PubMed Health⌕ Search

Biomedical subjects

T Rezanka

Publications and source records attributed to T Rezanka.

At least 19 recordsLinked to original sources
PubMed2006

Adaptive changes in fatty acids of E. coli strains exposed to a quaternary ammonium salt and an amine oxide.

Resistant strains of Escherichia coli were obtained by stepwise cultivation in media with increasing concentration of antimicrobially active 1-(methyldodecyl)dimethylamine oxide and 1-(methyldodecyl)trimethylammonium bromide. Adaptive changes were determined in the fatty-acid (FA) composition in an isolated lipopolysaccharide sample from the outer membrane of these strains. The composition of this FA mixture from adapted strains was compared with that of FA from a sensitive strain. The differences were found in level of palmitic, heptadecanoic, heptadecenoic, heptadecadienoic and nonadecenoic acids. In addition, the adapted strains differed from each other in the content of myristic, pentadecanoic, stearic and linoleic acids.

Adaptation, Physiological↗
PubMed2006

Use of the industrial yeast Candida utilis for cadmium sorption.

The sorption ability of Candida utilis biomass for cadmium ions with accumulating competence of dried cells and cells in alginate was compared. After an optimization of process conditions (pH 5.5, biomass concentration 1 g/L and c0 50 mg/L), the cadmium sorption capacity of dried yeast biomass was perceptibly higher than that of the other tested adsorbents. Considering the sorption of the dried yeast biomass equal to 100 %, the cells in alginate reached 86 % while native cells showed only 42 %.

Adsorption↗
PubMed2005

Removal of copper ions from dilute solutions by Streptomyces noursei mycelium. Comparison with yeast biomass.

Sorption properties of Streptomyces noursei mycelium for copper ions were compared with the accumulation competence of dried and native yeast (Candida utilis) biomass. The copper sorption capacity of S. noursei after optimization was found to be higher than that of the two other adsorbents (dried yeast biomass 82 %, native Candida cells 48 % of the sorption capacity of the S. noursei mycelium).

Adsorption↗
PubMed2005

Metabolites produced by nitrogen-fixing Nostoc species.

This paper provides a comprehensive overview of metabolites, including lipids and lipid-like compounds, boron-containing macrocycles, arsenolipids, oligopeptides and amino acid derivatives, produced by cyanobacteria of the genus Nostoc.

Amino Acids↗
PubMed2004

Lincomycin, clindamycin and their applications.

Lincomycin and clindamycin are lincosamide antibiotics used in clinical practice. Both antibiotics are bacteriostatic and inhibit protein synthesis in sensitive bacteria. They may even be bactericidal at the higher concentrations that can be reached in vivo. Clindamycin is usually more active than lincomycin in the treatment of bacterial infections, in particular those caused by anaerobic species; and it can also be used for the treatment of important protozoal diseases, e.g. malaria, most effectively in combination with primaquine. Resistance to lincomycin and clindamycin may be caused by methylation of 23S ribosomal RNA, modification of the antibiotics by specific enzymes or active efflux from the periplasmic space.

Animals↗
PubMed2004

Natural microbial UV radiation filters--mycosporine-like amino acids.

Ozone depletion by anthropogenic gases has increased the atmospheric transmission of solar ultraviolet-B radiation (UV-B, 280-315 nm). There is a logical link between the natural defenses of terrestrial and marine organisms against UV radiation and the prevention of UV-induced damage to human skin. UV light degrades organic molecules such as proteins and nucleic acids, giving rise to structural changes that directly affect their biological function. These compounds offer the potential for development of novel UV blockers for human use. The biological role of mycosporine-like amino acids (MAAs) and scytonemin as a defense against solar radiation in organisms, together with their structure, synthesis, distribution, regulation and effectiveness, are reviewed in this article. This review points to the role of MAAs as a natural defense against UV radiation.

Amino Acids↗
PubMed2003

Lincomycin, cultivation of producing strains and biosynthesis.

Lincomycin and its derivatives are antibiotics exhibiting biological activity against Gram-positive bacteria. The semi-synthetic chlorinated lincomycin derivative is used in clinical practice. The chemical structure of lincosamide antibiotics, cultivation of producing strains and analytical procedures used for separation and isolation of these compounds are described in this review. Biosynthesis of lincomycin and related compounds and its genetic control are briefly discussed.

Biomass↗
PubMed2003

Biodegradable plastics from renewable sources.

Plastic waste disposal is a huge ecotechnological problem and one of the approaches to solving this problem is the development of biodegradable plastics. This review summarizes data on their use, biodegradability, commercial reliability and production from renewable resources. Some commercially successful biodegradable plastics are based on chemical synthesis (i.e. polyglycolic acid, polylactic acid, polycaprolactone, and polyvinyl alcohol). Others are products of microbial fermentations (i.e. polyesters and neutral polysaccharides) or are prepared from chemically modified natural products (e.g., starch, cellulose, chitin or soy protein).

