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PubMedDate not supplied

[Use of a method of concentrating microorganisms in an electric field in the search for life in Mars].

The paper describes a technique of concentrating microorganisms from filtrates obtained from mixtures of the Martian ground analogs and desert soil using electroretention on polarizable carriers (sterilized cotton wool or gauze). The degree of retention can reach 99.9% at a field intensity of 50 V/cm and a flow rate of 0.5 ml/min. A high concentration of microorganisms in a suspension can be reached when the current is switched off and a small volume of the fresh nutrient medium is passed through the suspension.

Extraterrestrial Environment↗
PubMedDate not supplied

[Synthesis and hydrolysis lipids in microorganisms (a review)].

The review presents current concepts of the synthesis and hydrolysis of phospholipids and triglycerides of microorganisms. The paper discusses differences in the synthesis of phospholipids in micro- and macroorganisms as well as properties an reversal of action of lipases (triglyceride hydrolases) in microorganisms.

Bacteria↗
PubMedDate not supplied

[Method of calculating the specific growth rate of microorganisms by measurements of the substrate or product concentration].

A procedure and formulae are proposed for calculating the specific rate of microbial growth; these are based on measuring the concentration of either a limiting substrate or a product involved in the growth of a microorganism. Only the concentrations of a substrate (S) or a product (P) are determined periodically in the course of the cultural growth whereas the biomass yield (chi) in the medium is established only after long time intervals. The proposed equations may be used for controlling the specific growth rate in large-scale processes by the concentration of a product (or a substrate) using a computer, as well as in laboratory studies of mu as a function of the conditions for growth of slowly growing microorganisms.

Bacteria↗
PubMedDate not supplied

[Isolation and characterization of microorganisms with mannanase activity].

Twenty-three strains of soil microorganisms synthetizing extracellular mannanase were isolated on the medium containing baker's yeast mannan as the sole carbon source. Ten most active strains were identified with respect to their genera. These microorganisms proved capable to hydrolyze mannans, whose mannopyranose units were bound by alpha-1,2-and alpha-1,6-bonds. In addition, 5 of these strains were able to hydrolyze mannans whose mannose residues were bound by alpha-1,3-bond, and 2 strains could synthetize mannanase active towards yeast beta-mannane with 1,3 and 1,4 bonds. The strains tested showed a very low, if any, lytic activity towards yeast Saccharomyces and Candida. This gives evidence that mannanase is an enzyme unable to perform independently lysis of the yeast cell wall.

Actinomyces↗
PubMed1980

[Allomonas--a new group of microorganisms of the Vibrionaceae family. I. Research methods and preliminary results of differention from aeromonads and vibrios].

The comparative study of 95 strains of Aeromonas, Plesiomonas and various Vibrio species by 49 characteristics (disregarding those common to all representatives of the Vibrionaceae family) allowed to distinguish a separate group of microorganisms differing from Aeromonas by 17 characteristics, from Plesiomonas by 13 characteristics and from Vibrio by 7 characteristics. The new microogranism was provisionally named Allomonas. The taxonomic study of the new microorganism continues.

Aeromonas↗
PubMedDate not supplied

[Effect of bicarbonate level rise on utilization of nonprotein nitrogen 15N by the rumen microorganisms].

The intensity of 15N uptake from labelled urea by a mixed population of the rumen contents microorganisms was studied as affected by various HCO3- levels. Practically there exist a relation between a pronounced positive effect of sodium bicarbonate on the efficiency of urea nitrogen utilization by the rumen fluid microorganisms and the protein synthesis which suggests their combined application to be advisable. However, significance of the differences is not high, first of all due to a great viriation of data for certain animals.

Animals↗
PubMedDate not supplied

[Resistance of microorganisms of upper layers of the atmosphere to ultraviolet radiation and a high vacuum].

Solar radiation and high vacuum are the main factors affecting the incidence of microorganisms in the stratosphere and mesophere. It has been established in experiments that the conidia of Aspergillus niger are most resistant of UV irradiation. The conidia of Penicillium, the spores of Papulaspora anomala and Circinella muscae, and the vegetative cells of Micrococcus and Mycobacterium are more susceptible to UV radiation. All of the isolated microorganisms have been shown to be resistant to high vacuum. Their inactivation varied within the range of 2 to 16%, with an exception of Micrococcus cells (40%).

