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  • 1
    Digitale Medien
    Digitale Medien
    ENDANGERED ANTARCTIC ENVIRONMENTS (2004)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Microbiology 58 (2004), S. 649-690 
    Details
    ISSN: 0066-4227
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: The Antarctic continent harbors a range of specialized and sometimes highly localized microbial biotopes. These include biotopes associated with desiccated mineral soils, rich ornithogenic soils, glacial and sea ice, ice-covered lakes, translucent rocks, and geothermally heated soils. All are characterized by the imposition of one or more environmental extremes (including low temperature, wide temperature fluctuations, desiccation, hypersalinity, high periodic radiation fluxes, and low nutrient status). As our understanding of the true microbial diversity in these biotopes expands from the application of molecular phylogenetic methods, we come closer to the point where we can make an accurate assessment of the impacts of environmental change, human intervention, and other natural and unnatural impositions. At present, it is possible to make reasonable predictions about the physical effects of local climate change, but only general predictions on possible changes in microbial community structure. The consequences of some direct human impacts, such as physical disruption of microbial soil communities, are obvious if not yet quantitated. Others, such as the dissemination of nonindigenous microorganisms into indigenous microbial communities, are not yet understood.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.micro.57.030502.090811
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  • 2
    Digitale Medien
    Digitale Medien
    Bacterial community analysis of Indonesian hot springs (2001)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 200 (2001), S. 0 
    Details
    ISSN: 1574-6968
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: We report the first attempts to describe thermophilic bacterial communities in Indonesia's thermal springs using molecular phylogenetic analyses. 16S rRNA genes from laboratory cultures and DNA directly amplified from three hot springs in West Java were sequenced. The 22 sequences obtained were assignable to the taxa Proteobacteria, Bacillus and Flavobacterium, including a number of clades not normally associated with thermophily.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1574-6968.2001.tb10700.x
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  • 3
    Digitale Medien
    Digitale Medien
    A comparison of extracellular serine proteases from four strains of Thermus aquaticus (1987)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 43 (1987), S. 0 
    Details
    ISSN: 1574-6968
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: A comparison of extracellular proteases from New Zealand isolates of the genus Thermus demonstrated a number of minor but significant structural and functional differences. The comparison, based on molecular weights, isoelectric points, inhibitor responses, substrate specificity, pH optima and thermostability suggested that the four proteases were a closely related family.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1574-6968.1987.tb02115.x
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  • 4
    Digitale Medien
    Digitale Medien
    Uracil-DNA glycosylase activities in hyperthermophilic micro-organisms (1996)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 143 (1996), S. 0 
    Details
    ISSN: 1574-6968
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Abstract Hyperthermophiles exist in conditions which present an increased threat to the informational integrity of their DNA, particularly by hydrolytic damage. As in mesophilic organisms, specific activities must exist to restore and protect this template function of DNA. In this study we have demonstrated the presence of thermally stable uracil-DNA glycosylase activities in seven hyperthermophiles; one bacterial: Thermotoga maritima, and six archaeal: Sulfolobus solfataricus, Sulfolobus shibatae, Sulfolobus acidocaldarius, Thermococcus litoralis, Pyrococcus furiosus and Pyrobaculum islandicum. Uracil-DNA glycosylase inhibitor protein of the Bacillus subtilis bacteriophage PBS1 shows activity against all of these, suggesting a highly conserved tertiary structure between hyperthermophilic and mesophilic uracil-DNA glycosylases.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1574-6968.1996.tb08491.x
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  • 5
    Digitale Medien
    Digitale Medien
    Extracellular α-amylase from Thermus filiformis Ork A2: purification and biochemical characterization (1998)
    Springer
    Extremophiles 2 (1998), S. 23-32 
    Details
    ISSN: 1433-4909
    Schlagwort(e): Key wordsThermus filiformis ; α-Amylase ; Extracellular ; Purification ; Properties ; Thermostability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract An extracellular α-amylase produced by the thermophilic bacterium Thermus filiformis Ork A2 was purified from cell-free culture supernatant by ion exchange chromatography. The molecular mass was estimated to be 60 000 Da by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The enzyme was rich in both basic and hydrophobic amino acids, presenting the following NH2-terminal amino acid sequence: Thr-Ala-Asp-Leu-Ile-Val-Lys-Ile-Asn-Phe. Amylolytic activity on soluble starch was optimal at pH 5.5–6.0 and 95°C, and the enzyme was stable in the pH range of 4.0–8.0. Calcium enhanced thermostability at temperatures above 80°C, increasing the half-life of activity to more than 8 h at 85°C, 80 min at 90°C, and 19 min at 95°C. Ethylenediaminetetraacetic acid (EDTA) inhibited amylase activity, the inhibition being reversed by the addition of calcium or strontium ions. The α-amylase was also inhibited by copper and mercuric ions, and p-chloromercuribenzoic acid, the latter being reversed in the presence of dithiothreitol. Dithiothreitol and β-mercaptoethanol activated the enzyme. The α-amylase exhibited Michaelis-Menten kinetics for starch, with a K m of 5.0 mg·ml−1 and k cat/K m of 5.2 × 105 ml·mg−1 s−1. Similar values were obtained for amylose, amylopectin, and glycogen. The hydrolysis pattern was similar for maltooligosaccharides and polysaccharides, with maltose being the major hydrolysis product. Glucose and maltotriose were generated as secondary products, although glucose was produced in high levels after a 6-h digestion. To our knowledge this is the first report of the characterization of an α-amylase from a strain of the genus Thermus.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s007920050039
