umu.sePublikasjoner
Endre søk
Begrens søket
1 - 8 of 8
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1. Allas, Ular
    et al.
    Toom, Lauri
    Selyutina, Anastasia
    Maeorg, Uno
    Medina, Ricardo
    Merits, Andres
    Rinken, Ago
    Hauryliuk, Vasili
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS). University of Tartu, Institute of Technology, Nooruse 1, Tartu 50411, Estonia.
    Kaldalu, Niilo
    Tenson, Tanel
    Antibacterial activity of the nitrovinylfuran G1 (Furvina) and its conversion products2016Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, artikkel-id 36844Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    2-Bromo-5-(2-bromo-2-nitrovinyl) furan (G1 or Furvina) is an antimicrobial with a direct reactivity against thiol groups. It is active against Gram-positive and Gram-negative bacteria, yeasts and filamentous fungi. By reacting with thiol groups it causes direct damage to proteins but, as a result, is very short-living and interconverts into an array of reaction products. Our aim was to characterize thiol reactivity of G1 and its conversion products and establish how much of antimicrobial and cytotoxic effects are due to the primary activity of G1 and how much can be attributed to its reaction products. Stability of G1 in growth media as well as its conversion in the presence of thiols was characterized. The structures of G1 decomposition products were determined using NMR and mass-spectroscopy. Concentration-and time-dependent killing curves showed that G1 is bacteriostatic for Escherichia coli at the concentration of 16 mu g/ml and bactericidal at 32 mu g/ml. However, G1 is inefficient against non-growing E. coli. Addition of cysteine to medium reduces the antimicrobial potency of G1. Nevertheless, the reaction products of G1 and cysteine enabled prolonged antimicrobial action of the drug. Therefore, the activity of 2-bromo-5-(2-bromo-2-nitrovinyl) furan is a sum of its immediate reactivity and the antibacterial effects of the conversion products.

  • 2.
    Cavka, Adnan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Biorefining of lignocellulose: Detoxification of inhibitory hydrolysates and potential utilization of residual streams for production of enzymes2013Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Lignocellulosic biomass is a renewable resource that can be utilized for the production of biofuels, chemicals, and bio-based materials. Biochemical conversion of lignocellulose to advanced biofuels, such as cellulosic ethanol, is generally performed through microbial fermentation of sugars generated by thermochemical pretreatment of the biomass followed by an enzymatic hydrolysis of the cellulose. The aims of the research presented in this thesis were to address problems associated with pretreatment by-products that inhibit microbial and enzymatic biocatalysts, and to investigate the potential of utilizing residual streams from pulp mills and biorefineries to produce hydrolytic enzymes.

    A novel method to detoxify lignocellulosic hydrolysates to improve the fermentability was investigated in experiments with the yeast Saccharomyces cerevisiae. The method is based on treatment of lignocellulosic slurries and hydrolysates with reducing agents, such as sodium dithionite and sodium sulfite. The effects of treatment with sodium borohydride were also investigated. Treatment of a hydrolysate of Norway spruce by addition of 10 mM dithionite resulted in an increase of the balanced ethanol yield from 0.03 to 0.35 g/g. Similarly, the balanced ethanol yield of a hydrolysate of sugarcane bagasse increased from 0.06 to 0.28 g/g after treatment with 10 mM dithionite. In another study with a hydrolysate of Norway spruce, addition of 34 mM borohydride increased the balanced ethanol yield from 0.02 to 0.30 g/g, while the ethanol productivity increased from 0.05 to 0.57 g/(L×h). While treatment with sulfur oxyanions had a positive effect on microbial fermentation and enzymatic hydrolysis, treatment with borohydride resulted in an improvement only for the microbial fermentation. The chemical effects of treatments of hydrolysates with sodium dithionite, sodium sulfite, and sodium borohydride were investigated using liquid chromatography-mass spectrometry (LC-MS). Treatments with dithionite and sulfite were found to rapidly sulfonate inhibitors already at room temperature and at a pH that is compatible with enzymatic hydrolysis and microbial fermentation. Treatment with borohydride reduced inhibitory compounds, but the products were less hydrophilic than the products obtained in the reactions with the sulfur oxyanions.