Bacteria↗
PubMed2003

Fatty acid composition of six freshwater wild cyanobacterial species.

Hydroxy, n-saturated, branched, dioic, and unsaturated fatty acids in six freshwater wild cyanobacteria (Chroococcus minutus, Lyngbya ceylanica, Merismopedia glauca, Nodularia sphaerocarpa, Nostoc linckia, and Synechococcus aeruginosus) collected from different lakes and springs of Israel have been identified by gas chromatography-mass spectrometry (GC-MS).

Bacterial Typing Techniques↗
PubMed2003

Sterol compositions of the filamentous nitrogen-fixing terrestrial cyanobacterium Scytonema sp.

Thirteen unsaturated sterols were identified by gas chromatography--mass spectrometry using serially-coupled capillary columns from the filamentous nitrogen-fixing terrestrial cyanobacterium Scytonema sp. isolated from the microbial community of cyanobacterial on 'Black Cover' biofilms limestone walls in Jerusalem. The dominant sterols were cholest-5-en-3 beta-ol (18.9%), 3 beta-methoxycholest-5-ene (16.2%) and 3 beta-acetoxycholest-5-ene (11.2%).

Biofilms↗
PubMed2003

Polar lipids and fatty acids of three wild cyanobacterial strains of the genus Chroococcidiopsis.

The occurrence of n-saturated, branched, and unsaturated fatty acids of 3 wild terrestrial strains of the genus Chroococcidiopsis (Order Chroococcales): C. supralittoralis, C. umbratilis, and C. versatilis collected from Lake Kinneret, Dead Sea, and Ein Kerem (Jerusalem) was investigated and individual compounds identified by gas chromatography-mass spectrometry. Polar lipids also were examined. Among polar lipids (studied using two-dimensional thin-layer chromatography) were as major glycolipids isolated: monogalactosyl-diacylglycerols, digalactosyl-diacylglycerols, 6-sulfoquinovosyl-diacylglycerols and phosphatidylglycerol. Nonphosphorus betaine-containing lipid, viz. N,N,N-trimethylhomoserin-4-O-yl-diacylglycerol, was found for the first time in cyanobacterial species.

Chromatography, Thin Layer↗
PubMed2002

Identification of Streptomyces odor spectrum.

The chemical composition of odors produced by nine strains of Streptomyces was determined. Strains Streptomyces aureofaciens, S. avermitilis, S. cinamomensis, S. coelicolor, S. griseus, S. lividans, S. rimosus, S. spectabilis, S. virginiae (as representatives of producers of biologically active compounds) were cultivated at the same time statically in dishes and in shaken flasks at similar cultivation conditions. According to the GC-MS analysis of odor compounds, more than twenty noteworthy volatile chemical individuals were identified. As the main component of odor spectrum geosmin and homologues of oxolones (dihydrofuranones) were found; the other compounds (pyrazine derivatives, acetoin and its homologues, aromatic esters, furan derivatives, etc.) were in minority.

Furans↗
PubMed2002

Compounds isolated at the Institute of Microbiology in 1989-2001 and future trends.

A total of 307 new compounds, natural, semisynthetic or synthetic, were isolated at the Institute of microbiology during the last twelve years. Due to the development of separation (chromatographic) methods and of analytical methods used to determine the chemical structure of these compounds, i.e. NMR, MS and X-ray diffraction, many new metabolites could be described.

Amino Acid Sequence↗
PubMed2001

Chromatography of long chain alcohols (polyprenols) from animal and plant sources.

This paper provides a comprehensive overview of existing chromatographic methods for the analysis of long chain alcohols (polyprenols) from animal and plant sources. After a brief introductory discussion on the biological aspects of the polyprenols, the review focuses on various techniques for the isolation, purification, chromatographic separation and detection of polyprenols.

Alcohols↗
PubMed2001

Further glucosides of lichens' acids from Central Asian lichens.

Eight compounds isolated from an extract of Central Asian lichens comprised new glucosides having murolic, protoconstipatic and allo-murolic acids as the aglycones and a saccharide moiety linked at C-18 made up of four glucoses. The structures were elucidated using extensive spectroscopic analysis (1D and 2D NMR, MS, IR, UV and CD) and by chemical methods.

Chromatography, High Pressure Liquid↗
PubMed2001

Polyhalogenated homosesquiterpenic fatty acids from Plocamium cartilagineum.

We describe the composition of novel polyhalogenated homosesquiterpenic acids from the red alga Plocamium collected during summer on Maltese Islands and Corsica. The compounds, predominantly derivatives with unique groups (bromine, chlorine, and diene), were identified by means of 1H and 13C NMR, MS, IR and UV spectra.

Biological Factors↗