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| 2. |
- Karlsson, Eva Nordberg, et al.
(författare)
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Cloning and sequence of a thermostable multidomain xylanase from the bacterium Rhodothermus marinus
- 1997
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Ingår i: Biochimica et Biophysica Acta - Gene Structure and Expression. - 0167-4781. ; 1353:2, s. 118-124
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Tidskriftsartikel (refereegranskat)abstract
- The gene (xyn1) encoding a Rhodothermus marinus xylanase has been cloned and expressed in Escherichia coli. The gene comprises 5 different domains in an unusual combination. The cellulose binding domains (CBDs) encoded by xyn1 are repeated in tandem at the N-terminus and show similarity with the CBD family IV. The xyn1-gene is the first example encoding a CBD family IV in combination with a xylan hydrolyzing catalytic domain of the glycosyl hydrolase family 10.
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| 3. |
- Karlsson, Eva Nordberg, et al.
(författare)
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Enzymatic specificity and hydrolysis pattern of the catalytic domain of the xylanase Xyn1 from Rhodothermus marinus
- 1998
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Ingår i: Journal of Biotechnology. - 0168-1656. ; 60:1-2, s. 23-25
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Tidskriftsartikel (refereegranskat)abstract
- The catalytic domain of a xylanase from Rhodothermus marinus was produced in Escherichia coli. The catalytic domain belongs to glycosyl hydrolase family 10. The produced protein has a 22-amino acid leader peptide followed by a 411-amino acid truncated xylanase. The molecular mass was 48 kDa and the recombinant xylanase had a pI of 4.9. The pH and temperature optima for activity were determined to be 7.5 and 80°C, respectively. At that temperature the enzyme had a half-life of 1 h 40 min. An addition of 1 mM calcium stabilized the activity of the enzyme at 80°C. The xylanase had its highest specific activity on oat spelt xylan but was active also on other xylans and to a limited extent on some other polysaccharides (soluble glucans). No exo- or endo-cellulase activity was observed. Hydrolysis of xylo-oligomers and oat spelt xylan was studied and the predominant products of hydrolysis were xylobiose and xylotriose. The enzyme was inactive on xylobiose, xylotriose and on the soluble fraction from oat spelt xylan. The R. marinus xylanase is shown to have a strong preference for internal linkages and is therefore classified as an endo-xylanase. Copyright (C) 1998 Elsevier Science B.V.
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| 5. |
- Nordberg Karlsson, Eva, et al.
(författare)
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Efficient production of truncated thermostable xylanases from Rhodothermus marinus in Escherichia coli fed-batch cultures
- 1999
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Ingår i: Journal of Bioscience and Bioengineering. - 1389-1723. ; 87:5, s. 598-606
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Tidskriftsartikel (refereegranskat)abstract
- A cultivation strategy for the production of two truncated thermostable recombinant xylanases (Xyn1ΔN and Xyn1ΔNC) was developed. Fed-batch cultivations of Escherichia coli strain BL21(DE3) with a controlled exponential glucose feed led to high specific production of the recombinant proteins. Addition of complex nutrients (e.g. Tryptone Soya Broth (TSB)) to the media were shown to increase both the specific growth rate during the production phase and the production per cell. The final cellmass concentration depended on the time of induction in relation to both the feed- start and the expected time at which the cultivation had to be terminated due to oxygen transfer limitations or cell lysis. The gene used for the genetic constructions (encoding Xyn1ΔN and Xyn1ΔNC) was originally isolated from Rhodothermus marinus. Recombinant protein expression was controlled by the T7 lac-promoter and induced in the fed-batch phase at low glucose concentrations by the single addition of either lactose or isopropyl-thio-β-D-galactoside (IPTG). In lactose-induced cells, the production of recombinant xylanase was delayed for approximately 30 min in comparison with those induced with IPTG, but the specific product levels were comparable at 3 h after induction. At this time, approximately 35% of the intracellular protein content was constituted by recombinant xylanase. Under the cultivation conditions used, production of the shorter deletion derivative (Xyn1ΔNC) led to nonspecific leakage and cell lysis, starting 1.5 or 2 h after induction with IPTG or lactose, respectively. At 3 h after induction, 50% of the produced protein (Xyn1ΔNC) was found in the culture medium. This was not the case for the longer protein (Xyn1ΔN), where only 10% of the xylanase leaked into the medium.
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| 6. |
- Nordberg Karlsson, Eva, et al.
(författare)
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Evidence for substrate binding of a recombinant thermostable xylanase originating from Rhodothermus marinus
- 1998
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Ingår i: FEMS Microbiology Letters. - 0378-1097. ; 168:1, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- The xyn1 encoded 5 domain xylanase from the thermophilic bacterium Rhodothermus marinus binds specifically to xylan, β-glucan and amorphous but not crystalline cellulose. Our results show that the binding is mediated by the full length xylanase, but not by the catalytic domain only. Based on similarities concerning both predicted secondary structure and binding specificity found with one cellulose binding domain of CenC from Cellulomonas fimi, we suggest that the binding is mediated by the two N-terminally repeated domains. Copyright (C) 1998 Federation of European Microbiological Societies.
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| 7. |
- Olsson, Gunnel, et al.
(författare)
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Microbial Desulfurization of Coal and Oxidation of Pure Pyrite by T. ferrooxidans and Acidianus brierleyi
- 1995
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Ingår i: Journal of Industrial Microbiology. - 0169-4146. ; 14:5, s. 420-423
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Tidskriftsartikel (refereegranskat)abstract
- Thiobacillus ferrooxidans and Acidianus brierleyi were capable of oxidizing pure pyrite as well as oxidizing sulfur in coal. First order reactions were assumed in the kinetic analysis performed. For oxidation of pure pyrite the rate constant was higher for A. brierleyi than for T. ferrooxidans. For sulfur removal from coal the values of the rate constants were comparable far the two microorganisms.
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| 8. |
- Olsson, G, et al.
(författare)
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Microbial desulfurization of different coal types
- 1995
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Ingår i: Coal Science (Coal Science and Technology ). - 0167-9449. - 0444822275 ; 24, s. 1741-1744
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Konferensbidrag (refereegranskat)abstract
- This chapter discusses different coals compared with respect to the extent of sulfur removal and jarosite formation when processed with A. brierleyi. All coals are of low-sulfur type with a sulfur content ranging from 0.6 % through 1.8 %. The efficiency of the microbial processing of coal depends on three factors––namely, the rate of sulfur removal, the extent of sulfur removal, and the formation of jarosite. Each coal contains one part sulfur available for removal during microbial processing. The available sulfur can in most cases be deduced to pyritic and sulfatic sulfur, the latter representing a minor fraction of the total sulfur.
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| 9. |
- Pott, B. M., et al.
(författare)
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Consecutive Desulphurization of Coal with T. ferrooxidans and Acidianus brierleyi
- 1995
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Ingår i: Resource and Environmental Biotechnology. - 1358-2283. ; 1:1, s. 21-32
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Tidskriftsartikel (refereegranskat)abstract
- hree different types of bituminous coal were subjected to microbial desulphurization in bench scale slurry reactors. Consecutive treatment with two microorganism species was used to test if different sulphur forms could be removed. The treatment started with the bacterium Thiobacillus ferrooxidans followed by the archaeon Acidianus brierleyi. Consecutive treatment did not desulphurize the three tested types of bituminous coal any better than use of only one of the microorganisms. Sulphur normally reported as organic sulphur was not significantly affected by the treatment. Final content of pyritic sulphur was less than 0.1% after consecutive treatment, as well as after use of either T. ferrooxidans or A. brierleyi.
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