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At least 1,369 records · Page 76Linked to original sources
PubMed1996

Potential contribution of optional urease-positive bacteria to idiopathic urinary calcium stone formation. II. Microlith formation kinetics in a fermenter model of the urinary tract infected by optional urease-positive microorganisms.

We investigated the effects of weak to moderate urease hydrolysis by optional urease-positive microorganisms in an artificial urine model enriched with calcium phosphate and calcium oxalate in respect of calcium stone formation. The incubation experiments were performed using a discontinuously running fermenter device to simulate the urinary system. The kinetics of cell division rates, pH and ammonium ion production were measured and correlated to crystallite appearance in the incubation medium. Qualitative analyses of the sediments revealed apatite. Investigations using light microscopy and scanning electron microscopy (SEM) confirmed the matrix effect of bacterial glycoproteins. It was shown that initiation of calcium oxalate stone formation is in all probability equally determined by matrix effects and by heteronuclear crystallization if the urinary tract is infected by optional urease-positive bacteria. When urinary inorganic phosphate is present, calcium phosphate nidi are always initially formed, and may subsequently be coated by calcium oxalate.

Calcium Oxalate↗
PubMed1981

Survival of microorganisms after drying and storage.

Bacteria, yeasts and fungi suspended in a dextran solution were added to ampoules containing strips of filter paper which were dried without vacuum conditions. The ampoules were sealed and stored in the dark at room temperature. Viability counts were made of the original suspension immediately after drying and after storage periods of 3-48 months. Although bacterial cultures of many general did not show much resistance against dry conditions, bacteria of 13 other general had survived well or moderately after 4 years of storage. Most of the dried yeast cultures had survived after this period. Of the 16 fungal genera tested, species of 6 genera exhibited growth after 4 years. Results of this study were compared with those of two other preservation methods by which the same microorganisms were used.

Bacteria↗
PubMed1980

Effects of certain cadmium species on pure and litter populations of microorganisms.

Cadmium inhibition of microorganisms was found to be bacterial and chemical species dependent. E. coli inhibition was a function of the cadmium-ion concentration irregardless of the presence of citrate, a chelator for cadmium that it could not metabolize. Whereas with a Pseudomonas sp. able to metabolize citrate, cadmium inhibition was a function of both the cadmium ion and the presence of citrate. With no citrate, inhibition of this organism occurred only at relatively high cadmium-ion concentrations (above 10(-4) M); when citrate was added to the same cadmium-containing growth medium, inhibition was observed at a 1000 times lower cadmium-ion concentration (i.e., 10(-7) M). This observation is contrary to the classical understanding where a chelate reduces the toxic form of a metal allowing increased growth of the organism. The species of cadmium also differentially inhibited the Douglas fir letter respiration and nitrogen-fixing community activities.

Cadmium↗
PubMed1985

Experimental subcutaneous granulomas in sheep with Dermatophilus-like microorganisms from porcine tonsil.

The pathogenicity of the Dermatophilus-like microorganisms from porcine tonsil and the light and electron microscopic findings were studied with adult ewes. The early lesions were abscessess and advanced ones were granulomas after the subcutaneous inoculation. The granulomas were composed of the central bacterial colonies and the layers of the neutrophils, epithelioid cells and giant cells, and peripheral connective tissues. Epithelioid cells and giant cells were identified by the large euchromatic nuclei, abundant organelles and interdigitation of the blunt pseudopods in the ultrastructure. The lesions were very similar to subcutaneous granulomas in sheep and cattle due to Dermatophilus congolensis (atypical dermatophilosis), actinomycosis and nocardiosis.

Actinomycetales Infections↗
PubMed1982

Biosynthesis of vitamin B12. Different pathways in some aerobic and anaerobic microorganisms.

Radioactivity from [1'-14C]riboflavin was incorporated into the 5,6-dimethylbenzimidazole moiety of Vitamin B12 in the aerobes Bacillus megaterium, Nocardia rugosa and Streptomyces sp. as well as in the aerotolerant anaerobe Propionibacterium freudenreichii, but not in the anaerobe Eubacterium limosum. As recently published for E. limosum, also in the anaerobe Clostridium barkeri radioactivity from [1-14C]glycine and [2-14C]glycine was found in the 5,6-dimethylbenzimidazole moiety, but not in the corrin moiety. The addition of L-[methyl-14C]methionine to C. barkeri led to the labeling of the corrin moiety and the 5,6-dimethylbenzimidazole moiety, showing that the seven "extra" methyl groups in the corrin ring as well as the two methyl groups of the base part originate from this precursor. In Clostridium thermoaceticum, forming the vitamin B12 analog 5-methoxybenzimidazolylcobamide, [1-14C]glycine and [2-14C]glycine were also incorporated into the 5-methoxybenzimidazole moiety, but not into the corrin ring. In E. limosum L-[U-14C]glutamate led to the labeling of the corrin ring of vitamin B12, but not of its base moiety. These results together with data from the literature indicate that a common biosynthetic pathway might exist for the corrinoid biosynthesis in aerobic microorganisms, and in those aerotolerant anaerobes like the Propionibacteria, which form the 5,6-dimethylbenzimidazole moiety of vitamin B12 only under aerobic conditions. They also show that this pathway differs from the pathway found in anaerobic bacteria.

