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- Peciulyte, Ausra, 1986, et al.
(författare)
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Critical redox processes during enzymatic saccharification of plant biomass: Lytic polysaccharide monooxygenases at play
- 2017
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Ingår i: Cellulases & Other carbohydrate-Active Enzymes, Gordon Research Conference.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The recent discovery of redox-active enzymes termed lytic polysaccharide monooxygenases (LPMOs) has led to a significant improvement in the efficiency of enzymatic hydrolysis and thus in the process of the production of biofuels. During saccharification of lignocellulose reactive oxygen species (•OH-; •O2-; H2O2) can be generated as an outcome of redox processes via enzymatic and non-enzymatic routes. These reactive oxygen species are toxic for the enzymes.In this project, redox processes of lignocellulosic biomass during enzymatic saccharification were investigated. A rapid decrease of pH was observed during lignocellulose incubation with and without enzymes which is an indication of redox reactions happening in the complex lignocellulosic material. We do not think that acetate release from hemicellulose alone could explain a decrease in pH values. Carbon dioxide release was observed in lignocellulose during incubation with and without enzymes. There was less carbon dioxide released in the enzyme mixtures where LPMO was present after two days of saccharification. Addition of catalase, which terminates chains of radical chemistry by the dismutation of H2O2 into water and O2, resulted in the improvement of enzymatic saccharification and reduction of acidifying reactions taking place.
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| 2. |
- Peciulyte, Ausra, 1986, et al.
(författare)
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Critical redox processes during enzymatic saccharification of plant biomass: Lytic polysaccharide monooxygenases at play
- 2017
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Ingår i: Science & Technology Day electronic book.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- s a result of the increasing burden on the environment and the scarcity of natural resources, we need to find new ways of supplying a growing population with products for daily life. In a bio-based economy we want to produce bioplastics, biochemicals and biofuels from plant biomass (lignocellulose). One of the reasons why lignocellulose is interesting is that it could serve as an energy source for microorganisms, which could be used to produce many different products of interest. However, the source of energy in lignocellulose is not readily available. We need to use certain enzymes, known collectively as cellulases, which are produced by other microorganisms, such as bacteria and filamentous fungi, to degrade lignocellulose into glucose, which can serve as an energy source.The recent discovery of enzymes termed lytic polysaccharide monooxygenases has led to a significant improvement in the efficiency of enzymatic hydrolysis and thus in the process of the production of biofuels. These enzymes are capable of breaking glycosidic bonds using oxidative mechanism which has not been known until recently.In this project I am focused on addressing how the application of these redox- active enzymes can reach its full potential. More specifically, I am investigating redox processes of lignocellulosic biomass during enzymatic saccharification. I combined electrochemistry (cyclic voltammetry), gas chromatography and high performance liquid chromatography techniques to investigate the saccharification of lignocellulose process.
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| 3. |
- Peciulyte, Ausra, 1986, et al.
(författare)
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Redox processes acidify and decarboxylate steam-pretreated lignocellulosic biomass and are modulated by LPMO and catalase
- 2018
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Ingår i: Biotechnology for Biofuels. - : Springer Science and Business Media LLC. - 1754-6834 .- 1754-6834. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: The bioconversion of lignocellulosic feedstocks to ethanol is being commercialised, but further process development is required to improve their economic feasibility. Efficient saccharification of lignocellulose to fermentable sugars requires oxidative cleavage of glycosidic linkages by lytic polysaccharide monooxygenases (LPMOs). However, a proper understanding of the catalytic mechanism of this enzyme class and the interaction with other redox processes associated with the saccharification of lignocellulose is still lacking. The in-use stability of LPMO-containing enzyme cocktails is increased by the addition of catalase implying that hydrogen peroxide (H2O2) is generated in the slurry during incubation. Therefore, we sought to characterize the effects of enzymatic and abiotic sources of H2O2on lignocellulose hydrolysis to identify parameters that could improve this process. Moreover, we studied the abiotic redox reactions of steam-pretreated wheat straw as a function of temperature and dry-matter (DM) content. Results: Abiotic reactions in pretreated wheat straw consume oxygen, release carbon dioxide (CO2) to the slurry, and decrease the pH. The magnitude of these reactions increased with temperature and with DM content. The presence of LPMO during saccharification reduced the amount of CO2liberated, while the effect on pH was insignificant. Catalase led to increased decarboxylation through an unknown mechanism. Both in situ-generated and added H2O2caused a decrease in pH. Conclusions: Abiotic redox processes similar to those that occur in natural water-logged environments also affect the saccharification of pretreated lignocellulose. Heating of the lignocellulosic material and adjustment of pH trigger rapid oxygen consumption and acidification of the slurry. In industrial settings, it will be of utmost importance to control these processes. LPMOs interact with the surrounding redox compounds and redirect abiotic electron flow from decarboxylating reactions to fuel the oxidative cleavage of glycosidic bonds in cellulose.
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| 4. |
- Snaebjörnsson, Thorkell, 1982, et al.
(författare)
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Graft Diameter and Graft Type as Predictors of Anterior Cruciate Ligament Revision: A Cohort Study Including 18,425 Patients from the Swedish and Norwegian National Knee Ligament Registries
- 2019
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Ingår i: The Journal of bone and joint surgery. American volume. - 1535-1386. ; 101:20, s. 1812-1820
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: It is important to investigate and compare graft diameters as well as graft types to identify risk factors for revision after an anterior cruciate ligament (ACL) reconstruction. We performed the current study in order to analyze the early ACL revision rate among patients treated with hamstring tendon (HT) autografts or patellar tendon (PT) autografts of different diameters. Our hypothesis was that an increase in both HT and PT autograft diameters would reduce the risk of early ACL revision. METHODS: This retrospective study was based on prospectively collected data from the national knee ligament registries of Norway and Sweden and included patients who underwent primary ACL reconstruction during the period of 2004 through 2014. The primary end point was the 2-year incidence of ACL revision. The impact of graft type and diameter on the incidence of revision surgery was reported as relative risks (RRs) with 95% confidence intervals (CIs), estimated by using generalized linear models with a binomial distribution and log-link function. RESULTS: Of 58,692 patients identified, a total of 18,425 patients were included in this study. The 2-year rate of ACL revision was 2.10% (PT autografts, 2.63%; HT autografts, 2.08%; RR = 0.93 [95% CI = 0.60 to 1.45]). There was an increased risk of ACL revision among patients treated with HT autografts with a diameter of <8 mm compared with larger HT autografts (RR = 1.25 [95% CI = 1.01 to 1.57]). Patients treated with HT autografts with a diameter of ≥9.0 mm or ≥10.0 mm had a reduced risk of early ACL revision compared with patients treated with PT autografts. CONCLUSIONS: Patients treated with larger-diameter HT autografts had a lower risk of early ACL revision compared with those treated with HT autografts of <8 mm. Patients treated with HT autografts of ≥9 or ≥10 mm had a reduced risk of early ACL revision compared with patients treated with PT autografts. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.
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