    The potential of on-site enzyme production using low-value residual streams, such as stillage, was investigated utilizing recombinant Aspergillus niger producing xylanase and cellulase. A xylanase activity of 8,400 nkat/ml and a cellulase activity of 2,700 nkat/ml were reached using stillages from processes based on waste fiber sludge. The fungus consumed a large part of the xylose, the acetic acid, and the oligosaccharides that were left in the stillages after fermentation with S. cerevisiae. In another study, the capability of two filamentous fungi (A. niger and Trichoderma reesei) and three yeasts (S. cerevisiae, Pichia pastoris, and Yarrowia lipolytica) to grow on inhibitory lignocellulosic media were compared. The results indicate that the two filamentous fungi had the best capability to utilize different nutrients in the media, while the S. cerevisiae strain exhibited the best tolerance against the inhibitors. Utilization of different nutrients would be especially important in enzyme production using residual streams, while tolerance against inhibitors is desirable in a consolidated bio-process in which the fermenting microorganism also contributes by producing enzymes.

  • 3.
    Cavka, Adnan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Alriksson, Björn
    Processum Biorefinery Initiative AB, 891 22 Örnsköldsvik, Sweden.
    Rose, Shaunita H.
    Department of Microbiology, Stellenbosch University, Stellenbosch, 7602, South Africa.
    van Zyl, Willem H.
    Department of Microbiology, Stellenbosch University, Stellenbosch, 7602, South Africa.
    Jönsson, Leif J.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Production of cellulosic ethanol and enzyme from waste fiber sludge using SSF, recycling of hydrolytic enzymes and yeast, and recombinant cellulase-producing Aspergillus niger2014Inngår i: Journal of Industrial Microbiology & Biotechnology, ISSN 1367-5435, E-ISSN 1476-5535, Vol. 41, nr 8, s. 1191-1200Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bioethanol and enzymes were produced from fiber sludges through sequential microbial cultivations. After a first simultaneous saccharification and fermentation (SSF) with yeast, the bioethanol concentrations of sulfate and sulfite fiber sludges were 45.6 and 64.7 g/L, respectively. The second SSF, which included fresh fiber sludges and recycled yeast and enzymes from the first SSF, resulted in ethanol concentrations of 38.3 g/L for sulfate fiber sludge and 24.4 g/L for sulfite fiber sludge. Aspergillus niger carrying the endoglucanase-encoding Cel7B gene of Trichoderma reesei was grown in the spent fiber sludge hydrolysates. The cellulase activities obtained with spent hydrolysates of sulfate and sulfite fiber sludges were 2,700 and 2,900 nkat/mL, respectively. The high cellulase activities produced by using stillage and the significant ethanol concentrations produced in the second SSF suggest that onsite enzyme production and recycling of enzyme are realistic concepts that warrant further attention.

  • 4.
    Cavka, Adnan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Jönsson, Leif J.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Comparison of the growth of filamentous fungi and yeasts in lignocellulose-derived mediaManuskript (preprint) (Annet vitenskapelig)
  • 5.
    Harinikumar, K. M.
    et al.
    Department of Plant Biotechnology, University of Agricultural Sciences, G.K.V.K Campus. Bengaluru, India.
    Kudahettige-Nilsson, Rasika Lasanthi
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Devadas, A.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Holmgren, Marie
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Sellstedt, Anita
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Bioethanol production from four abundant Indian agricultural wastes2017Inngår i: Biofuels, ISSN 1759-7269, E-ISSN 1759-7277Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Lignocellulose feedstocks are promising second-generation sources of ethanol biofuel. They include massive amounts of agricultural waste generated in India, much of which is currently burnt (exacerbating major pollution problems), but could potentially be fermented. To assist efforts to realize this potential, four abundant kinds of Indian agricultural residues (sugarcane bagasse and straw from rice, sweet sorghum and millet) were hydrolyzed via a dilute-acid method and fermented at 27 °C, using the white-rot fungus Trametes versicolor as a biocatalyst. The total carbohydrate contents of the agriculture wastes were analyzed, as well as soluble sugar contents of the hydrolysates at the start and end of the fermentations; their ethanol yields and activities of the key enzymes aldehyde dehydrogenase and pyruvate decarboxylase were also measured. Results show that ca. 85–90% of the fermentable sugars were used for ethanol production, and the enzyme activities are consistent with the observed yields. The findings indicate a great potential for ethanol production from Indian agricultural waste.