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  • 6
    Digitale Medien
    Digitale Medien
    Characterization of an inducible nitrilase from a thermophilic bacillus (1999)
    Springer
    Extremophiles 3 (1999), S. 283-291 
    Details
    ISSN: 1433-4909
    Schlagwort(e): Key words Benzonitrile ; Nitrile ; Nitrilase ; Thermophilic ; Thermostable
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Nitrilase activity was induced in the thermophilic bacterium Bacillus pallidus strain Dac521 by growth on benzonitrile-supplemented minimal medium. The enzyme had a subunit relative molecular mass of 41 kDa but was purified as a complex with a putative GroEL protein (total M r, 600 kDa). The enzyme catalyzed the hydrolysis of aliphatic, aromatic, and heterocyclic nitriles with widely varying k cat/K M values, primarily the result of differences in substrate affinity. Of the nitriles tested, 4-cyanopyridine was hydrolyzed at the fastest rate. Substitution of benzonitrile at the meta or para position either had no effect on catalytic rate or enhanced k cat, while ortho-substitution was strongly inhibitory, probably because of steric hindrance. The effect of catalytic inhibitors was consistent with the presence of active site thiol residues although activity was little affected by putative thiol reagents such as iodoacetate, iodoacetamide, and N-methylmaleimide. Enzymatic activity was constant between pH 6 and 9 with an optimum at pH 7.6. The optimal temperature for activity was 65°C with rapid activity loss at higher temperatures. The purified nitrilase-GroEL complex had the following half-lives of activity: 8.4 h at 50°C, 2.5 h at 60°C, 13 min at 70°C, and less than 3 min at 80°C.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s007920050129
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  • 7
    Digitale Medien
    Digitale Medien
    Detecting human bacterial contamination in Antarctic soils (2000)
    Springer
    Polar biology 23 (2000), S. 644-650 
    Details
    ISSN: 1432-2056
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The presence of non-indigenous microbial contaminants resulting from human faecal contamination of old and currently occupied base and field camp sites in South Victoria Land, Antarctica, was assessed by PCR amplification of extracted soil DNA using species-specific PCR primers. Positive controls (samples recovered from the environs of Scott Base, including the sewage outfall) gave strong signals with Escherichia coli primers whereas Clostridium clostridiiforme primers yielded a signal only with the sewage outfall sample. A comparison was made of PCR amplification results from samples from the abandoned Canada Glacier camp site, the Lake Fryxell summer camp site, the Cape Bird Adelie penguin colony and pristine sites from relatively inaccessible regions of the Taylor Valley. Results indicated a possible residual level of E. coli contamination in the abandoned Canada Glacier camp site, but no significant contamination of the currently occupied Lake Fryxell camp site. These data may provide indirect evidence for improved awareness and standards of waste handling and disposal over the past two decades of Dry Valley field research.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s003000000137
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  • 8
    Digitale Medien
    Digitale Medien
    The search for the ideal biocatalyst (2002)
    [s.l.] : Nature Publishing Group
    Nature biotechnology 20 (2002), S. 37-45 
    Details
    ISSN: 1546-1696
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: [Auszug] While the use of enzymes as biocatalysts to assist in the industrial manufacture of fine chemicals and pharmaceuticals has enormous potential, application is frequently limited by evolution-led catalyst traits. The advent of designer biocatalysts, produced by informed selection and mutation through ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/nbt0102-37
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  • 9
    Digitale Medien
    Digitale Medien
    Complementation of a pgk deletion mutation in Saccharomyces cerevisiae with expression of the phosphoglycerate-kinase gene from the hyperthermophilic Archaeon Sulfolobus solfataricus (1996)
    Springer
    Current genetics 29 (1996), S. 594-596 
    Details
    ISSN: 1432-0983
    Schlagwort(e): Key words Yeast ; Heterologous gene expression ; Sulfolobus ; Hyperthermophile phosphoglycerate kinase ; Archaea
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  The gene encoding phosphoglycerate kinase (PGK) from the Archaeon Sulfolobus solfataricus, an organism growing optimally at 87 °C, was inserted into a yeast expression vector under the control of the galactose-inducible GAL1 yeast promoter. This vector was then transformed into a pgk::TRP1 yeast mutant, a strain inhibited for growth on galactose or glucose due to its lack of PGK enzyme. Slow-growing transformants were obtained on galactose plates at 37 °C, but not 28 °C. These transformants contained low levels of transcripts of the heterologous gene and low amounts of thermostable PGK activity. Weak expression of the hyperthermophile gene in yeast, a mesophile, therefore enabled complementation of the yeast pgk defect at 37 °C but not at 28 °C.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002940050091
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  • 10
    Digitale Medien
    Digitale Medien
    Complementation of apgk deletion mutation inSaccharomyces cerevisiae with expression of the phosphoglycerate-kinase gene from the hyperthermophilic ArchaeonSulfolobus solfataricus (1996)
    Springer
    Current genetics 29 (1996), S. 594-596 
    Details
    ISSN: 1432-0983
    Schlagwort(e): Yeast ; Heterologous gene expression ; Sulfolobus ; Hyperthermophile phosphoglycerate kinase ; Archaea
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The gene encoding phosphoglycerate kinase (PGK) from the ArchaeonSulfolobus solfataricus, an organism growing optimally at 87°C, was inserted into a yeast expression vector under the control of the galactose-inducibleGAL1 yeast promoter. This vector was then transformed into apgk::TRP1 yeast mutant, a strain inhibited for growth on galactose or glucose due to its lack of PGK enzyme. Slow-growing transformants were obtained on galactose plates at 37°C, but not 28°C. These transformants contained low levels of transcripts of the heterologous gene and low amounts of thermostable PGK activity. Weak expression of the hyperthermophile gene in yeast a mesophile, therefore enabled complementation of the yeastpgk defect at 37°C but not at 28°C.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02426966
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