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At least 1,225 records · Page 68Linked to original sources
PubMedDate not supplied

[Effect of the exogenous lipids of complex media on the fatty acid composition of mycelial microorganisms].

The effect of exogenous lipid sources on the composition of fatty acids was studied in actinomycetes of the Streptomyces genus and in fungi belonging to the genera Blakeslea, Cunninghamella and Penicillium. The following sources of exogenous lipids were used: soybean and maize flour, sunflower by-products, chicken droppings, maize extract, yeast extract, peptone, sperm whale fat, sunflower and palm oil. The composition of fatty acids in total extracted lipids of the studied mycelial microorganisms was shown to reflect two processes: lipid synthesis de novo and assimilation of exogenous fatty acids. This fact ought to be taken into account both in the chemotaxonomic interpretation of fatty acid composition and in practical recommendations for the utilization of microbial lipids. It is of particular interest to study the physiological role of exogenous lipid metabolism in the cells of microorganisms.

Chromatography, Gas↗
PubMed1987

[Advances in gene engineering of microorganisms].

A novel branch of national economy--biotechnology is being developed, based on genetic engineering. The construction of strains using the methods of molecular cloning has led to-date to creation of new biotechnological processes. Further advance in biotechnology would be mainly promoted by the possibilities of application of gene engineering to reorganization of industrially important microorganisms. These are bacilli employed for production of vitamins, enzymes, insecticides; streptomycetes--the producers of antibiotics; yeasts applied in bakery industry, in production of fodder proteins; pseudomonads which will be helpful in development of effective biological means for protection of environment, etc. So, vector molecules based on plasmids and phages have been constructed for best-studied representatives of industrial microorganisms, the methods of introduction into the cell of hybrid DNA molecules worked out, the problems of optimization of foreign gene expression being currently solved.

Bacteria↗
PubMedDate not supplied

[Survival of microorganisms frozen on solid medium (author's transl)].

Different freezing methods have been studied for 12 microorganisms. This study has been carried out on solid support in the conditions near the freezing of foods. The survival rates are on relation with species and freezing methods. The survival of some microorganisms during a storage at -20 degrees C has been studied.

Bacterial Physiological Phenomena↗
PubMed1977

Application of gas chromatography to diagnosis of microorganisms and infectious diseases.

Gas chromatography (GC) can be used to characterize microorganisms chemically. Microbial whole cells and cell extracts can be analysed by GC after being thermally or chemically degraded, i.e. pyrolysed or hydrolysed. Microbial metabolic products can be detected by GC analysis of culture media or the atmosphere above such media, i.e. headspace analysis. Pyrolysis products can be analysed direct, while hydrolysis products and non-volatile metabolites must be derivatized before being chromatographed. Differences in the chromatographic patterns can be used to differentiate between microorganisms. Detection of metabolic products in body fluids by means of GC constitutes a potential technique for the rapid diagnosis of infectious diseases.

Chromatography, Gas↗
PubMedDate not supplied

[Studies on enzyme preparation from microorganisms in the USSR].

The paper describes the most important investigations aimed at the preparation and examination of enzymes from microorganisms which have been recently carried out in the USSR. It discusses selected theoretical studies of the regulation of the enzyme synthesis by microorganisms. The paper presents data on the properties of certain enzymes which are of practical importance for different branches of people's economy and public health.

Bacteria↗
PubMed1978

Enumeration of petroleum-degrading marine and estuarine microorganisms by the most probable number method.

Several media designed for use in a most probable number (MPN) determination of petroleum-degrading microorganisms were compared. The best results, i.e., largest numbers, were obtained using a buffered (32 mM PO4=) liquid medium containing 1% hydrocarbon substrate. Of 104 presumptive oil degraders tested, 20 grew on oil agar medium but did not utilize oil or a mixture of pure paraffinic hydrocarbons (C10 to C16 n-alkanes) in liquid (MPN) medium. Visible turbidity in the liquid medium was correlated with hydrocarbon utilization. Counts of petroleum degraders obtained using liquid medium (MPN) were in most cases higher than those obtained on an oil-amended silica gel medium. Both procedures yield an estimation of oil degraders, and the oil-amended agar permits growth of organisms which do not degrade crude oil. All strains of oil-degrading microorganisms examined in this study were lipolytic, but the converse was not always true.

Alkanes↗
PubMed1986

Genetically-engineered microorganisms: I. Identification, classification, and strain history.

