Metabolic products of microorganisms

Rinamycin interfered with DNA-polymerase I of Escherichia coli in cell-free systems more effectively than actinomycin C. Its inhibitory action could be relieved by increasing the concentration of polymerase. The rinamycin concentrations that caused effective inhibition of the RNA-polymerase reaction in vitro were approximately 10 times higher than those required to inhibit the DNA-polymerase reaction in vitro.Derinamycin was as effective an inhibitor for the DNA-polymerase I reaction as actinomycin C, while having been stimulative for the RNA-polymerase reaction in cell-free systems of Escherichia coli. Its inhibitory action on DNA synthesis in vitro could be overcome by adding more DNA. In fact, spectral and antagonism studies suggested some sort of interaction between derinamycin and DNA.154. Mitteilung: U. Dähn, H. Hagenmaier, H. Höhne, W. A. König, G. Wolf, H. Zähner: Nikkomycin, ein neuer Hemmstoff der Chitinsynthese bei Pilzen. Arch. Microbiol. 107, 143–160 (1976).     

Metabolic products of microorganisms

Different derivatives of coprogen B (desacetyl coprogen) and coprogen were prepared to study their iron transport properties in Neurospora crassa arg-5, ota, aga. With increasing N-acyl chain length the rates of iron chelate uptake could significantly be enhanced in the order N-acetyl-Neurospora crassa. The results suggest that the coprogen molecule requires a special hydrophobic area for optimal orientation during uptake and iron release.134. Mitteilung: Hasenböhler, A., Kneifel, H., König, W. A., Zähner, H., Zeiler, H. J.: Stenothricin, ein neuer Hemmstoff der bakteriellen Zellwandsynthese. Arch. Microbiol. 99, 307–321 (1974).     

Metabolic products of microorganisms

Summary Boromycin, at a concentration of 0.05 g/ml inhibits the synthesis of protein, RNA and DNA in whole cells of Bacillus subtilis. It is being antagonised by surface active compounds and is being bound to lipoprotein. Binding of the boromycin within the cell especially takes place at the cytoplasmic membrane.The inhibitory effect to Bacillus subtilis is being reversed by high concentration of potassium salts (e.g. 0.2 m KCl). The reversion is specific of potassium salts. After the adding of boromycin a discharge of potassium ions from the cells can be observed. The K⁺-Na⁺-activated ATP-ase of the cytoplasmic membrane is not influenced by boromycin. On an artificial membrane of carbon tetrachloride boromycin shows a low selectivity for potassium ions compared with sodium and lithium ions.The degradation of boromycin through alkaline and acid hydrolysis leads to a loss of antibiotic activity, due to the splitting off the boric acid from the molecule.76. Information: W. Pache u. H. Zähner: Arch. Mikrobiol. 66, 281–288 (1969).     

Metabolic products of microorganisms

In the course of a screening for new metabolites from fungi we isolated a substance with antimicrobial activity from cultures of Aspergillus duricaulis (CBS 481.65) (Tü 679). It was antagonized by putrescine, spermidine, spermine, arginine, citrulline, lysine, ornithine, in higher concentration by asparagine and glutamine too. The effect of ethylenediaminetetraacetate on the susceptibility of Streptomyces viridochromogenes (Tü 57) and Bacillus subtilis ATCC 6051 to this antibiotic has been studied.The substance was characterized and identified as cyclopaldic acid.Abbreviations MIC minimum inhibitory concentration - tlc thinlayer chromatography Metabolic products of microorganisms. 166. M. Kappner, A. Hasenböhler, H. Zähner: Optimierung der Desferri-Ferricrocinbildung bei Aspergillus viridi-nutans Ducker & Thrower. Arch. Microbiol. 115, 323–331 (1977)     