Aerobiosis↗
PubMed1994

Metabolism in hyperthermophilic microorganisms.

Hyperthermophilic microorganisms grow at temperatures of 90 degrees C and above and are a recent discovery in the microbial world. They are considered to be the most ancient of all extant life forms, and have been isolated mainly from near shallow and deep sea hydrothermal vents. All but two of the nearly twenty known genera are classified as Archaea (formerly archaebacteria). Virtually all of them are strict anaerobes. The majority are obligate heterotrophs that utilize proteinaceous materials as carbon and energy sources, although a few species are also saccharolytic. Most also depend on the reduction of elemental sulfur to hydrogen sulfide (H2S) for significant growth. Peptide fermentation involves transaminases and glutamate dehydrogenase, together with several unusual ferredoxin-linked oxidoreductases not found in mesophilic organisms. Similarly, a novel pathway based on a partially non-phosphorylated Entner-Doudoroff scheme has been postulated to convert carbohydrates to acetate, H2 and CO2, although a more conventional Embden-Meyerhof pathway has also been identified in one saccharolytic species. The few hypethermophiles known that can assimilate CO2 do so via a reductive citric acid cycle. Two S(o)-reducing enzymes termed sulfhydrogenase and sulfide dehydrogenase have been purified from the cytoplasm of a hyperthermophile that is able to grow either with or without S(o). A scheme for electron flow during the oxidation of carbohydrates and peptides and the reduction of S(o) has been proposed. However, the mechanisms by which S(o) reduction is coupled to energy conservation in this organism and in obligate S(o)-reducing hyperthermophiles is not known.

Anaerobiosis↗
PubMed1984

[Spoilage of fruit juice by bacilli: isolation and characterization of the spoiling microorganisms].

A Bacillus-strain was isolated from spoiled apple juice. This strain was acidophilic with a growth range between pH 2.5 and 5.5. Lipid analysis demonstrated the occurrence of omega-cyclohexane fatty acids and hopanoids. As these cell constituents have among bacilli been found only in Bacillus acidocaldarius strains, our isolated microorganism seems to be related to this species. Our organism could be a threat to fruit juices during storage at elevated temperatures (greater than or equal to 26 degrees C) because its spores were able to survive pasteurization conditions.

Bacillus↗
PubMed1990

Ultrastructure and distribution of intracellular rickettsia-like microorganisms in various organs of the laboratory-reared adult tick Argas (Persicargas) arboreus (Ixodoidea: Argasidae).

Rod (RS) and coccoid (CS) rickettsia-like microorganisms were found in single and group forms in organs of the laboratory-reared adult ticks Argas (Persicarges) arboreus. RS are distributed in most organs but are mainly concentrated in the salivary glands, mid-gut, and testes. CS single forms were concentrated in the rectal sac, while the group forms were limited to Malpighian tubules and haemocytes of both sexes. The primary oocytes were heavily infected with both forms of CS. No RS or CS were detected in the muscles. Despite the structural differences between RS and CS, they are suggested to be different morphotypes of the same organism.

Animals↗
PubMed1981

The radiation-induced inactivation of microorganisms in non-aqueous suspension: The effect of selected alcohols and paraffins on the radiation sensitivity of aerated Bacillus pumilus spores.

The effect of model compounds comprising alcohols and paraffins on the radiation sensitivity of B pumilus spores has been carried out with the aim of understanding the radiation-induced inactivation of microorganisms when suspended in non-aqueous medium. This study is a prerequisite to the undertaking of radiation sterilization of non-aqueous pharmaceuticals. Spores of B. pumilus E601 mounted on kaolin powder were suspended in the appropriate organic agent and gamma irradiated under oxic conditions. Spores suspended in paraffins displayed increased radiation response over that for aerated buffered suspensions. Values of inactivation constant ranged between 2X and 5X for that buffer. Less pronounced modification of response was obtained for the alcohols. The results reveal a marked tendency for response to increase with decreasing polarity of the suspending fluid. The partial miscibility of the alcohols in water enabled the examining of the transition from the response characteristic of aerated buffered suspensions to those of the spores in pure organic liquids.

Alcohols↗
PubMed1999

Production of tyrosine and other aromatic compounds from phenylalanine by rumen microorganisms.

Rumen contents from three fistulated Japanese native goats fed Lucerne hay cubes (Medicago sativa) and concentrate mixture were collected to prepare the suspensions of mixed rumen bacteria (B), mixed protozoa (P) and a combination of the two (BP). Microbial suspensions were anaerobically incubated at 39 degrees C for 12 h with or without 1 mM of L-phenylalanine (Phe). Phe, tyrosine (Tyr) and other related compounds in both supernatant and microbial hydrolysates of the incubations were analyzed by HPLC. Tyr can be produced from Phe not only by rumen bacteria but also by rumen protozoa. The production of Tyr during 12 h incubation in B (183.6 mumol/g MN) was 4.3 times higher than that in P. One of the intermediate products between Phe and Tyr seems to be p-hydroxyphenylacetic acid. The rate of the net degradation of Phe incubation in B (76.0 mumol/g MN/h) was 2.4 times higher than in P. In the case of all rumen microorganisms, degraded Phe was mainly (> 53%) converted into phenylacetic acid. The production of benzoic acid was higher in P than in B suspensions. Small amount of phenylpyruvic acid was produced from Phe by both rumen bacteria and protozoa, but phenylpropionic acid and phenyllactic acid were produced only by rumen bacteria.

