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 991 records · Page 55Linked to original sources
PubMed1973

Detection and preliminary studies on dextranase-producing microorganisms from human dental plaque.

An enriched nutrient agar medium containing blue dextran has been utilized for the detection of dextranase-producing microorganisms in human dental plaque. When compared with the total viable anaerobic plaque flora, the proportion of these microbes in supragingival plaque from different individuals varied over a wide range. Preliminary characterization of some of the dextranase-producing microorganisms revealed a heterogeneous mixture of cell types with varying morphological and biochemical characteristics. Several bacterial isolates were tentatively identified as being members of the genus Actinomyces. An additional isolate appeared to belong to the genus Bacteroides. The dextran-degrading enzymes produced by these bacteria are extracellular, and a cell-free preparation from one of the isolates has been shown to cause extensive endohydrolytic cleavage of high-molecular-weight dextrans.

Actinomyces↗
PubMed1974

Properties of alpha-aminoisobutyric acid transport in a thermophilic microorganism.

Uptake of alpha-aminoisobutyric acid (AIB) by a leucine-tyrosine auxotroph of a thermophilic microorganism starved for leucine was studied. AIB was taken up by the cells against a substantial concentration gradient (300:1) and was present there in a free and unchanged form. Various energy inhibitors and sulfhydryl reagents strongly inhibited the accumulation of AIB. AIB uptake obeyed saturation kinetics, and the Lineweaver-Burk plot is characterized by a biphasic curve. AIB most probably shares a common transport system(s) with alanine, serine, and glycine. A mutant defective in l-alanine uptake was isolated by using the suicide effect due to accumulation of the tritiated substrate. The mutant also exhibited impaired transport activity towards AIB, glycine, and l-serine, but not to phenylalanine or valine. The transport of AIB, glycine, l-alanine, and l-serine was induced by d-alanine (5 x 10(-3) M) during growth in a succinate- and ammonia-containing medium. De novo protein synthesis was required for the induction of AIB transport; the induction was inhibited when growth occurred in glucose-containing media. The apparent differential rate of synthesis of the AIB transport system was decreased considerably in glucose-grown cells as compared to succinate-grown cells. A common genetic basis of either the regulatory or structural nature for the transport of AIB, alanine, glycine, and serine in a thermophilic microorganism is suggested.

Amino Acids↗
PubMed1962

Accumulation of S-adenosylmethionine by microorganisms.

Gawel, L. J. (Oregon State University, Corvallis), J. R. Turner, and L. W. Parks. Accumulation of S-adenosylmethionine by microorganisms. J. Bacteriol. 83:497-499. 1962.-A series of microorganisms selected to represent a variety of microbial types was cultured under conditions conducive to the formation of S-adenosylmethionine. Of the organisms tested, only Saccharomyces cerevisiae accumulated measurable amounts of S-adenosylmethionine. Pseudomonas fluorescens and Escherichia coli accumulate 5'-methylthioadenosine under the same conditions.

Deoxyadenosines↗
PubMed1962

Binding of steroids by microorganisms.

Hartman, Ronald E. (American Cyanamid Co., Pearl River, N.Y.) and Chester E. Holmlund. Binding of steroids by microorganisms. J. Bacteriol. 84:1254-1259. 1962.-Certain microorganisms, particularly higher fungi, are able to bind steroids. The steroids can be recovered by solvent extraction only after lyophilization of the cultures. There appears to be a relationship between steroid structure and avidity for the microbial-binding component from Penicillium canescens. Sterols which possess a long side chain and a 3beta-hydroxy-5-ene group are particularly susceptible to microbial binding. The sterol-binding component of P. canescens is released by rupture of the cells. After liberation from the intact cells, it appears to be highly unstable in the presence of other cellular constituents.

Bacteria↗
PubMed1963

TEMPERATURE-GRADIENT INCUBATOR FOR DETERMINING THE TEMPERATURE RANGE OF GROWTH OF MICROORGANISMS.

Elliott, R. Paul (U.S. Department of Agriculture, Albany, Calif.). Temperature-gradient incubator for determining the temperature range of growth of microorganisms. J. Bacteriol. 85:889-894. 1963.-The temperature-gradient incubator consists of an aluminum bar with troughs for media, with controlled temperatures at each end, and with insulation to prevent heat transfer. The resulting linear temperature gradient provides a means for determining minimal or maximal growth temperatures of microorganisms in any desired range and at any desired gradient. The operation of the incubator is unaffected by line-voltage variations or by ambient temperature. Media do not dehydrate seriously even during prolonged periods of operation. The incubator can be used to determine water activity of media by an adjustment to permit partial freezing. Either thermocouples or thermistors may be used to measure temperatures.

