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PubMedDate not supplied

[Evaluation of a colorimetric method for studying the interaction between microorganisms and intestinal epithelial cells].

The aim of the present study was to gain further insight on the reliability of the colorimetric determination of the activity of bacterial nitrate reductase to evaluate bacterial concentrations and interaction between microorganisms and enterocyte-like cells. Nitrite produced after incubation of the samples with a nitrate-formate solution was determined with a diazotization reaction with sulphanilic acid and N-naphthyl-ethylene-diamonium dichloride. Cell association assays were performed with differentiated Caco-2 cells. A biphasic relationship was found between nitrite concentration and bacterial densities. This behavior seems to be due to the sigmoideal character of the kinetics of nitrate reduction. Association to Caco-2 cells was strongly strain dependent being Staphylococcus aureus ATCC 25923 the strain showing the highest values of association. For some strains, percentages of association calculated on the basis of the colorimetric assay were significantly higher than those calculated in terms of viable counts. Bacterial association with enterocyte-like cells can be evaluated by measures of the activity of bacterial nitrate reductase provided that the biphasic relationship between bacterial and nitrite concentrations is taken into account for the calculations. Results presented in this paper show the applicability of the colorimetric method to assess the amount of microorganisms associated to human enterocytes in culture.

Bacillus cereus↗
PubMedDate not supplied

[Microorganism "Montezuma" of the order Rickettsiales: the potential causative agent of tick-borne disease in the Far East of Russia].

A new microorganism, tentatively named "Montezuma" was detected in ticks and in specimens (blood, bioptic specimens of the primary affect) taken from patients with an acute fever disease, etiologically linked with the bites of Ixodes ticks in the Far East of the Russian Federation. After sequencing the products of the amplification of DNA isolated from ticks with wide-spectrum primers new primers were developed, highly specific to the unusual sequence thus obtained. The study revealed that ticks of the species Ixodes persulcatus (97%) and Haemophysalis concinnae (5%) contained DNA of this microorganism. The same DNA was detected in materials taken from the patients. The phylogenetic analysis of the gene showed that this organism formed an independent and well defined branch within the order Rickettsiales. The nearest homology (89%) was observed with recently detected endosymbiotes Acanthamoeba. The similarity with their relatives from the families Rickettsiaceae and Anaplasmataceae of the order Rickettsiales was within 81-86%, which made it possible to infer the existence of, probably, only a new genus, but also a family. The isolated DNA belonged, supposedly, to the new microoganism which caused a tick-borne disease in humans, transmitted through bites of Ixodes ticks, and was, supposedly, widely spread in the southern area of the Khabarovsk Territory.

Acute Disease↗
PubMedDate not supplied

[A plate method to screen for microorganisms producing xylose isomerase].

A plate method was developed to screen for xylose isomerase-producing microorganisms based on the use of 2,3,5-triphenyltetrazolium as an indicator of D-xylulose, the D-xylose isomerization product. The use of this method allows microorganisms to be differentiated by the character of the enzyme synthesis (inducible or constitutive).

Aldose-Ketose Isomerases↗
PubMedDate not supplied

[Mathematic modeling of the dynamics of the interacting population of the rhizosphere microorganisms].

A quantitative model is proposed to describe the population dynamics of associative nitrogen-fixing microorganisms in the plant rhizosphere as dependent on the rate of carbon substrate exudation by plant roots. By changing the values of the basic model parameters, the effect of various factors on the behavior of two competing populations of rhizospheric microorganism can be studied.

Bacteria↗
PubMed2004

Saprophytic microorganisms in food - impact on human health.

The paper discusses issues that research, in both the world and the Czech Republic, has for the most part been resolved. Yet in practice very little attention has been paid to them in this country. And yet non-specific microbial toxicoses produced by the enzymatic activity of various microorganisms in certain substrates, more specifically in food, may cause not only fairly insignificant, but also highly significant threats to human health, in both individuals and large groups of the population. They are thus important not only from a microbiological, but also epidemiological point of view. In this respect the greatest danger represent microbes with a lipolytic or proteolytic activity. Aldehydes, ketones, peroxides, epoxides and various other polymeres may be generated in fats, more particularly in butter, and in foodstuffs containing small or large proportion of fats, while various forms of biogenic amines may be found in foodstuffs containing proteins. The result are non-specific toxicoses - epidemiological examinations clearly point to an alimentary toxicosis, yet bacterial toxins cannot be demonstrated and possible products of enzymatic microbial activity are disregarded. In all such instances we should not only explore the suspicious foodstuffs for the presence of pathogenic or conditionally pathogenic microbes and bacterial toxins, but we should also carry out qualitative and quantitative investigations to detect lipolytic or proteolytic microorganisms (depending on the content of the foodstuff) and their metabolic activity.

