Väitös (biokemia): MSc Asmaa Abbas
Aika
11.10.2024 klo 12.00 - 16.00
MSc Asmaa Abbas esittää väitöskirjansa ”Monitoring, suppression and molecular regulation mechanisms of mycotoxin-producing fungi” julkisesti tarkastettavaksi Turun yliopistossa perjantaina 11.10.2024 klo 12.00 (Turun yliopisto, Natura, luentosali X, Turku).
Vastaväittäjänä toimii dosentti Taina Lundell (Helsingin yliopisto) ja kustoksena professori Mikko Metsä-Ketelä (Turun yliopisto). Tilaisuus on englanninkielinen. Väitöksen alana on biokemia.
Väitöskirja yliopiston julkaisuarkistossa: https://urn.fi/URN:ISBN:978-951-29-9887-6
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Tiivistelmä väitöstutkimuksesta:
Aflatoxin B1 (AFB1) is a toxic secondary metabolite produced by Aspergillus fungi. This toxin can reach human through the consumption of contaminated food, leading to aflatoxicosis, which may cause liver cancer. Billions of people worldwide are exposed to aflatoxins (AFs) through their diet.
In my PhD, we developed a polyphasic approach to distinguish between aflatoxigenic and non-aflatoxigenic Aspergillus strains. This approach integrated data from phylogenetic, sequence, and toxin analyses to identify genetic diversity among Aspergillus isolates. We also developed a noncompetitive immunoassay for AFB1 detection in food. The single-step assay is performed in 15 min and has a detection limit of 70 pg/mL. The aflatoxin biosynthesis pathway consists of 30 genes and two specific regulators AflR and AflS. Our findings revealed that AflR and AflS directly interact forming a protein complex. AflS was found to moderately reduce the binding affinity of AflR to its target DNA site.
To eliminate AFs, we applied a methanolic extract from the Zanthoxylum bungeanum (Z. bungeanum) plant to Aspergillus fungi. The extract suppressed the AFB1 biosynthesis pathway in A. flavus. Interestingly, the suppression was mediated by the global regulators of secondary metabolism and cell development, including the velvet complex, rather than the pathway specific regulators (AflR and AflS). Moreover, co-inoculating the extract with Fusarium graminearum fungi effectively inhibited the fungal growth and deoxynivalenol (DON) production in both laboratory and field conditions.
Taken together, these findings highlight the importance of distinguishing between aflatoxin and non-aflatoxin producing fungi, as well as elucidating the molecular interactions between the master regulators AflR, AflS, and their DNA binding activities. Additionally, the findings suggest that Z. bungeanum extracts may facilitate the development of effective strategies to control AFB1 and DON contaminations.
Vastaväittäjänä toimii dosentti Taina Lundell (Helsingin yliopisto) ja kustoksena professori Mikko Metsä-Ketelä (Turun yliopisto). Tilaisuus on englanninkielinen. Väitöksen alana on biokemia.
Väitöskirja yliopiston julkaisuarkistossa: https://urn.fi/URN:ISBN:978-951-29-9887-6
***
Tiivistelmä väitöstutkimuksesta:
Aflatoxin B1 (AFB1) is a toxic secondary metabolite produced by Aspergillus fungi. This toxin can reach human through the consumption of contaminated food, leading to aflatoxicosis, which may cause liver cancer. Billions of people worldwide are exposed to aflatoxins (AFs) through their diet.
In my PhD, we developed a polyphasic approach to distinguish between aflatoxigenic and non-aflatoxigenic Aspergillus strains. This approach integrated data from phylogenetic, sequence, and toxin analyses to identify genetic diversity among Aspergillus isolates. We also developed a noncompetitive immunoassay for AFB1 detection in food. The single-step assay is performed in 15 min and has a detection limit of 70 pg/mL. The aflatoxin biosynthesis pathway consists of 30 genes and two specific regulators AflR and AflS. Our findings revealed that AflR and AflS directly interact forming a protein complex. AflS was found to moderately reduce the binding affinity of AflR to its target DNA site.
To eliminate AFs, we applied a methanolic extract from the Zanthoxylum bungeanum (Z. bungeanum) plant to Aspergillus fungi. The extract suppressed the AFB1 biosynthesis pathway in A. flavus. Interestingly, the suppression was mediated by the global regulators of secondary metabolism and cell development, including the velvet complex, rather than the pathway specific regulators (AflR and AflS). Moreover, co-inoculating the extract with Fusarium graminearum fungi effectively inhibited the fungal growth and deoxynivalenol (DON) production in both laboratory and field conditions.
Taken together, these findings highlight the importance of distinguishing between aflatoxin and non-aflatoxin producing fungi, as well as elucidating the molecular interactions between the master regulators AflR, AflS, and their DNA binding activities. Additionally, the findings suggest that Z. bungeanum extracts may facilitate the development of effective strategies to control AFB1 and DON contaminations.
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