Air Microbiology↗
PubMedDate not supplied

[Studies of oral microbiocenosis. III. Incidence of microorganisms of the Mycoplasma genus].

Microorganisms of the Mycoplasma genus were found in the washing fluids of the oral cavity in 2% of healthy youths, and in 57.1% of patients with parodontal lesions: 25.7% in the buccal fluid, 17.1% in the dental tartar and 34.2% in the gingiva exsudate. Microplasma was not found in dental caries and in the radicular canals with pulpar gangrene. Although these microorganisms were frequently found in subjects with parodontal lesions they cannot be implicated with certainty in their aetiology.

Humans↗
PubMedDate not supplied

[Interrelationship between populations of cellulolytic microorganisms during digestion of cellular tissue by rumen contents].

Digestion of blotting paper and straw by microorganism contained in the rumen of cattle was studied. It was established that bacterial populations (with inhibition of fungi by nystatin) and fungal populations (with inhibition of bacterial by penicillin and streptomycin) digested a greater amount of cellular tissue than the native rumen contents did. Counting the bacterial and fungal populations suggested the existence of competitive relationships between the cellulolytic microorganisms of the rumen.

Animals↗
PubMed1976

Demonstration of microorganisms in tissues by the ABT and KOH-ABT topo-optical reactions.

The aldehyde-bisulphite-toluidine blue (ABT) reaction, as a selective topo-optical test of vicinal OH and amino-OH groups is suited for the selective demonstration in tissues of microorganisms of polysaccharide containing cells. Alkaline pretreatment of the polysaccharide cell walls, releases, by splitting the O-acyl radicals, further vicinal OH groups for the ABT reaction, thus actually increases the sensitivity of the method. The topo-optical reactions are characterized by a strong birefringence induced by oriented dye-binding, due to the linear arrangement of polysaccharides composing the cell wall. Differences in the character of birefringence have made it possible to work out a new method for the analysis of the cell wall ultrastructure as well as to demonstrate microorganisms in tissues. The practical value of the reactions is illustrated by examples.

Aldehydes↗
PubMedDate not supplied

The role of antibiotics in the evolution of microorganisms.

Bacteria were the first living beings to appear on our planet: the most ancient fossils available, all of them were procaryotic microorganisms, developed 4, 5 billion years ago. The paleomicrobiological studies made on that kind of fossils, which are by now several hundreds in each continent, proved bacteria to have constantly evolved and to have originated the modern Eubacteria as well as the Archebacteria and the Cianobacteria. These last appeared about 2 billion years ago and, having acquired the oxygen-type photosynthesis, have caused the formation of a large amount of organic material, afterwards used by the younger organisms, and have modified the atmosphere introducing oxygen in it and conditioning in this way the other living being's evolution. From Bacteriaceae and Cyanobacteria derive the eucaryotic microorganisms (algae, fungi, protozoa, mould) and, little by little, all the other organisms both vegetable and animal subjected to the evolutionary pressures. Nevertheless bacteria undergo more frequently than all the others the evolution law because of their short reproductive time; this is the reason why bacteria are favourite compared with the other organisms. In fact each species is subjected to a genetic mutation every 10(5)/10(6) generations: in the vegetables and animals the consequences of a genetic mutation will be evident after millennia whereas in the bacteria the mutation happens in a short time. We ourselves have witnessed the revolution which took place in the bacteria populations during the last half century when numerous antibiotic-resistant strains appeared.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗
PubMed1995

[Instrumental technics for the detection of microorganisms in brewing].

Although modern production techniques keep microorganism levels very low in both finished beer and in beer process, there is still concern about early detection and prevention of accidental proliferation of brewery spoilage microorganisms. Traditional microbiological techniques can detect such low levels, but no results are obtained before 3 to 6 days of incubation. That is why rapid or even "instant" techniques are a main objective of research in the brewing industry. In this work, some instrumental techniques (DEFT, MMCF, impedance, pH, immunology and PCR based techniques, bioluminometry) are described and considered from the point of view of their regular use in brewery Microbiological Quality Assurance Laboratories. Real case experiences are brought forward.

Bacteriological Techniques↗
PubMed1995

Microorganisms isolated from the corneal surface before and during topical cyclosporine treatment in dogs with keratoconjunctivitis sicca.