Bacterial Toxins↗
PubMed2004

[Interaction between chlopyrifos and microorganisms in soils].

The experimental results showed that in sterilized soils, the degradation rate of 50 mg x kg(-1), 500 mg x kg(-1) and 5,000 g x kg(-1) chlopyrifos was very slow (only 20% after 60 d), and in soils which previously treated with chlopyrifos, the degradation rate of 50 mg x kg(-1), 500 mg x kg(-1) and 5,000 mg x kg(-1) chlopyrifos was 100%, 90% and 80%, respectively. However, in un-sterilized and untreated soils, the degradation rate was at the medium of the rates mentioned-above, indicating that soil microorganisms played an important role in chlopyrifos degradation, and using chlopyrifos could induce the chlopyrifos degrading ability of soil microorganisms. Compared to the soils untreated with chlopyrifos, the soils treated with 50 mg x kg(-1) and 500 mg x kg(-1) chlopyrifos had somewhat increased bacteria and fungi during a short period of treatment, which recovered to normal level after 60 days. But, when treated with 5,000 mg x kg(-1) chlopyrifos, the bacteria and fungi were inhibited, and couldn't recover after 60 days. Under the same treatment condition, the number of bacteria and fungi was not different between soils previously treated and untreated with chlopyrifos, which indicated that enhanced degradation of chlopyrifos was not decided by the numbers of bacteria and fungi, but by their ability of enhanced degradation.

Bacteria↗
PubMed2004

[Pilot test on oil field wastewater biotreatment with thermophilic microorganisms].

The thermophilic microorganisms (50-60 degrees C) are introduced and the contact oxidation technology is adopted to treat with the high temperature effluents from an oil field in this paper, which solves a problem that the effluents need to be cooled in routine biotreatment. The results of the pilot test show that the HRT of the biotreatment system adjusted to 8-18h can make CODCr of the effluents stable at 175-263mg/L and oil content under 10mg/L on condition that the temperature of the influents keeps at 60-65 degrees C, CODCr 300-590mg/L and the quality of the oil wastewater is greatly fluctuant. Flocculating process, then, can effectively flocculate and precipitate the suspending and residual chroma pollutant from the effluents of biotreatment and CODCr in the effluents of flocculating process can reduce to 136-229mg/L. And CODCr even reduces to under 150mg/L after flowing by sand and activated carbon filtration equipments. Under the high temperature condition, furthermore, combined stuffing is an ideal carrier for the thermophilic microorganisms.

Bacteria, Aerobic↗
PubMed2004

[Three Bombyx mori genes, chi, gluE and fruA, encode proteins homologous to microorganism and primary analysis of horizontal gene transfer].

According to the analysis of large scale EST sequencing of silkworm, Bombyx mori, we found that chi, glue and fruA of silkworm have very high homology at amino acid level and closely phylogenetic relative with that of microorganism, but lower similarity with genes of eelworm (Caenorhabditis elegans), fruitfly (Drosophila melanogaster), mosquito (Anopheles gambiae) and other relative insects, respectively. It indicates that each of them is likely to have common ancestor with that of microorganism. Namely, microbial genes were likely transferred to silkworm by horizontal gene transfer, instead of the vertical inheritance in evolutionary manner.

Animals↗
PubMed2004

[Determination of sensitivity of biofilm-positive forms of microorganisms to antibiotics].

Nosocomial infections caused by biofilm-positive microorganisms are a serious therapeutic problem. In the biofilm, microorganisms are protected against adverse effects of the external environment, including the action of antibiotics. It is well known that the values of minimum inhibitory concentrations (MIC) determined for planktonic forms do not correspond to the actual concentrations of antibiotics necessary for the eradication of bacteria in a biofilm. The purpose of the study was to propose a method of determining minimum biofilm inhibitory concentrations (MBIC) and minimum biofilm eradication concentrations (MBEC) and to compare these values with MIC values. Biofilm-positive strains of Staphylococcus epidermidis were cultured so as to form a biofilm layer on polystyrene pegs. The biofilm on the pegs was then exposed to the action of antibiotics and after 18 hours we determined the minimum biofilm inhibitory concentration (MBIC). The evaluation of minimum biofilm eradication concentrations was done colorimetrically from the metabolic activity of surviving cells. MBIC and MBEC values were many times higher than MIC values. We selected such a duration of the biofilms cultivation on the pegs of the plate, which ensured that the number of bacterial cells corresponded to standard MIC assessment. The MBEC values established in our study indicate that the currently used concentrations of tested antibiotics cannot be used in monotherapy for an efficacious eradication of a biofilm. The MBEC determination is a far more laborious and time-consuming method than the determination of MIC, but the use of plates with pegs facilitates the handling of biofilms. The advantage of our method is the possibility of standardization of the size of the inoculum and thus of the whole MBEC assessment.