We have argued that accurate identification of the microorganism will form a cornerstone of the assessment of potential hazard. Appropriate methodology for identification exists, and is continually under development and refinement. Organizations such as the American Type Culture Collection will perform certified identifications for relatively low cost. Thus there appears to be little reason that an organism should not be identified insofar as current microbiology allows prior to submission for PMN review. We suggest that a complete microbiological characterization be considered an essential element of an acceptable PMN. To accomplish this, however, current institutional arrangements for the protection of trade secret information needed in the process of identification may need to be improved. An accurate identification of the strain will often provide access to important information with which to evaluate its ecology, pathogenicity, biochemistry, and genetics. Specialized texts, the scientific literature, and professional consultation are ready sources of such information. However, a major effort should be made to establish a data base that can specifically address the needs of biohazard evaluation. This could be done, in part, by collecting information about the construction, and about the behavior in the environment of genetically-engineered microorganisms that are now under development and will soon be tested or used. Identification information may also eventually be useful for the formulation of hypotheses about possible modes of harm or about relative safety, based on phylogenetic relationships. This is a very difficult undertaking at present, however. Microbial taxonomy is currently in a process of radical reevaluation as new macromolecular sequence information reveals previously unsuspected phylogenetic relationships, and disturbs categorizations based on older types of traits such as morphology, etc. This means that both inferences about relative safety and about possible modes of harm from taxonomic relationships must be highly tentative based on current information. Regulatory authorities may wish to consider requesting confirmatory DNA hybridization data or other macromolecular sequence comparisons in cases where strong arguments related to safety must be made from taxonomic information in relatively poorly studied groups of organisms. Detailed strain histories would provide valuable information for safety evaluations.(ABSTRACT TRUNCATED AT 400 WORDS)

Bacteria↗
PubMed1986

Bactericidal effects induced by laser irradiation and haematoporphyrin against gram-positive and gram-negative microorganisms.

Laser irradiation of tissues treated in vivo with haematoporphyrin (Hpr) is known to result in a cytocidal effect, reportedly more pronounced in tumour tissues. To ascertain whether this cytocidal phenomenon can occur not only in eukaryotic but also in prokaryotic cells, the authors devised a model system in vitro consisting of bacterial cultures in liquid and in solid media. Bacteria photosensitized with Hpr were subsequently exposed to laser beams and to daylight; then normal microbiological techniques were used to determine whether any bactericidal effect occurred. Satisfactory results were achieved, particularly against Gram-positive microorganisms; a partial inhibition of Gram-negative microorganisms was also observed.

Culture Media↗
PubMedDate not supplied

[Immobilization of microorganisms on latex for producing artificial flocs].

Microorganisms belonging to the genera Pseudomonas, Micrococcus, Bacillus and Rhodotorula are flocculated with divinyl styrene latex. The process of flocculation depends on a number of physico-chemical factors but, all in all, is universal for microorganisms with different taxonomy, morphology and physiology. The structure of artificial bioflocs has been studied using optical and scanning electron microscopy.

Bacteria↗
PubMed1986

Alveolar phospholipids of 17-day-old pigs exposed to microorganisms of nonpulmonic origin.

Alveolar lining material was obtained from gnotobiotic pigs; gnotobiotic pigs exposed to aerobes, anaerobes, or mixtures of both microorganisms; and conventional farm-raised pigs. Alveolar lining material concentrations of phosphatidylcholine, sphingomyelin, phosphatidylserine, phosphatidylinositol, phosphatidylethanolamine, phosphatidylglycerol, and lysolecithin were determined. Seventy-four pigs were allotted to the following groups: 1--gnotobiotes (n = 13), 2--gnotobiotes with aerobes (n = 6), 3--gnotobiotes with anaerobes (n = 31), 4--gnotobiotes with anaerobes and aerobes (n = 2), 5--gnotobiotes with facultative anaerobes (n = 9), and 6--conventionally farm-farrowed (n = 13). The conventionally raised pigs had lysolecithin, sphingomyelin, and phosphatidylinositol concentrations that were significantly different from those of all other groups of pigs. Phosphatidylethanolamine was significantly decreased in group 6 pigs when compared with that in all other groups. There were also statistically significant differences between the gnotobiotic (group 1) and the exposed gnotobiotic (groups 2, 3, 4, 5) pigs, although the differences were less pronounced. Since intestinal microbes produce alveolar lining material phospholipid differences, studies need to be concerned with phospholipid changes that occur after exposure to lung-specific microorganisms and with physiologic changes in lung function associated with the phospholipid changes.

Animals↗
PubMed1987

Clinical limitations of in vitro testing of microorganism susceptibility.

General concepts in evaluating the clinical importance of discrepancies between in vitro susceptibility tests of microorganisms and in vivo results are reviewed, and four problematic antibacterial-bacterial combinations are discussed. The three most common in vitro testing systems--agar disk diffusion, agar dilution, and broth dilution--are designed to detect the minimum inhibitory concentration (MIC) of an antimicrobial agent. However, agar and broth systems cannot include all of the biologic variables found within the human body. Factors affecting the reliability of in vitro testing systems include the limitations in interpreting MIC data, because in vitro test conditions cannot duplicate the host environment; the variability of testing media (e.g., acidic versus alkaline, differences in cation content); and the limiting effect of protein binding on an antimicrobial agent. In vitro testing systems do not consider the pharmacokinetics of the antimicrobial agent or the postantibiotic effect, whereby microbial growth is suppressed even when the antibiotic concentration falls below the MIC. The variability in drug distribution to infection sites within the body is also not considered. The following antimicrobial agent-bacterial combinations present specific problems to the clinician: trimethoprim-sulfamethoxazole and Group D enterococcus, cephalosporins and methicillin-resistant Staphylococcus aureus, aminoglycosides and Staph. aureus, and aminoglycosides and Pseudomonas aeruginosa. Despite the limitations of currently available systems, in vitro testing of the susceptibility of microorganisms can be an invaluable tool in selecting antimicrobial therapy when it is used in conjunction with data regarding the clinical course of the infected patient.