Equipment and Supplies↗
PubMed1963

CLASSIFICATION OF MICROORGANISMS BY ANALYSIS OF CHEMICAL COMPOSITION. I. FEASIBILITY OF UTILIZING GAS CHROMATOGRAPHY.

Abel, K. (Melpar, Inc., Falls Church, Va.), H. deSchmertzing, and J. I. Peterson. Classification of microorganisms by analysis of chemical composition. I. Feasibility of utilizing gas chromatography. J. Bacteriol. 85:1039-1044. 1963.-The feasibility of utilizing gas chromatography as a sensitive and rapid method for the analysis of lipids as a natural basis for the classification of microorganisms by chemical composition was investigated. The lipids were extracted and transesterified to component carboxylic acid methyl esters in a single step, after which the methyl esters were resolved by gas chromatography to provide distinctive chromatographic elution patterns. Similarities in the lipid carboxylic acid distribution were noted among selected species of the family Enterobacteriaceae, and significant differences were noted among selected families of the class Schizomycetes.

Bacillus anthracis↗
PubMed1963

FREE RADICAL FORMATION AND SURVIVAL OF LYOPHILIZED MICROORGANISMS.

Heckly, Robert J. (University of California, Berkeley), R. L. Dimmick, and J. J. Windle. Free radical formation and survival of lyophilized microorganisms. J. Bacteriol. 85:961-966. 1963.-A correlation between death and spontaneous free radical production, measured by an increase in the relative electron paramagnetic resonance (EPR) signal, was shown to exist for several species of microorganisms stored in the freezedried state, but the relationship between the free radical concentration and number of dead cells was not a simple proportion. Lactose added to Sarcina lutea reduced radical production and increased stability when dry preparations were stored in air. Death and free radical formation were more extensive when lyophilized Streptococcus lactis cultures were stored in air than in vacuum. Free radicals were also produced by dry yeast. Few, if any, free radicals were produced by bacteria or yeast stored in vacuum. It was shown that the observed free radical production was not caused by exposure to light. The EPR signal produced by dry Serratia marcescens decreased rapidly when cells were exposed to a humid atmosphere but the EPR signal slowly increased after cells were redried and exposed to oxygen.

Bacteria↗
PubMed1963

DIALYSIS FLASK FOR CONCENTRATED CULTURE OF MICROORGANISMS.

Gerhardt, Philipp (The University of Michigan, Ann Arbor), and D. M. Gallup. Dialysis flask for concentrated culture of microorganisms. J. Bacteriol 86:919-929. 1963.-A twin-chambered dialysis flask was designed with a supported membrane clamped between a reservoir of medium in the bottom and a small volume of culture above, the unit being mounted on a shaking machine to provide aeration and agitation. The performance of different dialysis membranes and membrane filters was compared in glucose-diffusion and bacterial-culture tests. Some of the variables in dialysis culture were assessed and the growth response was characterized, with Serratia marcescens as the test organism. The general usefulness and concentrating effect of dialysis culture were demonstrated in trials with 16 representative types of microorganisms. Dialysis culture was shown to be especially suitable for producing dense populations of cells or their macromolecular products in an environment free from complex medium constituents, for removing toxic products that limit growth or fermentation, and for supplying oxygen by diffusion without the damage from usual aeration procedures.

Bacteriological Techniques↗
PubMed1963

STARCH GEL ELECTROPHORESIS OF A FRACTION OF CERTAIN OF THE PLEUROPNEUMONIA-LIKE GROUP OF MICROORGANISMS.

Fowler, Richard C. (George Washington University School of Medicine, Washington, D.C.), Don W. Coble, Norman C. Kramer, and Thomas McP. Brown. Starch gel electrophoresis of a fraction of certain of the pleuropneumonia-like group of microorganisms. J. Bacteriol. 86:1145-1151. 1963.-Starch gel electrophoresis is suggested as a means of further characterizing strains of the pleuropneumonia-like group of microorganisms (PPLO), defined herein as including both the various "L" forms of bacteria and the Mycoplasmataceae. The techniques used may be varied to "select" other groups of proteins or classes of compounds (e.g., glycoproteins, lipoproteins, and enzymes). Only the results by starch gel electrophoresis on the soluble portion of sonically treated, washed cultures, grown in a pancreatic digest of beef heart enriched with bovine serum, are reported. As yet, differences appear more significant than similarities among the electrophoretically separable proteins. The demonstration of characteristic protein patterns for each strain studied suggests possibilities of further dividing serological groups into sero-logically distinct subtypes. Tentative migration values (E(f)) have been assigned to the protein bands for convenience in designation. Numerous interrelationships are thereby suggested.

