Biogenesis of antibiotics-viewing its history and glimpses of the future.

This review aims at comparing some historical data with the current situation in the study of biogenesis of natural compounds, antibiotics in the first place. Biogenesis of tetracyclines and cycloheximide and related compounds serves as example. Examples of molecular biological and bioinformatics methods used in the study of antibiotic biogenesis are described both in terms of its historical aspects and the current knowledge.

Lipidomics as an important key for the identification of beer-spoilage bacteria.

Electrospray ionization-tandem mass spectrometry (ESI-MS/MS) was used for characterizing intact plasmalogen phospholipid molecules in beer-spoilage bacteria. Identification of intact plasmalogens was carried out using collision-induced dissociation and the presence of suitable marker molecular species, both qualitative and quantitative, was determined in samples containing the anaerobic bacteria Megasphaera and Pectinatus. Using selected ion monitoring (SIM), this method had a limit of detection at 1 pg for the standard, i.e. 1-(1Z-octadecenyl)-2-oleoyl-sn-glycero-3-phosphoethanolamine and be linear in the range of four orders of magnitude from 2 pg to 20 ng. This technique was applied to intact plasmalogen extracts from the samples of contaminated and uncontaminated beer without derivatization and resulted in the identification of contamination of beer by Megasphaera and Pectinatus bacteria. The limit of detection was about 830 cells of anaerobic bacteria, i.e. bacteria containing natural cyclopropane plasmalogenes (c-p-19:0/15:0), which is the majority plasmalogen located in both Megasphaera and Pectinatus. The SIM ESI-MS method has been shown to be useful for the analysis of low concentration of plasmalogens in all biological samples, which were contaminated with anaerobic bacteria, e.g. juice, not only in beer. Significance and impact of the study: Electrospray ionization-tandem mass spectrometry (ESI-MS/MS) using collision-induced dissociation was used to characterize intact plasmalogen phospholipid molecules in beer-spoilage anaerobic bacteria Megasphaera and Pectinatus. Using selected ion monitoring (SIM), this method has a detection limit of 1 pg for the standard 1-(1Z-octadecenyl)-2-oleoyl-sn-glycero-3-phosphoethanolamine and is linear within four orders of magnitude (2 pg to 20 ng). The limit of detection was about 830 cells of bacteria containing natural cyclopropane plasmalogen (c-p-19:0/15:0). SIM ESI-MS method is useful for analyzing low concentrations of plasmalogens in biological samples contaminated with anaerobic bacteria, e.g. beer or juice.

Protective effect of Clostridium tyrobutyricum in acute dextran sodium sulphate-induced colitis: differential regulation of tumour necrosis factor-α and interleukin-18 in BALB/c and severe combined immunodeficiency mice.

One of the promising approaches in the therapy of ulcerative colitis is administration of butyrate, an energy source for colonocytes, into the lumen of the colon. This study investigates the effect of butyrate producing bacterium Clostridium tyrobutyricum on dextran sodium sulphate (DSS)-induced colitis in mice. Immunocompetent BALB/c and immunodeficient severe combined immunodeficiency (SCID) mice reared in specific-pathogen-free (SPF) conditions were treated intrarectally with C. tyrobutyricum 1 week prior to the induction of DSS colitis and during oral DSS treatment. Administration of DSS without C. tyrobutyricum treatment led to an appearance of clinical symptoms - bleeding, rectal prolapses and colitis-induced increase in the antigen CD11b, a marker of infiltrating inflammatory cells in the lamina propria. The severity of colitis was similar in BALB/c and SCID mice as judged by the histological damage score and colon shortening after 7 days of DSS treatment. Both strains of mice also showed a similar reduction in tight junction (TJ) protein zonula occludens (ZO)-1 expression and of MUC-2 mucin depression. Highly elevated levels of cytokine tumour necrosis factor (TNF)-α in the colon of SCID mice and of interleukin (IL)-18 in BALB/c mice were observed. Intrarectal administration of C. tyrobutyricum prevented appearance of clinical symptoms of DSS-colitis, restored normal MUC-2 production, unaltered expression of TJ protein ZO-1 and decreased levels of TNF-α and IL-18 in the descending colon of SCID and BALB/c mice, respectively. Some of these features can be ascribed to the increased production of butyrate in the lumen of the colon and its role in protection of barrier functions and regulation of IL-18 expression.

Trachydiscus minutus, a new biotechnological source of eicosapentaenoic acid.

The yellow-green alga Trachydiscus minutus (class Xanthophyta) was cultivated in a standard medium and in media without sulfur and nitrogen. Its yield after a 16-d cultivation reached 13 g dry mass per 1 L medium. The content of oligoenoic ('polyenoic') fatty acid (PUFA), i.e. eicosapentaenoic (EPA), was in excess of 35 % of total fatty acids; the productivity was thus 88 mg/L per d. This result makes the alga a very prospective organism that may serve as a new biotechnological source of single cell oil.

Identification of odorous compounds from nine fermentor-cultivated Streptomyces strains.

The chemical composition was determined of odors produced by nine strains of streptomycetes (Streptomyces aureofaciens, S. avermitilis, S. cinnamonensis, S. coelicolor, S. griseus, S. lividans, S. rimosus, S. spectabilis, S. virginiae) cultivated in a fermentor under similar cultivation conditions. GC-MS analysis identified more than twenty noteworthy volatile chemical individuals. The main components of the odor spectrum were geosmin and unique homologues of oxolones (dihydrofuranones), minor compounds included, e.g., pyrazine derivatives, acetoin and its homologues, aromatic esters, furan derivatives.

Structural analysis of a polysaccharide from Chlorella kessleri by means of gas chromatography-mass spectrometry of its saccharide alditols.

Interpretation of gas chromatographic-mass spectrometric data of oligosaccharide alditols was used to determine their structures and to derive the structure of a water soluble polysaccharide isolated from Chlorella kessleri. 1H- and 13C-NMR was employed to assess the configuration of glycosidic bonds and individual monosaccharides were assigned to the L or D series by means of gas chromatography of the acetylated (S)-2-butyl glycosides.

Relationship between volatile odorous substances and production of avermectins by Streptomyces avermitilis.

The time course of production of odorous compounds, i.e. geosmin and oxolones, and of avermectins was determined during the cultivation of S. avermitilis in flasks, 1- and 50-L fermentors. The amount of the antibiotics increased with increasing cultivation time up to more than 2 g/L while the concentration of geosmin rose to more than 4 mg/L. Cultivation without reflux condenser resulted in a lower product formation due to the higher stripping of geosmin. A relatively tight correlation was found between the production of geosmin and the production of avermectins. The production of oxolones peaked on cultivation days 3-5, the sum of oxolones being 60 microg/L. Subsequently, the production dropped below a measurable level. This can be explained as being due to the inhibition of oxolone production by geosmin.

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.

Metabolites produced by cyanobacteria belonging to several species of the family Nostocaceae.

This paper provides a comprehensive overview of metabolites, including lipids and lipid-like compounds, nitrogen metabolites, oligopeptides and amino acid derivatives, produced by cyanobacteria of the genera Anabaenopsis, Aphanizomenon, Aulosira, Cylindrospermopsis, Cylindrospermum, Nodularia, and Richelia of the family Nostocaceae.

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 %.

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.

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).

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.

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.

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.

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%).

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).

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).

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.

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.