Biofilms↗
PubMed2004

[Experimental evaluation of possible transmission of human alpha-2 interferon artificial gene to the other microorganism species].

Described within the case study are experimental evaluation data on the remote results of introduction of gene-engineered microorganisms (GEM) of the B-7092 B. subtilis strain into the environment with the follow-up ranging from 1 to 7 years. No bacteria of the above GEM were detected (among selected 19 bacterial cultures) in soil samples from an agricultural farm, where the VETOM 1.1 probiotic was used for the treatment and prevention of cattle; primary and precise identification (two-round PCR with specific primers) was applied. The introduction of the B-7092 B. subtilis strain into the environment did not result in its unlimited growth and proliferation in soil. No transfer of plasmid genes (genes of leukocytic human alpha-2 interferon) from the B-7092 B. subtilis strain GEM to microorganism species available in the environment (soil) was registered. No recombinant plasmid DNA from lysed GEM cells was detected in soil samples.

Agriculture↗
PubMed2004

The effectiveness of a multi-spark electric discharge system in the destruction of microorganisms in domestic and industrial wastewaters.

The aim of this work was to investigate the effectiveness of a high voltage multi-spark electric discharge, with pulse energy of 1 Joule, in killing microorganisms in wastewater. Wastewater from primary treated effluent arising from domestic and industrial sources was abstracted for continuous pulsed discharge disinfection. The wastewater contained a large mixed population of microorganisms (approximately 10(7) CFU ml(-1) [10(9) CFU 100 ml(-1)] total aerobic heterotrophic bacteria) including vegetative cells and spores. The electrical conductivity of the wastewater ranged from 900-1400 microS cm(-1) and it was shown that a specific energy of 1.25-1.5 J cm(-3) was required to achieve 1 log reduction in bacterial (faecal coliforms/total aerobic heterotrophs) content. This is higher than that previously shown to reduce the population of E. coli in tap water of low conductivity, demonstrating the role of total wastewater constituents, including dissolved and particulate substances, water colour and the presence of microbial spores, in effective disinfection. The system can be engineered to eradicate microbial populations to levels governed by legislation by increasing treatment time or energy input.

Bacteria↗
PubMedDate not supplied

[Utilization of the mix of growth and nongrowth substrates by microorganisms].

Author's experimental data and those from literature, concerning the utilization of growth and nongrowth substrates by microorganisms, are presented in the review. The notions "growth" and "nongrowth" substrate as well as the types of transformation of mixed substrates (mixotrophy, diauxia, nongrowth oxidation, cometabolism, syntabolism) have been considered. Main propositions of the conception of auxiliary substrate and the essence of energetic classification of substrates have been presented. Data from literature concerning the effect of cultivation conditions (concentration of substrates, their ratio, cultivation method, dissolution rate under continuous cultivation, etc.) on the character of substrate mixed use, as well as the use of mixed substrates aimed at the intensification of microorganism growth. Data are presented on the intensification of metabolites synthesis (e. g. microbial exopolysaccharide etapolan) on the mixture of energetically non-equivalent growth substrates.

Bacteria↗
PubMedDate not supplied

Antimicrobial susceptibility of air-dispersed microorganisms in dental settings.

To determine the number and the susceptibility of microorganisms collected in a clinical environment against the antimicrobial agents used commonly in dentistry, petri dishes containing trypticase soy agar were exposed to air in different sites of a multi-chair dental clinic before, during, and after multiple clinical procedures and incubated for 24 hours under aerobic conditions. Colonies were identified by Gram stain technique and biochemical tests. Commercial paper disks containing widely prescribed antimicrobial agents (beta-lactams, macrolides, and clindamycin) were used to perform the antimicrobial susceptibility tests. The groups (colony forming units = cfu/m2/min) were submitted to the Kruskal-Wallis test (alpha = 5.0%), considering different clinical situations and environmental sites. During clinical procedures, the number of microorganisms increased (p < 0.05). This study highlights the need for established strategies to prevent resistant bacterial strains from emerging in dental settings.

Air Microbiology↗
PubMedDate not supplied

[Evaluation of a semisolid medium for preserving microorganisms of the Enterobacteriaceae family].

26 bacterial strains from the Enterobacteriaceae family were studied to evaluate the maintenance of the cultural. tinctorial and biochemical properties of the microorganisms originally preserved in the semisolid medium of conservation since the end of the 1980's. 22 of them were viable, showing their survival for more than 10 years. The microorganisms have been maintained in this medium since their introduction into the Laboratory of Collection of Microbial Cultures of the National Institue of Hygiene. Epidemiology and Microbiology of Cuba. They have been used as pattern strains in the internal control of the quality, of reagents and culture media produced in this center for their further use in the microbiological evaluation of environmental samples This medium gives good results for the conservartion of strains of Enterobaceriaceae and may be used in laboratories with scarce resources.

