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  • 1
    Electronic Resource
    Electronic Resource
    Effects on microbial activity by extraction of indigenous cells from soil slurries (1996)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology ecology 21 (1996), S. 0 
    Details
    ISSN: 1574-6941
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract: Possible effects on the physiological activity and culturability of soil microorganisms by different soil dispersion procedures, and effects on activity caused by extracting bacteria from soil, were investigated. There was no apparent difference in cfu's with dispersion of a silty loam soil and a loamy sand soil with pyrophosphate as compared to dispersion in NaCl. Substrate-induced respiration was reduced in the silty loam soil, and methanol oxidation was reduced in the loamy sand soil with dispersion in pyrophosphate, and the soil pH was irreversibly increased by the treatment. Extracted bacterial fractions had lower numbers of culturable cells as percentage of the total number of bacteria in each fraction, lower respiration rates and no methanol oxidation activity as compared to the soil slurry both before and after extraction. The physiological activity was apparently not affected by the number of cells extracted. This indicates that the increased extraction rate of indigenous soil bacteria obtained by effective disruption of aggregates and detachment of cells from surfaces, only results in increased extraction of cells that have been physiologically changed as a result of the extraction process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6941.1996.tb00349.x
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  • 2
    Electronic Resource
    Electronic Resource
    Archaeal communities in High Arctic wetlands at Spitsbergen, Norway (78°N) as characterized by 16S rRNA gene fingerprinting (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology ecology 53 (2005), S. 0 
    Details
    ISSN: 1574-6941
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Emissions of the greenhouse gas methane from Arctic wetlands have been studied extensively, though little is known about the ecology and community structure of methanogenic archaea that catalyze the methane production. As part of a project addressing microbial transformations of methane in Arctic wetlands, we studied archaeal communities in two wetlands (Solvatnet and Stuphallet) at Spitsbergen, Norway (78°N) during two summer seasons. Directly extracted peat community DNA and enrichment cultures of methanogenic archaea were analyzed by nested PCR combined with denaturing gradient gel electrophoresis and subsequent sequencing of 16S rRNA gene fragments. Sequences affiliated with Methanomicrobiales, Methanobacteriaceae, Methanosaeta and Group I.3b of the uncultured crenarchaeota were detected at both sites. Sequences affiliated with Methanosarcina were recovered only from the site Solvatnet, while sequences affiliated with the euryarchaeotal clusters Rice Cluster II and Sediment 1 were detected only at the site Stuphallet. The phylogenetic affiliation of the recovered sequences suggested a potential of both hydrogenotrophic and acetoclastic methanogenesis at both sites. At Solvatnet, there were clear temporal trends in the archaeal community structure over the Arctic summer season. The archaeal community composition was significantly affected by factors influencing the activity of the overall bacterial community, as measured by in situ emissions of CO2. Methane emissions at both sites were influenced more by peat temperatures and thaw depth than by the archaeal community structure. Enrichment cultures for methanogenic archaea determined that most of the methanogens detected directly in peat could grow in culture at 10 °C. Culture based biases were indicated in later enrichment steps by the abundant growth of a Methanosarcina strain that was not detected directly in peat samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/j.femsec.2005.01.004
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  • 3
    Electronic Resource
    Electronic Resource
    Soil bacterial DNA and biovolume profiles measured by flow-cytometry (1993)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 102 (1993), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Flow-cytometry was used to measure cell volumes and DNA contents of single cells in cultures of soil bacteria during exponential growth and starvation conditions. DNA was measured after staining with mitramycin/ethidium bromide. The measurement of DNA was calibrated with rifampicin-treated cells of E. coli containing even numbers of genomes per cell. Cell volumes were assessed by scatter light measurements. Constant DNA to biovolume relations over a range of cell sizes were found for each of the bacteria at exponential growth, and DNA contents per cell varied over a range equivalent to 1–4 genomes per cell. At generation times of 1.0–1.5 h, two genomes were registered as a mean. After starvation of washed cells in a salt solution (24 hrs), a fraction of the cells in each culture