Public defence in Biotechnology, M.Sc. (Tech.) Sami Havukainen

Public defence from the Aalto University School of Chemical Engineering, Department of Bioproducts and Biosystems
Doctoral hat floating above a speaker's podium with a microphone

Title of the thesis: Sugar transport in Trichoderma reesei

Doctoral student: M.Sc. (Tech.) Sami Havukainen
Opponent: Professor Matthias G. Steiger, Vienna University of Technology, Austria
Custos: Professor Alexander Frey, Aalto University School of Chemical Engineering 

Sugar transport in Trichoderma reesei

Fungi are present in our everyday lives, although we rarely note their presence. Some fungal species are used in the biotechnology industry to produce food, pharmaceuticals, and many other products. One of the most important fungal production hosts in biotechnology industry is Trichoderma reesei, which is used to produce a wide variety of enzymes. It natively produces biomass-degrading enzymes, which can be used in biofuels production processes. These enzymes, and the improvement of their production, have been the subject of many studies. Less attention has been paid to understand how T. reesei obtains nutrients, such as the sugars released from the biomass by the aforementioned enzymes, from its environment. The transport of sugars across the cell membrane is mediated by specialized sugar transporter proteins. The genome of T. reesei has been predicted to code for numerous sugar transporters, although only few of them have been characterized in the literature. As the availability of sugars affects the production of biomass-degrading enzymes, manipulation of sugar transport processes could lead to improved enzyme production and thus reduce the costs of biofuels production.
The aim of this thesis was to characterize the most important members of T. reesei sugar transportome. Transporters were functionally characterized by heterologously expressing them in yeast Saccharomyces cerevisiae or in oocytes of the frog Xenopus laevis. We were able to characterize multiple T. reesei sugar transporters, including three which had not been described previously. Importantly, we could demonstrate transport function for CRT1, which has been shown to play a crucial role in the production of biomass-degrading enzymes. We were also able to further establish the X. laevis expression system as a powerful tool for studying fungal sugar transporters. Our results contain a lot of new information about T. reesei sugar transporters, and they can be used as the basis for many future studies.

Thesis available for public display 10 days prior to the defence 

Contact information:
M.Sc. (Tech.) Sami Havukainen
[email protected] 

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