Metabolic products of microorganisms

The effect of the nucleoside-peptide antibiotics nikkomycin Z, nikkomycin X, and polyoxin A was tested on chitosomal chitin synthetase from yeast cells of the dimorphic fungus Mucor rouxii. The K _i was 0.6 M for polyoxin A and 0.5 M for nikkomycin X; nikkomycin Z was slightly less inhibitory (K _i=3.5M). Whereas the minimum inhibitory concentrations of the nikkomycins for growth and germination were quite low (about 1M, or lower), polyoxin A displayed no antifungal activity against yeast cells and sporangiospores of the test organism, even when present in high concentrations. These results are discussed with respect to structure/activity relationships.Abbreviations MIC minimum inhibitory concentration (i.e. concentration required to completely suppress growth: cf. Drews, 1979) - GlcNAc N-acetyl-d-glucosamine - UDP-GlcNAc uridine 5-diphospho-N-acetyl-d-glucosamine Metabolic products of microorganisms. 202. H. P. Kaiser and W. Keller-Schierlein: Strukturaufklärung von Elaiophylin: Spektroskopische Untersuchungen und Abbau. Helv. Chim. Acta 64: 407–424 (1981)     

Metabolic products of microorganisms

1. The total nitrogen content of spores of Penicillium notatum increased during swelling and reached a maximum before germ-tubes were formed. It subsequently decreased during germ-tube formation until a constant value in hyphae was reached.
2. An increase in the protein content of the spores was found during swelling, followed by a decrease when germ-tubes were formed. After germination, the protein content increased again to a constant level in hyphae.
3. The content of total lipids steadily decreased during swelling of spores. It reached a minimum value in germinating spores, followed by a net accumulation during hyphal growth. Similar changes occurred in free lipids, phospholipids and the acetone-soluble lipids but not in bound lipids.
4. After an initial decrease during swelling, no further change took place in the neutral carbohydrates content of the spores at the time of germ-tube formation. An accumulation of neutral carbohydrates occurred during late hyphal extension.
5. The nucleic acid content increased sharply during swelling, and reached the highest value in swollen spores just prior to the initiation of germ-tube formation. Afterwards, its content steadily decreased during germ-tube formation and hyphae elongation.

     

L-苯丙氨酸生产的代谢工程研究

L-苯丙氨酸是一种重要的食品和医药中间体。工业上一般采用酶法和发酵法来生产L-苯丙氨酸。代谢工程的兴起,使得更加理性的改造菌株成为可能,这更加促进了发酵法的广泛应用。主要介绍了代谢工程在L-苯丙氨酸生产菌的改造中的应用情况,其中涉及苯丙氨酸生物合成途径中相关基因及其酶的调控、中央代谢途径的改造和芳香族氨基酸生物合成支路的修饰。并探讨了将来的发展前景。     

Metabolic products of microorganisms 181. Chitin synthase from fungi,a test model for substances with insecticidal properties

Chitin synthase from Coprinus cinereus (Schaeff. ex Fr.) S. F. Gray (= C. lagopus sensu Buller) was used as a model for chitin synthase from insects. The effect of dimilin (difluorobenzuron), captan (trichloromethylsulfonyl fungicide), kitazin P (organophosphorus ester fungicide) and parathion (organophosphorus insecticide) on the fungal enzyme was compared with the effect of nikkomycin (nucleoside-peptide antibiotic).Metabolic products of microorganisms. 180. M. Brufani, L. Celai, W. Keller-Schierlein, E. Pretsch: Revised structure of naphthomycin. J. Antibiot. (Tokyo) (in press)     

Metabolic activity of microorganisms in evaporites

Crystalline salt is generally considered so hostile to most forms of life that it has been used for centuries as a preservative. Here, we present evidence that prokaryotes inhabiting a natural evaporite crust of halite and gypsum are metabolically active while inside the evaporite for at least 10 months. In situ measurements demonstrated that some of these "endoevaporitic" microorganisms (probably the cyanobacterium Synechococcus Nageli) fixed carbon and nitrogen. Denitrification was not observed. Our results quantified the slow microbial activity that can occur in salt crystals. Implications of this study include the possibility that microorganisms found in ancient evaporite deposits may have been part of an evaporite community.     

Population organization and communication in microorganisms

This review concentrates on the history of the subfield of microbiology referred to as the population organization- and communication-related research direction (POCRRD). The focal points of POCRRD include intercellular interactions, information exchange between cells, and multicellular structures (colonies, biofilms, flocs, etc.). Special attention in this review is given to the contribution of Russian scientists to the development of POCRRD. In terms of POCRRD, microorganisms are viewed as social creatures that constantly communicate and form supraorganismic, intrinsically heterogeneous systems.     