The effect that topical administration of cyclosporine would have on the number and type of microorganisms isolated from the corneal surface of dogs with keratoconjunctivitis sicca was studied. Schirmer tear test wear performed on and corneal swab specimens were collected from 61 eyes of 31 dogs with keratoconjunctivitis sicca prior to and after 3, 6, and 12 months of treatment with cyclosporine. In eyes that responded to cyclosporine treatment (Schirmer tear test value increased by > or = 5 mm/min, compared with pretreatment value), the percentage of eyes from which bacteria were isolated 3, 6, and 12 months of treatment was significantly (P < 0.001) less than the percentage from which bacteria were isolated prior to treatment. However, among eyes that did not respond to treatment, we did not detect a significant change over time in prevalence of bacteria or type of bacteria isolated. The percentage of eyes from which fungi were isolated decreased during treatment; however, the small number of eyes in which fungal culture results were initially positive precluded demonstration of a significant differences over time in the frequency with which specific bacterial genera were isolated, with the exception of beta-hemolytic Streptococcus spp. Opportunistic corneal infections were not detected even though none of the dogs received antibiotics. An increase in production of tears, which contain anti-infection, proteins, was believed to be the primary factor responsible for the decrease in the percentage of eyes from which microorganisms could be isolated.

Animals↗
PubMedDate not supplied

[Technics for isolation of ATP from microorganisms].

A technique for isolation of ATP from microorganisms is suggested. The technique is based on increasing permeability of the cell membrane for substances of low molecular weight during dehydration. Treatment of the dry biomass with boiling water gives a higher yield of ATP from the cells of eukaryote and prokaryote microorganisms as compared with other techniques, and permits to register the amount of APT at the moment of experiment.

Adenosine Triphosphate↗
PubMedDate not supplied

[Hydrophobic characteristics of the microorganism cell surface].

Hydrophobic properties of the surface of microorganism cells can be featured by parameters that define the equilibrium of cellular adsorption on liquid carbohydrates: constant of sorption equilibrium, a maximal number of adsorbable cells, as well as coefficient of cellular distribution (Kd) between liquid and organic phases that can be determined either with the equation of adsorption isotherm or experimentally. It is shown that the latter technique gives a more informative characteristics of the hydrophobicity levels in the surface of cells than the percentage of of hydrophobicity cited in literature. The results of this study can be used in the screening of microorganism strains and in the solvation of problems of industrial microbiology related to the fixation of cells on differently structured carriers.

Bacteria↗
PubMedDate not supplied

[Application of the method of capillary microscopy to determing the total population and biomass of microorganisms in seas and oceans].

The total number and biomass of microorganisms in samples of sea water were determined by direct counting in capillaries by Perfiliev and Gabe after preliminary concentration of water by filtering it through membrane filters. Reliability of the figures obtained upon concentration of diluted bacterial suspensions (10(3) to 10(5) cells/ml) was checked with dilutions of the cell suspension of Bacterium parvulum. The total number of the microorganisms was determined in 22 samples of sea water fixed with 4 to 5 per cent formalin, and deviations for each capillary were calculated.

Bacteriological Techniques↗
PubMed1995

Population genetics and strain typing of microorganisms: how to detect departures from panmixia without individualizing alleles and loci.

The actual impact of genetic exchange in natural populations of microorganisms is presently under debate. It is indispensable to precisely estimate this parameter in order to assess the stability in space and time of these microorganisms' genotypes, and hence, their epidemiological and medical relevance. Population genetic concepts make it possible to address this question rigorously. Nevertheless, the analyses are made difficult by the fact that very often, the genetic markers used do not allow discrimination of individual alleles and loci. This work presents some linkage disequilibrium tests usable even under these conditions, and hence applicable with any class of marker (isoenzymes, RFLP, RAPD, DNA fingerprinting).

Bacterial Typing Techniques↗
PubMed1994

Establishment of the microorganism growth model at an inhibitory condition by microcalorimetric method.

The growth thermograms of Staphylococcus albus and Staphylococcus aureus were determined by using the 2277 thermal activity monitor, using a microorganism growth model with inhibitory conditions, the specific growth rate and the thermogram curves at different temperature and acidities were determined. From these curves, the microorganism optimum growth temperature and acidity were defined.

Calorimetry↗