Culture Media↗
PubMedDate not supplied

Microorganisms and parasites in chronic infective diarrhea.

AIM: To reveal the pattern of microorganisms in chronic infective diarrhea cases. METHODS: We examined all patients suffering from chronic infective diarrhea over a six year period The patients were examined physically and at the same time laboratory tests,colon enema X-ray and colonoscopy, ileoscopy, upper GI endoscopy and small bowel X-ray were performed. RESULTS: We found 138 (66. 7%) chronic infective diarrhea from 207 chronic diarrhea patients. Parasitic causes were Candida albicans (48.55%), Blastocystis hominis (6.52%), Entamoeba histolytica (3.62%), and Giardia lamblia (3.62%) etc. Bacterial causes were Pathogenic E. coli(34.78%), Aerobacter aerogenes (3.62%), Mycobacterium tuberculosis (3.62%), Geotrichum (1.45%), Shigella sonnei(0. 72%), Salmonella paratyphi (2.89%)etc. CONCLUSION: The most frequent microorganisms and parasites found in chronic infective diarrhea were pathogenic E.coli and Candida albicans.

Adult↗
PubMedDate not supplied

[Database on natural and transgenic luminous microorganisms: "BiolumBase"].

The database "BiolumBase" is designed for the selection and systematization of available world information on microorganisms containing bioluminescent systems; it includes two sections: "natural" and "transgenic" luminous microorganisms. At present, logic schemes of divisions, classification of the objects, presentation of characteristics, and the inputs of relative information, as well as the necessary program modules including links to the database, are developed. The database is constructed on the basis of published data and our own experimental results; the subsequent linkage of the database to the Internet is envisaged. Users will be able to obtain not only the catalogues of strains but also information concerning the properties and functions of the known species of luminous bacteria, the structure, regulatory mechanisms, and application of bioluminescent systems and genetically engineered constructions with lux genes, as well as to find references and to search strains by using any set of attributes. The database will provide information that is of interest for the development of microbial ecology and biotechnology, in particular, for the prediction of biological hazard from the application of transgenic strains.

Bacteria↗
PubMed2004

Studies on the amino acid fermentation. Part 1. Production of L-glutamic acid by various microorganisms.

Screening tests for glutamate producing strains were carried out, with the media containing carbohydrate and ammonia source as chief ingredients. Glutamate as well as certain other amino acids was detected by paper chromatography in culture broth of many microorganisms tested. Accumulation of L-glutamate in a significant amount (at least a few mg of glutamate per ml of broth) has been demonstrated by various strains of bacteria, streptomycetes, yeasts, and fungi. The highest level of glutamate production has been obtained by a new species of Micrococcus, yielding as much as 0.25 mole of it from one mole of glucose. The courses of fermentations mainly by known strains of microorganisms are shown. The importance of the cultural condition and strain specificity for the production of amino acids are briefly described.

Amino Acids↗
PubMed2004

[An important mission for microbiologists in the new century-cultivation of the unculturable microorganisms].

The present review summarizes the recent advances in cultivating the so-called recalcitrant microorganisms in various natural environments. Firstly, the use of new electron donors and acceptors reveals a list of unique and previously unrecognized physiotypes (Table 1), and the growth supporting reactions include oxidation of phosphite, arsenite, soil humic substances, benzene, Fe (II) and aryl-halides. The novel pure cultures obtained include: Desulfatogenum phosphitoxidans, lithochemotrophic arsenite oxidizing bacteria, Dechloromonas agitata, Dechalosoma suillum, and various Proteobacteria capable of decomposing soil humic substances anaerobically. Secondly, the adaption of nutrient-poor media (down to 1/100 of the traditional concentration), including sea water, soil extract and extension of natural habitats (insect hind-gut, submarine hot vent) are extremely rewarding. For example, cultivation of the ubiquitous SAR11 marine bacterioplankton clade reveals a phylum, small in cell size and genome, but dominating in ocean surface, thus constituting a huge biomass on earth. In addition, the nanosized hyperthermophilic Archaeon from a submarine hot vent, represents an unknown phylum, and because of its symbiotic living with Ignicocous cells, it is named Nanoarchaeum equitans. Its genome size is only 500kb, the smallest for prokaryote. Considering its hyperthermic living environment and small genome, N. equitans may possibly still a primitive form of microbial life and affords an advantageous culture for the study of life origin and evolution on earth. Thirdly, several novel isolation techniques have been developed such as gel microdrop encapsulation and diffusion chamber, both with the advantages of high-throughout operation and simulating to certain extent of the natural environment, thus allowing growth synergy based on cross-feeding to occur. Finally, it should be noted that the cultivation of unculturable microorganisms mentioned in this review does not require expensive and sophisticated equipments and most of the techniques can be adapted in our laboratory at home.

Bacteria↗