Biodegradation of cellulosic materials: Substrates,microorganisms, enzymes and products

Cellulosic materials are the only renewable resources available in large quantities which need to be properly utilized to meet our needs of energy, chemicals, food and feed for a long-range solution. A variety of lignocellulosic materials are available and microorganisms capable of degrading either one or more of the three main constituents, viz. cellulose, hemicellulose and lignin have been studied. At least three different enzymes of the multicomponent cellulase system, i.e. cellobiohydrolase endo-glucanase and β-glucosidase are involved in the degradation of crystalline cellulose into glucose. Their mode of action and the manner in which they bring about hydrolysis of crystalline cellulose is discussed in detail. The involvement of parallel enzymes for hemicellulose degradation is also known to some extent but needs to be studied more elaborately, independently and in combination with cellulases. The potential of cellulosic biomass as a source of fuel and petroleum-sparing substances is also reviewed.     

Metabolic pathway of 3,6-anhydro-L-galactose in agar-degrading microorganisms

Recently, agarose-containing macroalgae have gained attention as possible renewable sources for bioethanol-production because of their high polysaccharide content. Complete hydrolysis of agarose produces two monomers, D-galactose (D-Gal) and 3,6-anhydro-L-galactose (L-AnG). However, at present, bioethanol yield from agarophyte macroalgae is low due to the inability of bioethanolproducing microorganisms to convert non-fermentable sugars, such as L-AnG, to bioethanol. Therefore, to increase the bioethanol productivity of agarophytes, it is necessary to determine how agar-degrading microorganisms metabolize L-AnG, and accordingly, construct recombinant microorganisms that can utilize both D-Gal and L-AnG. Previously, we isolated a novel microorganism belonging to a new genus, Postechiella marina M091, which hydrolyzes and metabolizes agar as the carbon and energy source. Here, we report a comparative genomic analysis of P. marina M091, Pseudoalteromonas atlantica T6c, and Streptomyces coelicolor A3(2), of the classes Flavobacteria, Gammaproteobacteria, and Actinobacteria, respectively. In this bioinformatic analysis of these agarolytic bacteria, we found candidate common genes that were believed to be involved in L-AnG metabolism. We then experimentally confirmed the enzymatic function of each gene product in the L-AnG cluster. The formation of two key intermediates, 2-keto-3-deoxy-L-galactonate and 2-keto-3-deoxy-D-gluconate, was also verified using enzymes that utilize these molecules as substrates. Combining bioinformatic analysis and experimental data, we showed that L-AnG is metabolized to pyruvate and D-glyceraldehyde-3-phosphate via six enzymecatalyzed reactions in the following reaction sequence: 3,6-anhydro-L-galactose → 3,6-anhydro-L-galactonate → 2-keto-3-deoxy-L-galactonate → 2,5-diketo-3-deoxy-L-galactonate → 2-keto-3-deoxy-D-gluconate → 2-keto-3-deoxy-6-phospho-D-gluconate → pyruvate + D-glyceraldehyde-3- phosphate. To our knowledge, this is the first report on the metabolic pathway of L-AnG degradation.     

Metabolic flux analysis and metabolic engineering of microorganisms

Recent advances in metabolic flux analysis including genome-scale constraints-based flux analysis and its applications in metabolic engineering are reviewed. Various computational aspects of constraints-based flux analysis including genome-scale stoichiometric models, additional constraints used for the improved accuracy, and several algorithms for identifying the target genes to be manipulated are described. Also, some of the successful applications of metabolic flux analysis in metabolic engineering are reviewed. Finally, we discuss the limitations that need to be overcome to make the results of genome-scale flux analysis more realistically represent the real cell metabolism.     

Metabolic engineering of flavonoids in plants and microorganisms

Over 9,000 flavonoid compounds have been found in various plants, comprising one of the largest families of natural products. Flavonoids are an essential factor in plant interactions with the environment, often serving as the first line of defense against UV irradiation and pathogen attacks. Flavonoids are also major nutritional compounds in foods and beverages, with demonstrated health benefits. Some flavonoids are potent antioxidants, and specific flavonoid compounds are beneficial in many physiological and pharmacological processes. Therefore, engineering of flavonoid biosynthesis in plants or in microorganisms has significant scientific and economical importance. Construction of biosynthetic pathways in heterologous systems offers promising results for large-scale flavonoid production by fermentation or bioconversion. Genomics and metabolomics now offer unprecedented tools for detailed understanding of the engineered transgenic organism and for developing novel technologies to further increase flavonoid production yields. We summarize some of the recent metabolic engineering strategies in plants and microorganisms, with a focus on applications of metabolic flux analysis. We are confident that these engineering approaches will lead to successful industrial flavonoid production in the near future.     

