Defence of doctoral thesis: Monika Tõlgo – Discovery and applications of family AA9 lytic polysaccharide monooxygenases
Chalmers | WWSC
Opponent:Professor Maija Tenkanen, University of Helsinki, Finland
Supervisor: Professor Lisbeth Olsson, Chalmers
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To produce biofuels and biochemicals via fermentation, polysaccharides present in biomass must be first degraded into their constituent sugar units. This process is called saccharification and is achieved by enzymes, which are expensive bioreagents and therefore require optimization. Lytic polysaccharide monooxygenases (LPMOs) are enzymes that play a crucial role in saccharification. LPMOs are unique compared to other saccharifying enzymes as they use a different, oxidative mechanism. I have studied a specific type of LPMOs (AA9s), mainly from the fungus T. terrestris LPH172. I show that besides cellulose, some of these AA9s are highly active on xylan, another important component of wood biomass. In fact, my thesis describes how to increase AA9 activity on xylan even further. These findings will help to lower the cost of saccharification and broaden the range of usable LPMO substrates.
AA9s, supplied as part of enzyme cocktails, are currently being used in biorefineries to degrade biomass. I showed that one type of AA9 could increase, by up to 1.6-fold, the saccharification yields of mildly pretreated spruce, a notoriously hard-to-degrade but widely available biomass in Sweden. Separately, I showed that another AA9 could modify cellulose instead of degrading it. This is important as it allows the addition of new functions to sulfated nanocellulose and, hence, the production of novel and sustainable bio-based materials.