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  • Enzyme  (1)
  • particulate organic carbon (POC)  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Tryptophanase from a marine bacterium, Vibrio K-7 synthesis, purification, and some chemical catalytic properties (1979)
    Springer
    Archives of microbiology 122 (1979), S. 169-175 
    Details
    ISSN: 1432-072X
    Keywords: Tryptophanase ; Vibrio ; Marine Vibrio ; Bacteria ; Enzyme ; Tryptophan ; Indole ; Amino acid ; Pyridoxal 5′-phosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The conditions for synthesis, purification, and properties of tryptophanase by a marine organism (Vibrio K-7) were studied. Tryptophanase was induced by tryptophan and its analogs, and partially repressed by 0.5% glucose or glycerol. NaCl (0.4M) was required for optimal growth and tryptophanase activity in whole cells. The enzyme was purified to 92% homogeneity by heat treatment, hydroxyapatite chromatography and fractionation with ammonium sulfate. This tryptophanase has been found to have kinetic properties similar to the tryptophanase from other microorganisms. It carries out both α, β-elimination reactions (using tryptophan, serine, cysteine and S-methyl-cysteine as substrates) and β-replacement reactions (forming tryptophan from indole and serine, cysteine or S-methyl-cysteine). The enzyme has a sedimentation coefficient of 9.2S and requires pyridoxal 5′-phosphate as a cofactor. The optimal pH for the tryptophanase reaction is pH 8.0.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00411356
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  • 2
    Electronic Resource
    Electronic Resource
    Relationships between bacterial productivity and organic carbon at a soil—stream interface (1998)
    Springer
    Hydrobiologia 386 (1998), S. 45-53 
    Details
    ISSN: 1573-5117
    Keywords: stream sediments ; riparian zone ; dissolved organic carbon (DOC) ; particulate organic carbon (POC) ; FAME yield ; bacterial productivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Microbial communities at soil-stream interfaces may be particularly important in regulating amounts and forms of nutrients that leave upland soils and enter stream ecosystems. While microbial communities are thought to be responsible for key nutrient transformations within near-stream sediments, there is relatively little mechanistic information on factors that control microbial activities in these areas. In this study, we examine the roles of dissolved organic carbon (DOC) vs. particulate organic carbon (POC) as potential controls on rates of bacterial productivity (measured as incorporation of [3H]thymidine into bacterial DNA) and amounts of bacterial biomass (measured as fatty acid yield) in sediments along a transect perpendicular to a soil–stream interface. We hypothesized that spatial patterns in bacterial productivity would vary in response to strong and persistent patterns in pore-water concentrations of DOC that were observed along a soil-stream transect throughout a 2-year period. Our results did not support the existence of such a link between pore-water DOC and bacterial productivity. In contrast, we found bacterial productivity and biomass were related to small-scale spatial variations in sediment POC on 3 of 4 sample dates. While our results indicate that total bacterial productivity in near-stream sediments is not consistently linked to spatial variations in pore-water DOC, it is likely that DOC and POC are not mutually exclusive and the relative contribution of DOC and POC to sedimentary microbes varies temporally and spatially in different riparian habitats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003583813445
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    Paper (German National Licenses)
    Fulltext
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