  • 6.
    Jönsson, Leif J.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Alriksson, Björn
    Nilvebrant, Nils-Olof
    Bioconversion of lignocellulose: inhibitors and detoxification2013Inngår i: Biotechnology for Biofuels, ISSN 1754-6834, E-ISSN 1754-6834, Vol. 6, artikkel-id 16Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bioconversion of lignocellulose by microbial fermentation is typically preceded by an acidic thermochemical pretreatment step designed to facilitate enzymatic hydrolysis of cellulose. Substances formed during the pretreatment of the lignocellulosic feedstock inhibit enzymatic hydrolysis as well as microbial fermentation steps. This review focuses on inhibitors from lignocellulosic feedstocks and how conditioning of slurries and hydrolysates can be used to alleviate inhibition problems. Novel developments in the area include chemical in-situ detoxification by using reducing agents, and methods that improve the performance of both enzymatic and microbial biocatalysts.

  • 7. Kocík, Jaroslav
    et al.
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Bourajoini, Hasna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Pham, Tung Ngoc
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Faculty of Science and Engineering, Industrial Chemistry & Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Hájek, Martin
    Čapek, Libor
    Screening of active solid catalysts for esterification of tall oil fatty acids with methanol2017Inngår i: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 155, nr 1, s. 34-38Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The paper is focused on the description of the activity/selectivity of mesoporous silica based materials loaded with various types of active species in the esterification of tall oil free fatty acids. The metals such as aluminium, molybdenum, gallium and zinc, including their combinations were impregnated on the mesoporous silica, which was tested in esterification reaction. All these catalysts preserved its tall oil free fatty conversion in the first and the second catalytic cycles. However, while only insignificant amount of gallium or molybdenum was lost from the solid catalyst into the liquid phases, zinc leached from every studied solid catalyst. In contrast to impregnated gallium on mesoporous silica, which exhibited higher acidity and higher tall oil free fatty acids conversion in the first catalytic cycle, but its value was not preserved in the second catalytic test.

  • 8. Maciejewska, Barbara
    et al.
    Zrubek, Karol
    Espaillat, Akbar
    Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS). Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Wisniewska, Magdalena
    Rembacz, Krzysztof P.
    Cava, Felipe
    Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS). Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Dubin, Grzegorz
    Drulis-Kawa, Zuzanna
    Modular endolysin of Burkholderia AP3 phage has the largest lysozyme-like catalytic subunit discovered to date and no catalytic aspartate residue2017Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, artikkel-id 14501Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Endolysins are peptidoglycan-degrading enzymes utilized by bacteriophages to release the progeny from bacterial cells. The lytic properties of phage endolysins make them potential antibacterial agents for medical and industrial applications. Here, we present a comprehensive characterization of phage AP3 modular endolysin (AP3gp15) containing cell wall binding domain and an enzymatic domain (DUF3380 by BLASTP), both widespread and conservative. Our structural analysis demonstrates the low similarity of an enzymatic domain to known lysozymes and an unusual catalytic centre characterized by only a single glutamic acid residue and no aspartic acid. Thus, our findings suggest distinguishing a novel class of muralytic enzymes having the activity and catalytic centre organization of DUF3380. The lack of amino acid sequence homology between AP3gp15 and other known muralytic enzymes may reflect the evolutionary convergence of analogous glycosidases. Moreover, the broad antibacterial spectrum, lack of cytotoxic effect on human cells and the stability characteristics of AP3 endolysin advocate for its future application development.

1 - 8 of 8
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf