228 research outputs found

    Enzymatic biomass utilization and modification

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    Environmental concerns, the requirements for energy and carbon efficiency as well as the need to reduce dependency on fossil feedstocks lead to a necessity to develop new bio-based processes and products that support sustainable development and create novel possibilities to boost Bioeconomy. Lignocellulosic biomass mainly composed of cellulose, hemicellulose and lignin is a renewable, abundant non-food starting material for various applications. Cellulases and related enzymes have for decades attracted substantial interest in various industrial applications. For the total hydrolysis of biomass to produce biofuels and other chemicals, mixtures of different (hemi)cellulolytic enzymes have been used, composed of cellobiohydrolases, endoglucanases, β-glucosidases, hemicellulases and helper activities that act in a synergistic manner. On the other hand, for the fibre-based applications usually tailored, or monocomponent enzyme preparations have been applied. The exact composition and proportions of the different enzymes depends in each case on the raw material used, and also on the biorefinery concept to be applied. Despite of the vast development of the lignocellulolytic enzymes, more efficient enzymes and enzyme cocktails are still needed. At VTT, novel cellulolytic enzymes have been discovered from environmental samples, culture collections, metagenomic libraries and genomic databases. Enzyme properties have also been improved by protein engineering. We have also analyzed the limiting factors in the hydrolysis, especially the role of hemicellulose and lignin. Molecular level mechanistic studies have paved way for development of more efficient enzymes. Besides biomass degradation, enzymes have been applied for fibre modification. Furthermore, protease deletion strains and strains with modified cellulase regulation pathways have made it possible to substantially increase protein production in Trichoderma reesei, the industrial production host. References: Igarashi K., Uchihashi, T., Koivula A., Wada, M., Kimura, S., Okamoto, T., Penttilä M., Ando, T. and Samejima, M. (2011) Traffic jams reduce hydrolytic efficiency of cellulase on cellulose surface. Science, 33, 1279-1282. Ilmén M., den Haan R, Brevnova E, McBride J, Wiswall E, Froehlich A, Koivula A, Voutilainen S.P, Siika-aho M, la Grange D.C., Thorngren N, Ahlgren S, Mellon M, Deleault K, Rajgarhia V, van Zyl W.H, Penttilä M (2011) High level secretion of cellobiohydrolases in Saccharomyces cerevisiae. Biotechnology for Biofuels 4, 30-45. Viikari, L., Vehmaanperä, J. and Koivula, A (2012) Lignocellulosic ethanol: from science to industry. Biomass and Bioenergy 46, 13-24. Nakamura, A., Tsukada, T., Auer,S., Furuta, T., Wada, M., Koivula,A., Igarashi, K., and Samejima M. (2013) Tryptophan residue at active-site tunnel entrance of Trichoderma reesei cellobiohydrolase Cel7A is important to initiate degradation of crystalline cellulose. J.Biol.Chem. 288, 13503-13510. Rahikainen, J. L., Moilanen, U., Nurmi-Rantala, S., Lappas, A., Koivula, A., Viikari, L., & Kruus, K. (2013). Effect of temperature on lignin-derived inhibition studied with three structurally different cellobiohydrolases. Bioresource Technology, 146, 118–25. Voutilainen S.P., Nurmi-Rantala, S., Penttilä M., and Koivula A. (2013) Engineering chimeric thermostable GH7 cellobiohydrolases in Saccharomyces cerevisiae. Appl. Microbiol. Biotechnol. 98, 2991-3001. Colabardini, A.C., Valkonen M; Huuskonen A; Siika-aho M; Koivula A; Goldman G.H; Saloheimo M (2016) Expression of two novel β-glucosidases from Chaetomium atrobrunneum in Trichoderma reesei and characterization of the heterologous protein products. Mol. Biotechnology. 58, 821-831

    Inhibitory effect of lignin on the hydrolysis of xylan by thermophilic and thermolabile GH11 xylanases

