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  • 2000-2004  (3)
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Material
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Biodegradation of atrazine in sand sediments and in a sand-filter (2000)
    Springer
    Applied microbiology and biotechnology 54 (2000), S. 589-596 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The potential of a microbial consortium for treating waters contaminated with atrazine was considered. In conventional liquid culture, atrazine and its two dealkylated by-products were equally metabolised by the microbial consortium. Transient production of hydroxyatrazine was observed during atrazine catabolism, indicating that the catabolic pathway was similar to the one reported for isolates capable of atrazine mineralisation. This consortium was then inoculated to sediments sampled from an artificial recharge site. These sediments were contaminated by atrazine and diuron and exhibited only a slow endogenous herbicide dissipation. Inoculated microorganisms led to extensive atrazine degradation and survived for more than 10 weeks in the sediments. A rudimentary bioreactor was then setup using a soil core originating from the same recharge site. Degrading microorganisms rapidly colonised the core and expressed their degrading activity. The efficiency of the bioreactor was improved in the presence of spiked environmental surface waters. Atrazine degraders thus possibly benefited from the other organic sources in developing and expressing their activity. The microbial consortium did not initially exhibit the capacity to degrade diuron, which was used as reference compound. No change in this characteristic was detected throughout the study.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530000418
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Glutathione-mediated mineralization of 14C-labeled 2-amino-4,6-dinitrotoluene by manganese-dependent peroxidase H5 from the white-rot fungus Phanerochaete chrysosporium (2000)
    Springer
    Applied microbiology and biotechnology 54 (2000), S. 659-664 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Manganese-dependent peroxidase (MnP) H5 from the white-rot fungus Phanerochaete chrysosporium, in the presence of either Mn(II) (10 mM) or GSH (10 mM), was able to mineralize 14C-U-ring-labeled 2-amino-4,6-dinitrotoluene (2-A-4,6-DNT) up to 29% in 12 days. When both Mn(II) and GSH were present, the mineralization extent reached 82%. On the other hand, no significant mineralization was observed in the absence of both Mn(II) and GSH, suggesting the requirement of a mediator [either Mn(II) or GSH] for the degradation of 2-A-4,6-DNT by MnP. Using electron spin resonance (ESR) techniques, it was found that the glutathionyl free radical (GS•) was produced through the oxidation of GSH by MnP in the presence as well as in the absence of Mn(II). GS• was also generated through the direct oxidation of GSH by Mn(III). Our results strongly suggest the involvement of GS• in the GSH-mediated mineralization of 2-A-4,6-DNT by MnP.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530000436
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Modelling of continuous microbial cultivation taking into account the memory effects (2000)
    Springer
    Bioprocess engineering 22 (2000), S. 517-527 
    Details
    ISSN: 0178-515X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The problem of chemostat dynamics modelling for the purpose of control is considered. The “memory” of the culture is explicitly taken into account. Two possibilities for improving the quality of the proposed modelling approaches are discussed. A general model that accounts for the culture `memory' by means of different `memory' functions in the expressions of the specific growth rate and of the specific consumption rate and a polynomial function of the substrate concentration for the yield factor is proposed. The case where the maintenance energy is taken into account is also discussed. Two modifications of the general model (μ-type and S-type) are presented. A zero-order `memory' function and a δ-function with delay are applied in order to describe the `memory' effects. Continuous growth of the strain Saccharomyces cerevisiae on a glucose limited medium is considered as a case study. Detailed investigations of the variety of models, derived from the general model by applying different `memory' functions and different assumptions are carried out. The results are compared with those previously reported for the same process. It is shown that a significant improvement in predicting the substrate dynamics (not accompanied by any decrease in the quality of the model with respect to the biomass concentration) could be achieved, involving a first- or second-order polynomial function for the yield factor. It is also shown that the quality of the model mainly depends on the way that `memory' function is incorporated. The detailed investigations give priority to the μ-type models. In this case past values of both biomass and substrate variables are considered. The time delay models with pure (constant) delay and those which account for the culture `memory' by zero-order `memory' function (adaptability parameter) are compared with respect to their utilization for the purpose of model-based control.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004499900095
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    Paper (German National Licenses)
    Fulltext
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