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Charakterisierung bioaktiver Fischerelline in benthischen Cyanobakterien der Gattung Fischerella

Charakterisierung bioaktiver Fischerelline in benthischen Cyanobakterien der Gattung Fischerella

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Prüfsumme: MD5:5ec17b2fd0953e7c5261447d15596f20

GREILINGER DORIS, , 2002. Charakterisierung bioaktiver Fischerelline in benthischen Cyanobakterien der Gattung Fischerella [Master thesis]

@mastersthesis{GreilingerDoris2002Chara-7707, title={Charakterisierung bioaktiver Fischerelline in benthischen Cyanobakterien der Gattung Fischerella}, year={2002}, author={Greilinger Doris} }

application/pdf Charakterisierung bioaktiver Fischerelline in benthischen Cyanobakterien der Gattung Fischerella deu 2011-03-24T17:36:31Z Greilinger Doris Characterization of bioactive fischerellins in the cyanobacterium fischerella spp. deposit-license 2002 The benthic, nitrogen-fixing cyanobacterium Fischerella spp. produces at least two bioactive substances called fischerellins. Both fischerellins, fischerellin A and B, show allelopathic action against other cyanobacteria and green algae. Previous observations existed about additional yet unidentified fischerellins in Fischerella spp..<br />Aim of the first part of this study was to isolate and characterize additional fischerellins.<br />In order to do this the isolation as well as the detection procedure of fischerellins had to be improved first. The detection by HPLC was amended by using Reversed-Phase-C18-separation. The removal of pigments disturbing the detection of fischerellins was achived by preseparating the methanolic crude extracts of Fischerella spp. over normal-phase-solid-phase extraction. Resulting from the improved analytical method a new fischerellin, named fischerellin C, could be isolated and its structure partly characterized. Fischerellin C exhibits a chromophore similar to the known fischerellins with typical absorption maxima in methanol at 263, 277, 295, 313 nm. The molecular weight determined by mass spectrometry is 297 m/z. Although very similar in its structure to fischerellin A and B, fischerellin C shows no allelopathic activity in agar diffusion tests against Anabaena sp. PCC 7120. Beside the new fischerellin C other fischerellins matching the UV/Vis absorption spectra of fischerellin A and B were observed at different retention times. This indicates either other substituted fischerellins or additional isomers.<br />The second question addressed was how production of fischerellins is influenced by external conditions. In this study following abiotic conditions concerning media composition were varied. F. muscicola was cultured under nitrate or phosphate limitation. Further, different molybdenum and iron availability was tested on fischerellin production. However in none of the conducted experiments the fischerellin content nor the composition of different fischerellins showed clear dependance on varied concentrations. The variability in fischerellin content was even high in the same concentration levels. Despite often less biomass production with one exception no increased levels in fischerellins were found. Generally less fischerellins were found in the strongest iron and nitrogen limited cultures. This was interpreted as a result of the general impaired cell conditions seen by strongly decreased pigment content and less produced biomass. Although no dependance of fischerellin production on tested factors was found in this study influence of external factors on fischerellin production cannot be excluded. Greilinger Doris 2011-03-24T17:36:31Z

Dateiabrufe seit 01.10.2014 (Informationen über die Zugriffsstatistik)

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