Aminoglycosides↗
PubMedDate not supplied

[The dynamics of the microorganism count of active sludge during the aerobic treatment of sewage].

Dynamics of the active sludge microorganism quantity is studied under different cultivation regimes. It is shown that quantity of microorganisms in different physiological groups depends on the specific growth rate, micro, determined by the dilution rate and biomass recirculation level. The results may be used for selecting optimal regime of the sewage treatment system functioning.

Aerobiosis↗
PubMed1985

[Behavior of microorganisms in wastes from medical practice and household refuse deposited in a model landfill].

Refuse from medical consulting rooms, a mixture of those refuse with municipal refuse (1:10), and municipal refuse were disposed aerobically and roughly anaerobically for over six months in a model landfill. Survival, proliferation, and transportation of microorganisms were estimated at different periods of time. Concentrations of aerobic bacteria and hyphomycetes decreased during the first weeks of deposition but remained later almost unchanged. Concentrations of nonsporeforming indicator bacteria (Escherichia coli, feacal streptococci) decreased more strongly, and E. coli could not be found at latest after 23 weeks. In municipal refuse alone and mixed with refuse from medical consulting rooms, Pseudomonas aeruginosa proliferated temporarily. Leaching of microorganisms from the model landfill was observed in the whole course of the disposal period.

Aerobiosis↗
PubMed1985

[Mineralization activity of microorganisms in refuse from medical consulting rooms and in municipal refuse].

Mineralization activity of microorganisms in refuse from consulting rooms of general practitioners, E.T.N.-specialists, dermatologists, dentists, veterinarians, and in municipal refuse was estimated by means of CO2 and NH3 measurement. In comparison to municipal refuse, the refuse from medical consulting rooms released only low amounts of CO2 and NH3. Only in refuse from the veterinarians consulting rooms relative high mineralization was found, due to specific consistency (fecal contamination) of those refuse. A slight enrichment in pepton of all refuse under test resulted in a strong enhancement of the CO2 and NH3 evolution. That effect indicates either high potential mineralization activity of microorganisms in the refuse from medical consulting rooms and their relative resistance to microbial degradation.

Ammonia↗
PubMed1985

[Cleansing of the skin of metabolic products and microorganisms by the wearing of children's outer clothing made of polyacrylonitrile fibers].

The rate of absorption of metabolite products and accumulation of microorganisms on the skin from knitted wear, with different combination of wool /W/ and polyacrylonitrile fibers /PAN/ and of 100% PAN regular production and modified /11 types of products/, is examined in laboratory and natural conditions, as well as bacteriostatic effect related to some important microorganisms. A clearly expressed reverse dependence is established between the absorbing properties of the knitted wear and the metabolite products on the skin and the progressive increase of synthetic PAN fibres in the content. Especially evident is the difference in the quantity of products between the knitted wear of 100% PAN /regular production and modified/ and 100% wool. Considerable are also the differences in the products with the participation of PAN above 50%. This presuppose bad cleaning ability of these articles and accumulation of residual products. Two vague tendencies--bacteriostatic effect and bad cleaning of skin from the knitted wear with large per cent of PAN fibres /70 and 100%/, which are to be investigated additionally.

Absorption↗
PubMedDate not supplied

Use of tetramethylammonium hydroxide to determine the total fatty acid composition of microorganisms.

A destructive chromatographic method of identifying microorganisms is described. The method is based on hydrolysis of the biomass of the microorganisms in the presence of tetramethylammonium hydroxide, followed by introduction of the hydrolyzate into the heated injector of a gas chromatograph. The main products in this case are methyl esters of fatty acids, the composition of which is used as a diagnostic criterion. Chromatograms of the residues after chloroform-methanol extraction and the dynamics of the change in total fatty acids in the process of growth can also be used for identification. The dynamics of total fatty acids was studied in E. coli strain K-12, and destructive chromatograms for bacteria and yeasts are cited.

Bacteria↗
PubMedDate not supplied

[Dynamics of the development of different microorganisms in soil].

The dynamics of individual components from the complex of soil microorganisms (bacteria, fungi, actinomycetes) and the population of Stm. olivocinereus introduced into soil was studied by luminescent microscopy and inoculation. The population density maxima for individual components from the complex of soil microorganisms were shown to be separated in time suggesting a succession. Fungi developed at the first steps of succession and dominated in biomass over the remaining components of the complex. Bacteria and actinomycetes developed at the later steps of succession. Glucose addition stimulated still earlier growth of fungi (the maximal mycelium legth was registered by the second day) but had hardly any effect on the dynamics of other components of the complex.

Actinomyces↗