| 1. |
- Helmerius, Jonas, et al.
(author)
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Production of value added chemicals from xylan extraction in a Kraft pulp mill and the effect on pulp quality
- 2008
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Conference paper (other academic/artistic)abstract
- In the Kraft process hemicelluloses are lost in the cooking procedure to the black liquor stream, which is subsequently burnt in the recovery boiler to recover cooking chemicals and to produce steam and energy. Hemicelluloses have a low heating value compared to lignin and therefore recovery of hemicelluloses at an earlier stage of the Kraft process followed by biochemical conversionintohighvalue-conversion intohighvalue-into high value-added products might offer a muchbettereconomicopportunity.much better economic opportunityIn collaboration with the research and development department of Smurfit Kappa Kraftliner AB, Piteå, Sweden, alkali and water extractions of birch wood were performed under conditions compatible with the Kraft process, at different times, temperatures and alkali charges. The extraction conditions were set in a range suitable with the current pulp process at Smurfit Kappa Kraftliner. TherequirementsforprocessThe requirements for process configurations, based on either hot water or alkali extraction were also explored. ThexylanyieldsfromdifferentextractiontrialswereThe xylan yields from different extraction trials were measured and the chips from those extraction trials were cooked, refined and turned into sheets of paper. The effects on paper quality were compared with a reference pulp made from the same wooden chips. Recovered xylans from water extracted birch wood chips were subjected to secondary hydrolysis, enzymatic or sulphuricacid.sulphuric acidDetoxification of the hydrolysate with active carbon and regulation of pH were performed before fermentation. FermentationofthexyloseFermentation of the xylose hydrolysate to succinic acid was demonstrated by the use of thethe succinic acid producer Escherichia coli AFP184.
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| 2. |
- Helmerius, Jonas, et al.
(author)
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Production of value added chemicals from xylan extraction in a Kraft pulp mill and the effect on pulp quality
- 2008
-
Conference paper (other academic/artistic)abstract
- In the Kraft process hemicelluloses are lost in the cooking procedure to the black liquor stream, which is subsequently burnt in the recovery boiler to recover cooking chemicals and to produce steam and energy. Hemicelluloses have a low heating value compared to lignin and therefore recovery of hemicelluloses at an earlier stage of the Kraft process followed by biochemical conversion into high value-added products might offer a much better economic opportunity. In collaboration with the research and development department of Smurfit Kappa Kraftliner AB, Piteå, Sweden, alkali and water extractions of birch wood were performed under conditions compatible with the Kraft process, at different times, temperatures and alkali charges. The extraction conditions were set in a range suitable with the current pulp process at Smurfit Kappa Kraftliner. The requirements for process configurations, based on either hot water or alkali extraction were also explored. The xylan yields from different extraction trials were measured and the chips from those extraction trials were cooked, refined and turned into sheets of paper. The effects on paper quality were compared with a reference pulp made from the same wooden chips. Recovered xylans from water extracted birch wood chips were subjected to secondary hydrolysis, enzymatic or sulphuric acid. Detoxification of the hydrolysate with active carbon and regulation of pH were performed before fermentation. Fermentation of the xylose hydrolysate to succinic acid was demonstrated by the use of the succinic acid producer Escherichia coli AFP184.
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| 3. |
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| 4. |
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| 5. |
- Allen, N. E., et al.
(author)
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Animal foods, protein, calcium and prostate cancer risk: the European Prospective Investigation into Cancer and Nutrition
- 2008
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In: British Journal of Cancer. - : Springer Science and Business Media LLC. - 1532-1827 .- 0007-0920. ; 98:9, s. 1574-1581
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Journal article (peer-reviewed)abstract
- We examined consumption of animal foods, protein and calcium in relation to risk of prostate cancer among 142 251 men in the European Prospective Investigation into Cancer and Nutrition. Associations were examined using Cox regression, stratified by recruitment centre and adjusted for height, weight, education, marital status and energy intake. After an average of 8.7 years of follow-up, there were 2727 incident cases of prostate cancer, of which 1131 were known to be localised and 541 advanced-stage disease. A high intake of dairy protein was associated with an increased risk, with a hazard ratio for the top versus the bottom fifth of intake of 1.22 (95% confidence interval (CI): 1.07-1.41, P-trend = 0.02). After calibration to allow for measurement error, we estimated that a 35-g day(-1) increase in consumption of dairy protein was associated with an increase in the risk of prostate cancer of 32% (95% CI: 1-72%, P-trend = 0.04). Calcium from dairy products was also positively associated with risk, but not calcium from other foods. The results support the hypothesis that a high intake of protein or calcium from dairy products may increase the risk for prostate cancer.