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    BACKGROUND: Enzymatic hydrolysis of lignocellulosic biomass into platform sugars can be enhanced by the addition of accessory enzymes, such as xylanases. Lignin from steam pretreated biomasses is known to inhibit enzymes by non-productively binding enzymes and limiting access to cellulose. The effect of enzymatically isolated lignin on the hydrolysis of xylan by four glycoside hydrolase (GH) family 11 xylanases was studied. Two xylanases from the mesophilic Trichoderma reesei, TrXyn1, TrXyn2, and two forms of a thermostable metagenomic xylanase Xyl40 were compared. RESULTS: Lignin isolated from steam pretreated spruce decreased the hydrolysis yields of xylan for all the xylanases at 40 and 50 °C. At elevated hydrolysis temperature of 50 °C, the least thermostable xylanase TrXyn1 was most inhibited by lignin and the most thermostable xylanase, the catalytic domain (CD) of Xyl40, was least inhibited by lignin. Enzyme activity and binding to lignin were studied after incubation of the xylanases with lignin for up to 24 h at 40 °C. All the studied xylanases bound to lignin, but the thermostable xylanases retained 22–39% of activity on the lignin surface for 24 h, whereas the mesophilic T. reesei xylanases become inactive. Removing of N-glycans from the catalytic domain of Xyl40 increased lignin inhibition in hydrolysis of xylan when compared to the glycosylated form. By comparing the 3D structures of these xylanases, features contributing to the increased thermal stability of Xyl40 were identified. CONCLUSIONS: High thermal stability of xylanases Xyl40 and Xyl40-CD enabled the enzymes to remain partially active on the lignin surface. N-glycosylation of the catalytic domain of Xyl40 increased the lignin tolerance of the enzyme. Thermostability of Xyl40 was most likely contributed by a disulphide bond and salt bridge in the N-terminal and α-helix regions. GRAPHICAL ABSTRACT: [Image: see text] SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13068-022-02148-4

    Eksperttiopettajan kielikasvatuksen käyttöteoria monikielisten lasten varhaiskasvatuksessa

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    In this case study we examine the practical theory of an expert teacher implementing bilingual pedagogy (Finnish-Swedish) in early childhood education with multilingual children. Practical theory refers to the pedagogical vision that guides a teacher’s actions and the focus of this study is the expert teacher’s practical theory regarding the use of different languages. The two research questions address the key aspects of the teacher’s practical theory and how these aspects related to the different languages. The dataset from two interviews with the expert teacher were thematically analyzed. The findings show that the teacher’s practical theory is constructed from a core value (equality of languages) and various aims and principles (e.g., mutual learning, supporting language-identities and pedagogical tact) that were closely intertwined. The findings suggest that in the expert teacher’s use of Finnish and Swedish the intent was to expand the children’s language resources whereas in the use of the children’s home language the purpose was to acknowledge and utilize their languages while creating language appreciation.Tässä tapaustutkimuksessa tarkastelemme, millainen käyttöteoria kaksikielistä pedagogiikkaa (suomi-ruotsi) varhaiskasvatuksessa toteuttavalla eksperttiopettajalla on eri kielten käytöstä monikielisten lasten kanssa toimiessa. Käyttöteorialla tarkoitetaan tässä pedagogista näkemystä, joka ohjaa opettajan toimintaa. Käyttöteoriaa eri kielten käytöstä lähestyttiin kahden tutkimuskysymyksen kautta, joissa tarkasteltiin kielikasvatuksen käyttöteorian keskeisiä osa-alueita ja niiden ilmenemistä eri kielissä. Aineistona oli yhden eksperttiopettajan kaksi haastattelua, jotka analysoitiin laadullisella temaattisella analyysillä. Tulokset osoittavat, että opettajan kielikasvatuksen käyttöteoriassa korostui yksi arvo (kielten yhtäläinen arvo) sekä useat tavoitteet ja periaatteet (esim. vastavuoroinen oppiminen, kieli-identiteetin tukeminen ja pedagoginen tahdikkuus), jotka olivat tiiviisti yhteydessä toisiinsa. Tulosten perusteella suomen ja ruotsin käytössä opettajan pyrkimyksenä oli kasvattaa monikielisten lasten kielellisiä resursseja. Lasten kotikielten käytöllä opettaja puolestaan tähtäsi ensisijaisesti lasten olemassa olevien kieliresurssien huomiointiin, hyödyntämiseen ja arvostukseen