had DNA contents equivalent to 1 genome, but significant fractions retained DNA contents equivalent to 2–4 genomes. Attempts to create cells with even numbers of genomes per cell by treatment with rifampicin was successful on an Acinetobacter sp. In contrast, the response to rifampicin was less clear for Pseudomonas fluorescens and P. chlororaphis, and unclear for the gram positive bacteria isolated from soil. The mean decrease in biovolume upon starvation was 4.1 times (range 1.3–8.1 times) and larger than the mean decrease in DNA content of 1.8 (range 1.3–2.7 times). Cell volume determinations by measurements of scatter light was compared with volume determinations by fluorescence microscopy. The amounts of scatter light per volumes was variable, not only did we find large differences between bacterial types, but also between starving and exponentially growing cells of the same isolate. In order to use light scatter as a measure of biovolume, internal standards has to be chosen of comparable size and surface properties as to soil bacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1993.tb05804.x
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  • 4
    Electronic Resource
    Electronic Resource
    Triterpeneglycosides as Inhibitors of Fungal Growth and Metabolism (1974)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 30 (1974), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Aescin in phosphate buffer reduced, to some extent, the production of 14CO2 from uniformly labelled glucose in mycelia of Ophiobolus graminis and Neurospora crassa, whereas aescin in succinate buffer had no effect. The enzymatic hydrolysis of sucrose was, however, severely affected, no production of 14CO2 from labelled sucrose being found after treatment of mycelia of O. graminis with 100 mg/l of aescin and N. crassa with 300 mg/l for 90 and 300 min, respectively. In Aspergillus niger the production of 14CO2 from glucose or sucrose was not affected. The ATPase in whole cells and isolated plasma membranes was not inhibited by the aescin treatment, on the contrary, the ATPase in whole cells of N. crassa was somewhat stimulated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1974.tb03656.x
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  • 5
    Electronic Resource
    Electronic Resource
    Triterpeneglycosides as Inhibitors of Fungal Growth and Metabolism 8. Induced Leakage of Nucleotide Materials (1975)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 33 (1975), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Addition of aescin to mycelia of Ophiobolus graminis and Neurospora crassa induced leakage of ribonucleotide material together with pentose phosphate or pentose.In O. graminis a rapid release of mono- and dinucleotides together with nucleosides and pentose occurred. In addition some oligonucleotides were released during the first 30 min of the treatment. A slow leakage of polynucleotides was also observed.In N. crassa aescin induced only slight leakage during the first hour, and the mono- and dinucleotide leakage was actually decreasing. From that time on, however, a rapid release of mono- and dinucleotides together with nucleosides and pentose phosphate or pentose was observed. Only small amounts of poly- and oligonucleotides leaked and the cell content of oligonucleotides seemed to be released only during the last hour of the treatment period.In Aspergillus niger, which was insensitive to the inhibitor, aescin only induced leakage of pentose or pentose phosphate and small amounts of mono- and dinucleotides.Loss of viability in mycelia of O. graminis and N. crassa seemed to be correlated with the loss of oligonucleotides from the cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1975.tb03769.x
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  • 6
    Electronic Resource
    Electronic Resource
    Triterpeneglycosides as Inhibitors of Fungal Growth and Metabolism 6. The Effect of Aescin on Fungi with Reduced Sterol Contents (1973)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 29 (1973), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The amount of sterols in the mycelia of Ophiobolus gra-minis and Neurospora crassa was reduced by cultivating the fungi in the presence of inhibitors of the sterol synthesis. The hypocholesteraemic compounds β-diethylaminoethyl-(2.2-diphenylpentanoate) hydrochloride (SK & F 525-A) and 2.2-diphenyl -1 -(β- dimethylaminoethoxy)pentane hydrocchloride (SK & F 3301-A) were particularly effective in reducing the sterol contents. At the same time, the growth yield was reduced. Aescin had a reduced inhibitory effect on the radial growth of the mycelia with decreased sterol contents, the leakage of UV-absorbing substances and K+ ions was reduced to small amounts, and the inhibition of the K+ uptake was nullified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1973.tb03082.x
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  • 7
    Electronic Resource
    Electronic Resource
    Triterpeneglycosides as Inhibitors of Fungal Growth and Metabolism (1971)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 25 (1971), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A venacin, the resistance factor in oat roots against Ophio-bolus graminis var. graminis, and a related triterpeneglycoside, aescin, induced a rapid release of K+ from mycelia of Opbio-bolus graminis and Neurospora crassa, suspended in phosphate buffer. N. crassa also released Mg2+ whereas no outflux of Mg2+ was found from O. graminis.The inhibitors induced a release of inorganic phosphate into acetate buffer from Neurospora crassa. The amount of inorganic phosphate in the mycelia decreased when O. graminis and N. crassa were treated with the inhibitors in phosphate buffer. In other media the inhibitors had weak or no effects on the ion contents of the mycelia.The effect of aescin was low in Aspergillus niger and nil in Pythium irregulare. However, high amounts of K+, Mg2+, and phosphate ions were lost to the medium when the mycelium of P. irregulare, washed with distilled water, was suspended in different buffers. The ions lost were reabsorbed during the experimental period. The leakage of ions indicates that the plasma membrane of the growth sensitive fungi is severely affected by the inhibitors, while a corresponding effect on the growth insensitive fungi does not take place.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1971.tb01429.x
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  • 8
    Electronic Resource
    Electronic Resource
    Methoxyhydroquinone, a Growth Inhibitor of Ophiobolus graminis, in Leaves of Oat Seedlings (1971)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 24 (1971), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A methanol extract of leaves of oat seedlings grown in sand cultures in the dark contained a compound which inhibited the growth of Ophiobolus graminis. The inhibitory factor was isolated and proved to be present in the plant as methoxyhydroquinone glucoside. The glucoside was readily hydrolysed to the corresponding aglucone. The methoxyhydroquinone, or possibly its oxydation product, methoxy-P-benzoquinone, was inhibitory to both Ophiobolus graminis var. graminis and Ophiobolus graminis var. avenae, whereas Fusarmm oxysporum var. lycopcrsici was not affected. Synthetic methoxyhydroquinone at 80 mg/l gave a 100% inhibition of Ophiobolus graminis var. graminis. After being exposed to 80 mg/l of the inhibitor for 24 h the mycelium was unable to initiate growth when transferred to a fresh nutrient solution. Only extracts from young leaves showed inhibitory activity, extracts from mature leaves giving no inhibition. The hydroquinone, or its glucoside, was not detected in roots of young seedlings, where avenacin was the only antifungal compound present.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1971.tb06711.x
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  • 9
    Electronic Resource
    Electronic Resource
    Triterpeneglycosideg as Inhibitors of Fungal Growth and Metabolism (1973)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 28 (1973), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Ergosterol was found to be the main sterol in the mycelia of Opbiobolus graminis, Neurospora crassa, and Aspsrgillus niger, A correlation was found between the amount of sterols in the mycelia of different fungi and the inhibitory effect of aescin. Aescin treatment caused a reduction of the amount of extractable sterols in the mycelia. The sterols seemed to be located mainly in the plasma membranes, and only trace amounts were Found in the mitochondrial membranes.The relative amount of sterols in the plasma membrane was found to be higher in O. graminis than in N. crassa and A. niger.Ca2+ interfered with the interaction, of sterols and aescin. In N. crassa the decreased inhibitory effect of aescin in the presence of Ca2+ was due to the reduced binding of the inhibitor to the sterols in the plasma membrane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1973.tb08598.x
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  • 10
    Electronic Resource
    Electronic Resource
    Aromatic Substances in Leaves of Populus tremula as Inhibitors of Mycorrhizal Fungi (1971)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 25 (1971), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The inhibitory principles of aqueous extracts of aspen leaves, acting upon mycorrhizal fungi of forest trees, were isolated by extraction with ethyl acetate and chromatography on silicic acid. Two inhibitors were identified as benzoic acid and catechol by gas chromatography and mass spectrometry. When added to a synthetic medium, these substances had a strong inhibitory effect on the growth of different Boletus-species and a weaker inhibitory effect on litter-decomposing Marasmius-species. When the fraction of the extract which was not soluble in ethyl acetate was included in the medium, the aromatic compounds still inhibited the mycorrhizal fungi while the growth of the litter-decomposers was stimulated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1971.tb01100.x
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