Colonial organization and intercellular communication of microorganisms

This review covers the modern concepts and recent data demonstrating the integrity and coherence of microbial populations (colonies, biofilms, etc.) as peculiar "super-organisms." Special attention is given to such relevant phenomena as apoptosis, bacterial altruism, quorum effects, collective differentiation of microbial cells, and the formation of population-level structures such as an extracellular matrix. Emphasis is placed on the channels in colonies and agents of intercellular communication in microbial populations. The involvement of a large number of evolutionarily conserved communicational facilities and patterns of intercellular interactions is underscored. Much attention is also given to the role of colonial organization and intercellular communication in parasite/commensal/symbiont-multicellular host organism systems.     

Metabolic products of microorganisms. 185. The anthraquinones of the Aspergillus glaucus group. I. Occurrence,isolation, identification and antimicrobial activity

The occurrence of emodin, erythroglaucin, physcion, physcion-9-anthrone, questin, catenarin, and catenarin-8-methyl ether in different species of the Aspergillus glaucus group (genus Eurotium) was investigated. So far catenarin-8-methyl ether (1, 4, 6-trihydroxy-8-methoxy-3-methylanthraquinone) has not been described as a natural product; it was therefore given the name rubrocristin. The chemical and physical properties of rubrocristin are reported. In addition a new violet pigment (C₁₆H₁₂O₅) was isolated and characterized by its MS-, IR- and UV-spectra.The antimicrobial properties of all substances were examined in the agar diffusion assay. Gram-positive bacteria were the most sensitive organisms and catenarin was the most active naturally occurring substance. Synthetically obtained 1, 4, 6, 8-tetrahydroxy-anthraquinone was slightly more active than catenarin, whereas rubrocristin showed no antibacterial activity.Abbreviations MIC Minimal inhibitory concentration - TLC Thin layer chromatography - PTLC Preparative thin layer chromatography Metabolic products of microorganisms. 184. H. Anke: On the mode of action of cladosporin. J. Antibiotics 32, 952–958 (1979)     

Metabolic products of microorganisms. 192. The anthraquinones of the Aspergillus glaucus group. II. Biological activity

From the mycelia of Aspergillus cristatus the following anthraquionic pigments were isolated: catenarin, emodin, erythroglaucin, rubrocristin, physcion, physcion-9-anthrone, questin, viocristin, and isoviocristin. The latter two do not belong to the 9, 10-anthraquinone series but to the 1,4-anthraquinones, and so far they have not been reported among naturally occurring quinones.Emodin, catenarin, viocristin, and isoviocristin snowed antibacterial activity with minimal inhibitory concentrations ranging from 1–10 g/ml. In Bacillus brevis catenarin and emodin inhibited the incorporation of uracil and leucine preferentially. At higher concentrations the incorporation of thymidine into the trichloroacetic acid-precipitable fraction of cells was also affected. In the presence of viocristin or isoviocristin all three macromolecular syntheses came to a halt. Rubrocristin, erythroglaucin, and physcion showed no significant inhibitory effects.In Ehrlich ascites carcinoma cells catenarin, emodin, and viocristin inhibited the incorporation of uridine and thymidine. The incorporation of leucine was hardly affected.In vitro, inhibition of DNA-dependent RNA polymerase from Escherichia coli by catenarin and to a lesser extent by emodin was observed, whereas rubrocristin (catenarin-8-methyl ether), physcion, and erythroglaucin were not active.Abbreviations MIC minimal inhibitory concentration - TCA trichloroacetic acid - ECA Ehrlich ascites carcinoma Metabolic Products of Microorganisms. 191. W. Keller-Schierlein und B. Joos; Über das 4-Oxohomotyrosin, ein Abbauprodukt des Echinocandins. Helv. Chim. Acta (in press)