Animals↗
PubMed1965

Immunochemical studies on alpha-amylase. 3. Immunochemical relationships among amylases from various microorganisms.

Sirishinha, Stitaya (University of Rochester School of Medicine and Dentistry, Rochester, N.Y.), and Peter Z. Allen. Immunochemical studies on alpha-amylase. III. Immunochemical relationships among amylases from various microorganisms. J. Bacteriol. 90:1120-1128. 1965.-Immunochemical relationships among amylases obtained from a selected group of microorganisms were examined, and a cross-reaction was detected between the alpha-amylases of Bacillus stearothermophilus and B. subtilis. Immunodiffusion and quantitative precipitin studies, as well as cross-neutralization tests, indicate that B. stearothermophilus alpha-amylase reacts with a portion of antibody present in antisera to crystalline B. subtilis alpha-amylase. Amylases from these two species thus have some aspects of structure in common. Limited data obtained by immunodiffusion suggest that groupings which confer cross-reactivity to the B. stearothermophilus enzyme are lost after exposure to mercaptoethanol in the presence of ethylenediamine-tetraacetate, followed by treatment with iodoacetamide. With the antisera employed and within the concentration range examined, no immunochemical cross-reaction was observed among amylases from Aspergillus oryzae, B. subtilis, B. polymyxa, B. macerans, Pseudomonas saccharophila, and Euglena sanguinis. Immunoelectrophoresis of partially purified B. stearothermophilus alpha-amylase by use of antiserum to the crude enzyme, together with localization of amylase activity in immunoelectrophoretic plates, suggests that B. stearothermophilus alpha-amylase is antigenic in the rabbit.

Amylases↗
PubMed1966

Enzymatic studies of pure cultures of rumen microorganisms.

Joyner, A. E., Jr. (University of California, Davis), and R. L. Baldwin. Enzymatic studies of pure cultures of rumen microorganisms. J. Bacteriol. 92:1321-1330. 1966.-The activities of enzymes representing the major pathways of carbohydrate metabolism and anaerobic electron transport in cell-free extracts of whole rumen contents have been reported. The effects of diet upon the activities of several enzymes suggested that enzymatic measurements might prove useful for the study of rumen metabolism. In the present study, the distribution and characteristics of aldolase, succinate dehydrogenase, glutamate dehydrogenase, lactyl-coenzyme A dehydrase, lactate dehydrogenase, and other enzymes were measured in cell-free extracts of pure cultures of Ruminococcus flavefaciens, R. albus, Bacteroides succinogenes, B. ruminicola, B. amylophilus, Butyrivibrio fibrisolvens, Peptostreptococcus elsdenii, Streptococcus bovis, and Selenomonas ruminantium. Some enzymes were widely distributed (aldolase, glutamate dehydrogenase), whereas others were observed in one or two species (lactyl-coenzyme A dehydrase). The cofactor requirements and kinetic characteristics of enzymes varied considerably with species. Enzymes that vary with species might be employed as indices for estimating the activities of various groups of microorganisms in whole rumen contents.

Animals↗
PubMed1981

Comparison of acridine orange and Gram stains for detection of microorganisms in cerebrospinal fluid and other clinical specimens.

Acridine orange, a fluorochrome strain, is potentially superior to the Gram stain in the direct microscopic examination of clinical specimens because it gives striking differential staining between bacteria and background cells and debris. Its value in clinical laboratories was evaluated by testing 209 cerebrospinal fluids and 288 other body fluids, tissues, and exudates by both techniques. Smears were made in duplicate, fixed with methanol, stained, and examined without knowledge of the result of the companion smear or culture. Overall, acridine orange was slightly more sensitive than the Gram stain (acridine orange, 59.9%; Gram stain, 55.8%) and equally specific in detecting microorganisms. One smear was falsely positive by the Gram stain; none was falsely positive by the acridine orange stain. We conclude that acridine orange staining is a sensitive method for screening clinical specimens and reviewing selected specimens that are purulent, but negative by the Gram stain. Bloody fluids, thick exudates, and other normally difficult-to-read specimens were easily and quickly examined. We recommend, however, that positive smears be reexamined with the Gram stain to confirm the result and determine the Gram reaction of the microorganisms.

