory-scale sequencing batch reactor was operated for 58 days. The concentrations of virus particles in the wwtps, as quantified by epifluorescence microscopy, ranged from 4.2 x 10(7) to 3.0 x 10(9) mL-1. PFGE, improved by the introduction of a higher concentration of Tris-EDTA buffer in the DNA extraction step, was successfully used to profile DNA viruses in the activated sludge. Most of the samples from different wwtps commonly had bands in the 40-70 kb range. In the monitoring of viral DNA size distribution in the laboratory-scale reactor, some bands were observed stably throughout the experimental period, some emerged during the operation, and others disappeared. Rapid emergence and disappearance of two intense bands within 6 days was observed. Our data suggest that viruses--especially those associated with microorganisms--are abundant and show dynamic behavior in activated sludge.

Animals↗
PubMed2002

Metabolic engineering towards biotechnological production of carotenoids in microorganisms.

Carotenoids are important natural pigments produced by many microorganisms and plants. Traditionally, carotenoids have been used in the feed, food and nutraceutical industries. The recent discoveries of health-related beneficial properties attributed to carotenoids have spurred great interest in the production of structurally diverse carotenoids for pharmaceutical applications. The availability of a considerable number of microbial and plant carotenoid genes that can be functionally expressed in heterologous hosts has opened ways for the production of diverse carotenoid compounds in heterologous systems. In this review, we will describe the recent progress made in metabolic engineering of non-carotenogenic microorganisms for improved carotenoid productivity. In addition, we will discuss the application of combinatorial and evolutionary strategies to carotenoid pathway engineering to broaden the diversity of carotenoid structures synthesized in recombinant hosts.

Bacteria↗
PubMed2005

A novel membrane bioreactor enhanced by effective microorganisms for the treatment of domestic wastewater.

The activated sludge membrane bioreactor (MBR) has been shown to have some advantages for the processing and reclamation of domestic wastewater. We hypothesized that certain microorganisms, chosen for their abilities to decompose the chemical components of raw sewage, would, when coupled with the MBR, significantly improve the stability and efficiency of this system. We selected environmental bacterial strains which oxidize ammonia and nitrites and produce protease, amylase, and cellulase for the development and testing of a novel biologically enhanced MBR (eMBR). We compared the eMBR with the activated sludge MBR. With the eMBR, the average values of effluent quality were: chemical oxygen demand (COD), 40 mg/l(average efficiency of removal 90.0%); and NH(4) (+)-N, 0.66 mg/l(average efficiency of removal 99.4%). Effluent qualities met the standard and were stable during the entire 90 days of this study. For the activated sludge MBR, the COD removal rate was 91.7%, and the NH(4) (+)-N removal (94.8%) was less than that of the eMBR. Start-up time for the eMBR was only 24-48 h, much shorter than the 7-8 days required to initiate function of the standard MBR. The biomass concentrations of total heterotrophic bacteria and autotrophic bacteria in the eMBR did not fluctuate significantly during the course of the study. Various kinds of microorganisms will establish an ecological balance in the reactor. Compared with the activated sludge MBR, the eMBR not only produced an excellent and stable quality of effluent but also resulted in a shorter time to start-up and significantly improved the efficiency of NH(4) (+)-N removal.

Bacteria↗
PubMed2005

The use of microorganisms for the formation of metal nanoparticles and their application.

Nanomaterials are at the leading edge of the rapidly developing field of nanotechnology. The development of reliable experimental protocols for the synthesis of nanomaterials over a range of chemical compositions, sizes, and high monodispersity is one of the challenging issues in current nanotechnology. In the context of the current drive to develop green technologies in material synthesis, this aspect of nanotechnology is of considerable importance. Biological systems, masters of ambient condition chemistry, synthesize inorganic materials that are hierarchically organized from the nano- to the macroscale. Recent studies on the use of microorganisms in the synthesis of nanoparticles are a relatively new and exciting area of research with considerable potential for development. This review describes a brief overview of the current research worldwide on the use of microorganisms in the biosynthesis of metal nanoparticles and their applications.

Bacteria↗