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71.
Interactions of bacteria and fungi on decomposing litter: differential extracellular enzyme activities 总被引:10,自引:0,他引:10
Fungi and bacteria are key agents in plant litter decomposition in freshwater ecosystems. However, the specific roles of these two groups and their interactions during the decomposition process are unclear. We compared the growth and patterns of degradative enzymes expressed by communities of bacteria and fungi grown separately and in coexistence on Phragmites leaves. The two groups displayed both synergistic and antagonistic interactions. Bacteria grew better together with fungi than alone. In addition, there was a negative effect of bacteria on fungi, which appeared to be caused by suppression of fungal growth and biomass accrual rather than specifically affecting enzyme activity. Fungi growing alone had a high capacity for the decomposition of plant polymers such as lignin, cellulose, and hemicellulose. In contrast, enzyme activities were in general low when bacteria grew alone, and the activity of key enzymes in the degradation of lignin and cellulose (phenol oxidase and cellobiohydrolase) was undetectable in the bacteria-only treatment. Still, biomass-specific activities of most enzymes were higher in bacteria than in fungi. The low total activity and growth of bacteria in the absence of fungi in spite of apparent high enzymatic efficiency during the degradation of many substrates suggest that fungi provide the bacteria with resources that the bacteria were not able to acquire on their own, most probably intermediate decomposition products released by fungi that could be used by bacteria. 相似文献
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Environmental Sensitivity Indices (ESI) composed of many field-data are essential for monitoring and control systems. At the
beginning of the last decade an ESI of the German Wadden Sea was developed for use by the relevant authorities. This ESI was
derived by experts semi-manually analysing the extensive field data-set.
An algorithm is presented here which emulates human expert-decisions on the classification of sensitivity classes. This will
permit the necessary regular updates of ESI-determination when new field data become available using automated classifications
procedures. After tuning the algorithm parameters it generates decisions identical to those of human experts in about 97%
of all locations tested. In addition, the algorithm presented also enables erroneous or extremely seldom field data to be
identified. 相似文献
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75.
The quality of Albanian natural waters and the human impact 总被引:6,自引:0,他引:6
Albania possesses a wealth of aquatic ecosystems, many of enormous natural and biological value, such as the Lakes Ohrid, Prespa and Shkodra, glacial lakes, river valleys, and coastal lagoons. Although many habitats are highly polluted by inorganic and organic wastes, detailed knowledge on the water quality is still lacking. For the first time, an environmental assessment of the water quality is presented and the main polluting sources identified. As a consequence, a systematic control and the establishment of routine monitoring of surface and groundwater is proposed, which elucidates the present environmental state and helps to develop new strategies of waste and wastewater management. It would help allow Albania to reach an international standard in environmental protection, as a part of UNECE Convention, the Mediterranean Action Plan, the MAP/UNEP Medpol Program and the Basel Convention. 相似文献
76.
Helmut Bruns 《Die Naturwissenschaften》1979,66(4):197-201
Numerous computer programs have gained entry into drug research; some of them are already used as a matter of routine, whereas others are still being tested. The special advantages of the use of computer programs are shown for the two fields “computer-assisted synthesis planning” and “quantitative structure-activity relationships”. Several aspects of cooperation between man and computer are briefly discussed. 相似文献
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79.
Helmut G. F. Winkler 《Die Naturwissenschaften》1954,41(24):574-575
80.