Acridine Orange↗
PubMed1982

Rapid method for simultaneous detection of the arginine dihydrolase system and amino acid decarboxylases in microorganisms.

A specific procedure has been developed for the detection of the first two enzymes involved in the arginine dihydrolase system and the detection of the decarboxylases of arginine, glutamic acid, histidine, lysine, ornithine, phenylalanine, tryptophan, and tyrosine. A loopful of growth of each organism from dihydrolase-decarboxylase induction agar medium (or broth) was washed and incubated separately with 0.2-ml samples of three test media supplemented with different amino acids. Each spent test medium was dansylated, and the dansyl derivatives were separated by two-dimensional thin-layer chromatography on polyamide sheets. The end products (citrulline, ornithine, gamma-amino-n-butyric acid, and amines) produced during incubation were estimated by comparing the fluorescent intensities of end products from the spent test media and of the corresponding parent amino acids from test medium controls after thin-layer chromatography. The method is reproducible, requiring incubation of an organism in three test media for 1 h for simultaneous detection of the first two enzymes involved in the arginine dihydrolase system and of eight amino acid decarboxylases. This method has been successfully applied to gram-positive and gram-negative microorganisms and also to Mycoplasmatales. It could simplify and improve the accuracy of the corresponding biochemical tests performed in clinical laboratories for the identification and differentiation of microorganisms, and it may prove particularly useful for the differentiation of species of Pseudomonas and Mycoplasma.

Bacteria↗
PubMed1986

Two-dimensional thin-layer chromatography for the specific detection of hippurate hydrolysis by microorganisms.

Glycine, one of the end products of hippurate hydrolysis by microorganisms, was detected by a rapid, specific technique utilizing two-dimensional thin-layer chromatography. A loopful of growth of each organism from its suitable agar medium was washed, suspended, and incubated with 0.1% sodium hippurate for 30 min at 37 degrees C. The supernatant of the incubated suspension from each organism was then dansylated, and the dansyl derivatives were separated by two-dimensional thin-layer chromatography on polyamide sheets. Glycine, a product of hippurate hydrolysis, was detected under UV light. This technique does not require prolonged incubation and was found to be more specific and reliable than the standard ninhydrin reaction. In addition, it is inexpensive and can be easily conducted in a clinical microbiological reference laboratory. By this method, 100% (22/22) of Campylobacter jejuni and 0% (0/9) of Campylobacter coli reference strains were positive. In addition, 100% (13/13) of group B streptococci, 100% (24/24) of group D streptococci, and 90% (18/20) of Gardenerella vaginalis clinical isolates were positive for hippurate hydrolysis. This method is useful for the identification to the species level of Campylobacter organisms and the biotyping of Gardnerella organisms and for the detection of hippurate hydrolysis by unknown microorganisms.

Bacteria↗
PubMed1987

Improved method for recovery of peritonitis-causing microorganisms from peritoneal dialysate.

The efficacy of recovery of peritonitis-causing microorganisms from peritoneal dialysate fluid by using the Septi-Chek blood culture system (Roche Diagnostics, Div. Hoffmann-La Roche Inc., Nutley, N.J.) was compared with those of other conventional techniques, such as the 20-ml culture and the filtration methods. The recovery of microorganisms by using the Septi-Chek system was found to be as effective as the filtration of 250 ml of dialysate that used a modified Millipore filtration technique (Millipore Corp., Bedford, Mass.). Both methods were found to be superior to the 20-ml culture method. We suggest using the Septi-Chek method as the standard protocol for the culture of dialysate as a relatively inexpensive and labor-saving recovery technique.

Bacteria↗
PubMed1991

Slot immunoblot assay for detection and quantitation of periodontal disease-associated microorganisms in dental plaque.

