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  • 1
    Electronic Resource
    Electronic Resource
    Detecting human bacterial contamination in Antarctic soils (2000)
    Springer
    Polar biology 23 (2000), S. 644-650 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003000000137
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  • 2
    Electronic Resource
    Electronic Resource
    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
    Keywords: Key words Yeast ; Heterologous gene expression ; Sulfolobus ; Hyperthermophile phosphoglycerate kinase ; Archaea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002940050091
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  • 3
    Electronic Resource
    Electronic Resource
    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
    Keywords: Yeast ; Heterologous gene expression ; Sulfolobus ; Hyperthermophile phosphoglycerate kinase ; Archaea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02426966
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  • 4
    Electronic Resource
    Electronic Resource
    Characterization of an inducible nitrilase from a thermophilic bacillus (1999)
    Springer
    Extremophiles 3 (1999), S. 283-291 
    Details
    ISSN: 1433-4909
    Keywords: Key words Benzonitrile ; Nitrile ; Nitrilase ; Thermophilic ; Thermostable
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007920050129
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  • 5
    Electronic Resource
    Electronic Resource
    Extracellular α-amylase from Thermus filiformis Ork A2: purification and biochemical characterization (1998)
    Springer
    Extremophiles 2 (1998), S. 23-32 
    Details
    ISSN: 1433-4909
    Keywords: Key wordsThermus filiformis ; α-Amylase ; Extracellular ; Purification ; Properties ; Thermostability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007920050039
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