    Life Satisfaction and Online-Gambling Communities : A Cross-National Study of Gambling Activities Among Young Finnish, American, South Korean and Spanish People

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    Publisher Copyright: © 2021, The Author(s).Gambling is a potential hazard to life satisfaction, yet peer relationships online might buffer this risk. This study analyzed the ways problem gambling is associated with life satisfaction as well as the extent to which the use of online-gambling community participation and, alternatively, offline belonging affect this association. A web-based survey was conducted among people aged 15–25 in Finland (n = 1,200), the United States (n = 1,212), South Korea (n = 1,192), and Spain (n = 1,212). The main variables included life satisfaction, problem gambling measured by the South Oaks Gambling Screen, online-gambling community participation, and offline belonging. Controls included compulsive internet use, hazardous drinking, psychological distress, income, age, and gender. Linear regression models were employed with country interactions. Results showed problem gambling had a negative relationship with life satisfaction, but the association was explained by control variables. Online-gambling community participation had a positive relationship with life satisfaction, especially among pathological gamblers who had poor offline relationships. Country comparisons revealed that the direct effect of excessive gambling and the compensating effect of online-gambling communities were most prominent in Finland.Peer reviewe

    Social Ecological Model of Problem Gambling: A Cross-National Survey Study of Young People in the United States, South Korea, Spain, and Finland

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    Problem gambling among young people is an emerging trend globally. The online environment in particular offers various possibilities for gambling engagement. This is the first cross-national survey study using the social ecological model to analyze problem gambling, especially in the online context. The study aimed to analyze how different social ecological spheres explain problem gambling. Participants were young people aged 15–25 in the United States (n = 1212), South Korea (n = 1192), Spain (n = 1212), and Finland (n = 1200). The South Oaks Gambling Screen (SOGS) instrument measured problem gambling. The regression models analyzed problem gambling with measures of intrapersonal, interpersonal, organizational, and societal spheres. Spanish participants had the highest SOGS score for problem gambling. In all countries, the variations in problem gambling were best explained by the organizational sphere measures (26%) when compared to the intrapersonal (11%), interpersonal (5%), and societal (3%) spheres. In the full model, the organizational sphere measures had strong associations with problem gambling. These included consumer debt, online gambling community participation, online casino participation, and exposure to online pop-up advertisements. Problem gambling was also associated with conformity to group norms in the interpersonal sphere, and male gender and impulsivity in the intrapersonal sphere. Cross-national results were similar in different countries. Within the final model, gambling community participation had the strongest association with problem gambling (β = 0.23, p < 0.001). The online context plays a major role in problem gambling behavior. The social ecological model is a useful tool for tackling problem gambling and developing preventative measures

    Online Relationships and Social Media Interaction in Youth Problem Gambling: A Four-Country Study

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    The objective of this study was to examine if belonging to online communities and social media identity bubbles predict youth problem gambling. An online survey was administered to 15–25-year-old participants in the United States (N = 1212), South Korea (N = 1192), Spain (N = 1212), and Finland (N = 1200). The survey measured two dimensions of online behavior: perceived sense of belonging to an online community and involvement in social media identity bubbles. Belonging to an online community was examined with a single item and involvement in social media identity bubbles was measured with the six-item Identity Bubble Reinforcement Scale. The South Oaks Gambling Screen was used to assess problem gambling. Statistical analyses utilized linear regression modeling. According to the analyses, strong sense of belonging to an online community was associated with higher problem gambling, but the association was observed mainly among those young individuals who were also involved in social media identity bubbles. For those youths who did not indicate identity bubble involvement, online relationships appeared to function as those offline. Some differences across the four countries were observed but overall, the results indicate that social media identity bubbles could partly explain the harmful influence that some online relations have on youth behavior
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