A rapid method for qualitative and quantitative detection of specific oral microorganisms from subgingival dental plaque is described. Plaque samples were suspended in phosphate-buffered saline containing protease inhibitors and 0.5% formaldehyde, briefly sonicated to disperse bacterial aggregates, and applied to nitrocellulose membranes in a slot blot manifold. Subsequent incubations with species-specific rabbit antibody and anti-rabbit antibody-alkaline phosphatase conjugate and development with BCIP-NBT substrate resulted in an easily discernible, permanent stain being deposited at the sample application site. Comparison with known concentrations of pure, cultured microorganisms applied to the same membranes permitted qualitative or semiquantitative plaque characterization by visual inspection. Analysis of the blots with a computer-linked flatbed scanner provided quantitative data on microbial content. The reproducibility of the results (standard error of the mean, less than 10%) obtained with slot immunoblotting greatly exceeded that of the results obtained with immunofluorescence analysis (standard error of the mean, greater than 57%). Because it is versatile, rapid, sensitive, reproducible, permanent, and relatively inexpensive, slot immunoblotting lends itself to use in large-scale investigations for the detection and quantitation of specific microbial species.

Adult↗
PubMed1994

Bacterial vaginosis and vaginal microorganisms in idiopathic premature labor and association with pregnancy outcome.

The vaginal microflora of 49 women in idiopathic preterm labor was compared with that of 38 term controls to determine whether the presence of bacterial vaginosis (BV) and/or specific microorganisms would influence the rate of preterm delivery. Demographic factors, pregnancy outcome, and reproductive history were also studied. BV, as defined by the presence of clue cells in a vaginal wet mount and characteristic microbial findings in a stained vaginal smear and vaginal culture, was more common in women with preterm labor and delivery than in controls (P < 0.01). The condition, diagnosed in 41% of women who had both preterm labor and delivery (n = 22) and in 11% each of women who had preterm labor but term delivery (n = 27) and controls, was associated with a 2.1-fold risk (95% confidence intervals, 1.2 to 3.7) for preterm birth prior to 37 weeks of gestation. BV was associated with low birth weight. Of 49 women with preterm labor, 67% (8 of 12) of women with BV were delivered of low-birth-weight neonates (< 2,500 g) compared with 22% (8 of 37) of women without the condition (P < 0.0005). The presence of hydrogen peroxide-producing facultative Lactobacillus spp. was strongly negatively associated with both preterm delivery and BV. BV-associated microorganisms, i.e., Mobiluncus, Prevotella, and Peptostreptococcus species, Porphyromonas asaccharolytica, Fusobacterium nucleatum, Mycoplasma hominis, and high numbers of Gardnerella vaginalis were significantly associated with preterm delivery; all species also strongly associated with BV (P = 0.0001 for each comparison). Mobiluncus curtisii and Fusobacterium nucleatum were recovered exclusively from women with preterm delivery. Our study clearly indicates that BV and its associated organisms are correlated with idiopathic premature delivery.

Adult↗
PubMed1999

Rapid identification of nine microorganisms causing acute respiratory tract infections by single-tube multiplex reverse transcription-PCR: feasibility study.

Acute respiratory tract infections (ARIs) are leading causes of morbidity and, in developing countries, mortality in children. A multiplex reverse transcription-PCR (RT-PCR) assay was developed to allow in one test the detection of nine different microorganisms (enterovirus, influenza A and B viruses, respiratory syncytial virus [RSV], parainfluenzaviruses type 1 and type 3, adenovirus, Mycoplasma pneumoniae, and Chlamydia pneumoniae) that do not usually colonize the respiratory tracts of humans but, if present, must be assumed to be the cause of respiratory disease. Clinical samples from 1,118 children admitted to the Department of Pediatrics because of an ARI between November 1995 and April 1998 were used for a first clinical evaluation. Detection of one of the microorganisms included in the assay was achieved for 395 of 1,118 (35%) clinical samples, of which 37.5% were RSV, 20% were influenza A virus, 12.9% were adenovirus, 10.6% were enterovirus, 8.1% were M. pneumoniae, 4.3% were parainfluenzavirus type 3, 3.5% were parainfluenzavirus type 1, 2.8% were influenza B virus, and 0.2% were C. pneumoniae. Seasonal variations in the rates of detection of the different organisms were observed, as was expected from the literature. The levels of concordance with the data obtained by commercially available enzyme immunoassays were 95% for RSV and 98% for influenza A. The results show that the multiplex RT-PCR-enzyme-linked immunosorbent assay is a useful and rapid diagnostic tool for the management of children with ARI. Studies of the overall benefit of this method with regard to the use of antibiotics, the use of diagnostic procedures including additional microbiological tests, and hospitalization rate and duration are warranted.

Acute Disease↗