Amino Acids↗
PubMed1978

A screening technique for assessing effects of pesticides on population and activities of non-target soil microorganisms.

A simplified technique for assessing the effect of pesticides on non-target soil microorganisms was developed. Changes in microbial population determined by the dilution plate method, in nitrification by the soil perfusion technique, and in oxygen consumption using a differential respirometer are the only measurements required. A comparison of the effects observed for three pesticides, dieldrin, chlorpyrifos and Vorlex, in three soil types with those produced by an antibiotic, a fungicide, a nitrification inhibitor and steam pasteurization of the soil clearly demonstrate the effectiveness of the simple technique.

Chlorpyrifos↗
PubMed1997

Multicenter clinical comparison of resin-containing bottles with standard aerobic and anaerobic bottles for culture of microorganisms from blood.

In a study comparing the Bactec 9240 (Plus Aerobic/F and Anaerobic/F bottles, containing resins; Becton Dickinson, USA) and the Vital (standard aerobic and anaerobic bottles, with no additives; bioMérieux, France) blood culture systems, 6456 sets of four bottles of 9660 blood cultures submitted were evaluated. There were 531 clinically significant isolates from 795 positive blood cultures. Of the 531 positive blood cultures, 355 were positive in both systems, 141 with the Bactec 9240 alone, and 30 with the Vital alone (p < 0.001); five were not detected by either system. The average time to detection of positive cultures for the matched sets was 10.65 h and 18.41 h by the Bactec 9240 system and the Vital system, respectively. The false-positive rate per bottle was 0.65% in the Bactec 9240 and 0.71% in the Vital. The rate of false-negative pairs (i.e., major errors) was very low (0.12% for the Bactec 9240, 0.19% for the Vital) and not significantly different between the two systems. The striking differences in recovery of microorganisms may be due to the presence of resins in the Bactec medium. However, the observed superiority of the Bactec 9240, even for patients not receiving antibiotics, suggests that resins adsorb other inhibitors present in patients' blood.

Adult↗
PubMed1994

Antimicrobial effect of combinations of EDTA-Tris and amikacin or neomycin on the microorganisms associated with otitis externa in dogs.

Combinations of EDTA-Tris and two aminoglycoside antibiotics (amikacin and neomycin) were tested for synergistic activities against the microorganisms associated with otitis externa in dogs and for the solutions' stability over time. Synergistic activity was observed when EDTA-Tris plus amikacin and EDTA-Tris plus neomycin were tested against Staphylococcus intermedius, Proteus mirabilis, Pseudomonas aeruginosa, and Escherichia coli, but not against Candida albicans. Stability studies over a 3-month period indicated that the test solutions were stable at room temperature and that their antimicrobial activity was maintained.

Amikacin↗
PubMed1992

The effect of long-term exposure to phosphamidon on the ruminal microorganisms and circulating carboxylesterase of Bubalus bubalis.

The effect of long-term exposure to the organophosphate insecticide phosphamidon on the ruminal microorganisms and serum carboxylesterase of buffalo calves was investigated. Oral administration of phosphamidon in doses of 0.25 and 0.5 mg/kg per day for 120 days caused significant inactivation of carboxylesterase activity (16-32%) without eliciting any intoxicating signs apart from mild intermittent diarrhoea in the animals receiving the higher dose. The higher dose also produced a significant reduction in the total number of rumen protozoa (16-24%). However, the insecticide had no discernible effect on the total bacterial count or pH of the rumen liquor.

Administration, Oral↗
PubMed1977

Interorder transfer of mycoplasmalike microorganisms between Drosophila paulistorum and Ephestia kühniella. II. Numbers of MLO and sterility.

A successful attempt was made to culture the mycoplasmalike microorganism causing semispecific hybrid male sterility in Drosophila paulistorum utilizing Ephestia kühniella as the intermediate host. Data gleaned from this passage indicates that the induction of sterility depends upon the quality not the quantity of infectious intracellular symbionts.

Animals↗
PubMed1992

The effect of stress factors on the spontaneous photon emission from microorganisms.

The results of recent work on the photon emission from three yeasts and a bacterium is presented. Both visible region and ultraviolet photon emission is observed; however, no luminescence is observed in the absence of oxygen. The visible region emission is attributed to excited carbonyl groups and excited singlet oxygen dimers formed during the decomposition of lipid hydroperoxides. Possible sources of the ultraviolet photon emission are also examined. The use of microorganisms in the study of ultraweak photon emission and its relation to oxidative, temperature and chemical stress is reviewed and the applications and (or) functions of this photon emission are also discussed.

Bacterial Physiological Phenomena↗