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- Brandberg, T., et al.
(författare)
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Continuous fermentation of wheat-supplemented lignocellulose hydrolysate with different types of cell retention
- 2007
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Ingår i: Biotechnology and Bioengineering. - : John Wiley & Sons, Inc.. - 0006-3592 .- 1097-0290. ; 98:1, s. 80-
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Tidskriftsartikel (refereegranskat)abstract
- Medium supplementation and process alternatives for fuel ethanol production from dilute acid lignocellulose hydrolysate were investigated. Dilute acid lignocellulose hydrolysate supplemented with enzymatically hydrolysed wheat flour could sustain continuous anaerobic cultivation of Saccharomyces cerevisiae ATCC 96581 if further supplemented with ammonium sulphate and biotin. This medium composition allowed for a hexose utilisation of 73% and an ethanol production of 36 mmol l-1 h-1 in chemostat cultivation at dilution rate 0.10 h-1. Three different methods for cell retention were compared for improved fermentation of supplemented lignocellulose hydrolysate: cell recirculation by filtration, cell recirculation by sedimentation and cell immobilisation in calcium alginate. All three cell retention methods improved the hexose conversion and increased the volumetric ethanol production rate. Recirculation of 75% of the bioreactor outlet flow by filtration improved the hexose utilisation from 76% to 94%. Sedimentation turned out to be an efficient method for cell separation; the cell concentration in the reactor was 32 times higher than in the outflow after 60 h of substrate feeding. However, chemostat and continuous cell recirculation cultures became severely inhibited when the dilution rate was increased to 0.20 h-1. In contrast, an immobilised system kept producing ethanol at a stable level also at dilution rate 0.30 h-1. Biotechnol. Bioeng. 2007; 98: 80-90. © 2007 Wiley Periodicals, Inc.
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| 13. |
- Karimi, Keikhosro, et al.
(författare)
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Fed-batch cultivation of Mucor indicus in dilute-acid lignocellulosic hydrolyzate for ethanol production
- 2005
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Ingår i: BIOTECHNOLOGY LETTERS. - : Springer Science and Business Media LLC. - 0141-5492 .- 1573-6776. ; 27:18
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Tidskriftsartikel (refereegranskat)abstract
- Mucor indicus fermented dilute-acid lignocellulosic hydrolyzates to ethanol in fed-batch cultivation with complete hexose utilization and partial uptake of xylose. The fungus was tolerant to the inhibitors present in the hydrolyzates. It grew in media containing furfural (1 g/l), hydroxymethylfurfural (1 g/l), vanillin (1 g/l), or acetic acid (7 g/l), but did not germinate directly in the hydrolyzate. However, with fed-batch methodology, after initial growth of M. indicus in 500 ml enzymatic wheat hydrolyzate, lignocellulosic hydrolyzate was fermented with feeding rates 55 and 100 ml/h. The fungus consumed more than 46% of the initial xylose, while less than half of this xylose was excreted in the form of xylitol. The ethanol yield was 0.43 g/g total consumed sugar, and reached the maximum concentration of 19.6 g ethanol/l at the end of feeding phase. Filamentous growth, which is regarded as the main obstacle to large-scale cultivation of M. indicus, was avoided in the fed-batch experiments.
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- Purwadi, R., et al.
(författare)
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A Possible Industrial Solution to Ferment Lignocellulosic Hydrolyzate to Ethanol : Continuous Cultivation with Flocculating Yeast
- 2007
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Ingår i: International Journal of Molecular Sciences. - : Molecular Diversity Preservation International (MDPI) AG.. - 1661-6596 .- 1422-0067. ; 8:9, s. 920-932
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Tidskriftsartikel (refereegranskat)abstract
- Cultivation of toxic lignocellulosic hydrolyzates has been a research topic in recent decades. Although several methods have been proposed, there has been doubt about their industrial applications. The current work deals with a solution to this problem which has a good potential application in industrial scale. A toxic dilute-acid hydrolyzate was continuously cultivated using a high-cell-density flocculating yeast in a single and serial bioreactor which was equipped with a settler to recycle the cells back to the bioreactors. No prior detoxification was necessary to cultivate the hydrolyzates, as the flocks were able to detoxify it in situ. The experiments were successfully carried out at dilution rates up to 0.52 h-1. The cell concentration inside the bioreactors was between 23 and 35 g-DW/L, while this concentration in the effluent of the settlers was 0.320.05 g-DW/L. The ethanol yield of 0.42-0.46 g/g-consumed sugar was achieved, and the residual sugar concentration was less than 6% of the initial fermentable sugar (glucose, galactose and mannose) of 35.2 g/L.
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| 16. |
- Samuelsson, J., et al.
(författare)
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A phase II trial of pegylated interferon a-2b therapy for polycythemia vera and essential thrombocythemia : Feasibility, clinical and biologic effects, and impact on quality of life
- 2006
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Ingår i: Cancer. - : Wiley. - 0008-543X .- 1097-0142. ; 106:11, s. 2397-2405
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND. Conventional interferon-a (IFN) is an effective treatment for patients with myeloproliferative disorders. However, many patients discontinue therapy because of side effects. METHODS. In this 24-month, Phase II feasibility study of pegylated interferon a-2b (PEG-IFN) treatment, a starting dose of 0.5 µg/kg per week was received by 21 patients with polycythemia vera (PV) and 21 patients with essential thrombocythemia (ET). The treatment objective, a complete platelet response (CR), was a platelet count <400 × 109/L in symptomatic patients and <600 in asymptomatic patients. Neutrophil polycythemia rubra vera-1 (PRV-1) messenger RNA expression was analyzed prior to and during therapy. Quality of life (QoL) was investi-gated by using the European Organization for Research and Treatment of Cancer QLQ-C30 questionnaire. RESULTS. At 6 months, 29 of 42 patients (69%) had achieved a CR after a median of 83 days. The CR rate was not related to diagnosis, gender, or previous therapy. Nineteen patients completed the planned 2-year treatment in CR. No thromboembolic or bleeding complications were observed. Phlebotomy requirements were reduced in the majority of patients with PV. Five of 14 patients (36%) who initially were positive for PRV-1 achieved normalized PRV-1 expression under PEG-IFN treatment. Side effects were the cause of therapy failure in 16 of 23 patients. However, only 8 of 19 patients reported any side effects at 2 years. The QLQ-C30 revealed clinically significant impairments in several aspects of QoL at 6 months, however, at 2 years, QoL measurements were not different from baseline. CONCLUSIONS. PEG-IFN effectively reduced platelet counts in 29 of 42 patients, but only 19 patients maintained a CR at 2 years. The reversal of PRV-1 positivity noted in a subset of patients suggested that PEG-IFN may have an effect on the malignant clone. PEG-IFN is a valuable therapeutic alternative for patients who tolerate its initial side effects. © 2006 American Cancer Society.
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