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  • Articles  (3)
  • Articles: DFG German National Licenses  (3)
  • bottle test  (2)
  • Keywords: keratinase; gene cloning; gene expression; Bacilli
  • Biology  (3)
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  • Articles  (3)
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  • Articles: DFG German National Licenses  (3)
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  • 1
    Electronic Resource
    Electronic Resource
    Algal bioassays to determine toxicity of metal mixtures (1980)
    Springer
    Hydrobiologia 74 (1980), S. 199-208 
    Details
    ISSN: 1573-5117
    Keywords: metals ; toxicity ; algal assay ; bottle test ; algae ; Chlorella fusca ; Ankistrodesmus bibraianum ; Scenedesmus quadricauda
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The shortcomings of many established toxicity criteria for metals have resulted from a simplification of bioassays performed with single metals. A more comprehensive approach was needed to diagnose the effects of metal mixtures on aquatic organisms. Using Chlorella, Ankistrodesmus and Scenedesmus as test organisms, we experimented on a number of factors which affected metal toxicity bioassays. These included metal interactions, algal competitions, species sensitivities, the ratio of an excess metal to other metals and nutrient levels. An alternative technique was finally established which involved an evaluation of individual assays of Chlorella and Ankistrodesmus in separate media and a tissue-metal analysis on Chlorella. Chlorella fusca, commonly found in lakes with high metal concentrations, showed high tolerance to mixed-metal solutions, while Ankistrodesmus proved to be very sensitive. By determining the maximum yield ratio between Ankistrodesmus and Chlorella (i.e. the A/Ch ratio) it was possible to compare the toxic strength of harmful metals according to an established standard curve of A/Ch ratio versus mixed-metal concentrations. The levels of tissue-metal analysed in Chlorella also gave some indication as to which metals were responsible for the toxicity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00008753
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Expression of the Bacillus licheniformis PWD-1 keratinase gene in B. subtilis (1997)
    Springer
    Journal of industrial microbiology and biotechnology 19 (1997), S. 134-138 
    Details
    ISSN: 1476-5535
    Keywords: Keywords: keratinase; gene cloning; gene expression; Bacilli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The kerA gene which encodes the enzyme keratinase was isolated from the feather-degrading bacterium Bacillus licheniformis PWD-1. The entire gene, including pre-, pro- and mature protein regions, was cloned with Pker, its own promoter, P43, the vegetative growth promoter, or the combination of P43-Pker into plasmid pUB18. Transformation of the protease-deficient strain B. subtilis DB104 with these plasmids generated transformant strains FDB-3, FDB-108 and FDB-29 respectively. All transformants expressed active keratinase in both feather and LB media, in contrast to PWD-1, in which kerA was repressed when grown in LB medium. With P43-Pker upstream of kerA, FDB-29 displayed the highest activity in feather medium. Production of keratinase in PWD-1 and transformants was further characterized when glucose or casamino acids were supplemented into the feather medium. These studies help understand the regulation of kerA expression and, in the long run, can help strain development and medium conditioning for the production of this industrially important keratinase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/sj.jim.2900440
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  • 3
    Electronic Resource
    Electronic Resource
    Metal interactions in algal toxicology: conventional versus in vivo tests (1981)
    Springer
    Hydrobiologia 85 (1981), S. 67-71 
    Details
    ISSN: 1573-5117
    Keywords: metal interactions ; toxicity ; algal assays ; bottle test ; algae ; Scenedesmus quadricauda
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Different studies on the toxicity of the same metals to algae have often shown divergent and sometimes contradictory results. The inconsistency of these findings was often attributed to environmental factors such as the degree of chelation, complexation and precipitation of metals. Conventionally, toxicity tests of metal mixtures were conducted by adding metals to algae growing in synthetic media. In our study, we examined the ‘in vivo’ toxic effects of metals by pretreating the algal cells with one metal, resuspendeding them in fresh medium, then exposing them to a second metal. The algal response showed marked differences between the conventional and the new approach. The conventional approach shows that the toxicity depends upon the complexes formed externally, whereas the in vivo approach shows that the toxicity probably depends upon the molecular transformation of the metals internally.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00011346
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    Paper (German National Licenses)
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