Chemische Charakterisierung und Spurenanalytik
Filtern
Dokumenttyp
- Vortrag (3)
Sprache
- Englisch (3)
Referierte Publikation
- nein (3)
Schlagworte
- Mycotoxins (3) (entfernen)
Organisationseinheit der BAM
- 1 Analytische Chemie; Referenzmaterialien (3) (entfernen)
Eingeladener Vortrag
- nein (3) (entfernen)
Mycotoxigenic fungal pathogens Fusarium and Alternaria are a leading cause of loss in cereal production. On wheat-ears, they are confronted by bacterial antagonists such as pseudomonads.
Studies on these groups’ interactions often neglect the infection process’s temporal aspects and the associated priority effects. In the present study, the focus was on how the first colonizer affects the subsequent ones. In a climate chamber experiment, wheat-ears were successively inoculated with two different strains (Alternaria tenuissima At625, Fusarium graminearum Fg23, or Pseudomonas simiae Ps9).
Over three weeks, microbial abundances and mycotoxin concentrations were analyzed and visualized via Self Organizing Maps with Sammon Mapping (SOM-SM). All three strains revealed different characteristics and strategies to deal with co-inoculation: Fg23, as the first colonizer, suppressed the establishment of At625 and Ps9. Nevertheless, primary inoculation of At625 reduced all of the Fusarium toxins and stopped Ps9 from establishing. Ps9 showed priority effects in delaying and blocking the production of the fungal mycotoxins. The SOM-SM analysis visualized the competitive strengths: Fg23 ranked first, At625 second, Ps9 third. Our findings of species-specific priority effects in a natural environment and the role of the mycotoxins involved are relevant for developing biocontrol strategies.
Ergot alkaloids play a significant role in human history for more than 1000 years and are part of the most common contaminants of food and feed worldwide. Their high toxicity against humans and livestock even at low concentrations causes a high demand for quick and reliable analytics even though no European limits for ergot alkaloids have been determined yet. Currently the most common methods for the quantitation of the six major ergot alkaloids and their corresponding stereoisomers are HPLC based, using either fluorescence or mass spectrometric detection. Whereas these conventional detection methods measure each compound individually, a novel approach is to transfer all ergot alkaloids to one basic structure, which could be measured as a sum parameter.
Since all ergots contain a lysergic acid amide moiety and a differing peptide component, cleaving the molecule into a simple lysergic acid derivative, which could be quantified via either HPLC-FLD or MS/MS, is intended. To clean up the cleavage reaction mixture molecularly imprinted polymers (MIPs) are a simple and effective way to separate the desired structure. Due to the selectivity of MIPs, an improved matrix separation is expected, which results in fewer interferences in the FLD and the possibility to measure samples with more complex matrices. When fully developed, the novel method could overcome some major drawbacks of the conventional detection methods. Higher throughput and the need for less well-trained personnel are just two advantages, that should lead to a quick and cheap quantitation of ergot alkaloids. First results of this project will be presented, funded by the German ZIM program (Zentrales Innovationsprogramm Mittelstand) of the Federal Ministry for Economic Affairs and Energy.
To keep up with emerging mycotoxins and their transformation products fast and reliable toxicity tests are needed. Toxicity testing of mycotoxins is carried out usually by performing in vitro assays or is evaluated by using laboratory animals like mice, rats or chicken in in vivo studies.
Settled between classical in vitro approaches and in vivo studies with higher animals are tests with the nematode Caenorhabditis elegans. Since Sydney Brenner described 1974 the cultivation and handling of C. elegans, this worm is widely used as model organism in developmental biology and neurology. Due to many benefits like easy and cheap cultivation, a completely sequenced genome and short generation time, it also plays an important role in toxicological research. Finally, the high number of conserved genes between human and C. elegans make the worm an ideal candidate for toxicological investigations.
In this study we used C. elegans to assess the toxic effects of the relevant food mycotoxin citrinin (CIT), the mycoestrogen zearalenone (ZEN) and the modified mycotoxin ZEN-14-sulfate (ZEN-14-S) on different lifetable parameters including reproduction, thermal and oxidative stress tolerance and lifespan. All tested mycotoxins significantly decreased the amount of offspring. In case of ZEN and CIT also significant negative effects on stress tolerance and lifespan were observed compared to the control group.
Moreover, metabolization of mycotoxins in the worms was investigated by using LC MS/MS. Extraction of the worms treated 5 days with mycotoxin-containing and UVC-killed bacteria showed metabolization of ZEN to α-ZEL and β-ZEL (ZEL = zearalenol, ratio about 3:2). ZEN 14-S was reduced to ZEL 14-S and CIT was metabolized to mono hydroxylated CIT.