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| 6. |
- Andersson, Christian, et al.
(author)
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Effects of neutralising agent, organic acids, and osmolarity on succinic acid production by Escherichia coli AFP184
- 2008
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Conference paper (other academic/artistic)abstract
- Using a low-cost medium Escherichia coli AFP184 has previously been reported to produce succinic acid with volumetric productivities close to 3 g L-1 h-1. At a total organic acid concentration of 30 g L-1 the productivity decreased drastically resulting in final succinate concentrations of 40 g L-1. The economical viability of biochemical succinic acid production would benefit from higher final succinic acid concentrations and volumetric productivities maintained at >2.5 g L-1 h-1 for an extended period of time. In the present work the effects of osmolarity and neutralising agent (NH4OH, KOH, NaOH, K2CO3, and Na2CO3) on succinic acid production by AFP184 were investigated. Highest concentration of succinic acid was obtained with Na2CO3, 75 g L-1. It was also found that the osmolarity resulting from succinate production and subsequent base addition, only marginally affected the productivity per viable cell. Organic acid inhibition due to the produced succinic acid on the other hand significantly reduced succinic acid productivity per viable cell. When using NH4OH productivity completely ceased at approximately 40 g L-1. Volumetric productivities remained at 2.5 g L-1 h-1 for 5 to 10 hours longer when using K- or Na-bases than when using NH4OH. However, loss of cell viability occurred, and together with the acid inhibition decreased the volumetric productivities. In this study it was demonstrated that by altering the neutralising agent it was possible to increase the period of high volumetric productivity in the anaerobic phase and improve the final succinic acid concentration by almost 100 %
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| 7. |
- Andersson, Christian, et al.
(author)
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Inhibition of succinic acid production in metabolically engineered Escherichia Coli by neutralizing agent, organic acids, and osmolarity
- 2009
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In: Biotechnology progress (Print). - : Wiley. - 8756-7938 .- 1520-6033. ; 25:1, s. 116-123
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Journal article (peer-reviewed)abstract
- The economical viability of biochemical succinic acid production is a result of many processing parameters including final succinic acid concentration, recovery of succinate, and the volumetric productivity. Maintaining volumetric productivities >2.5 g L-1 h(-1) is important if production of succinic acid from. renewable resources should be competitive. In this work, the effects of organic acids, osmolarity, and neutralizing agent (NH4OH, KOH, NaOH, K2CO3, and Na2CO3) on the fermentative succinic acid production by Escherichia coli AFP184 were investigated. The highest concentration of succinic acid, 77 g L-1. was obtained with Na2O3. In general, irrespective of the base used, succinic acid productivity per viable cell was significantly reduced as the concentration of the produced acid increased. Increased osmolarity resulting from base addition during succinate production only marginally affected the productivity per viable cell. Addition of the osmoprotectant glycine betaine to cultures resulted in an increased aerobic growth rate and anaerobic glucose consumption rate, but decreased succinic acid yield. When using NH4OH productivity completely ceased at a succinic acid concentration of similar to 40 g L-1. Volumetric productivities remained at 2.5 g L-1 h(-1) for tip to 10 h longer when K- or Na-bases where used instead of NH4OH. The decrease in cellular succinic acid productivity observed during the anaerobic phase was found to be due to increased organic acid concentrations rather than medium osmolarity.
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| 8. |
- Berglund, Jonas, et al.
(author)
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Hotspots of biased nucleotide substitutions in human genes
- 2009
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In: PLoS biology. - : Public Library of Science (PLoS). - 1544-9173 .- 1545-7885. ; 7:1, s. e26-
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Journal article (peer-reviewed)abstract
- Genes that have experienced accelerated evolutionary rates on the human lineage during recent evolution are candidates for involvement in human-specific adaptations. To determine the forces that cause increased evolutionary rates in certain genes, we analyzed alignments of 10,238 human genes to their orthologues in chimpanzee and macaque. Using a likelihood ratio test, we identified protein-coding sequences with an accelerated rate of base substitutions along the human lineage. Exons evolving at a fast rate in humans have a significant tendency to contain clusters of AT-to-GC (weak-to-strong) biased substitutions. This pattern is also observed in noncoding sequence flanking rapidly evolving exons. Accelerated exons occur in regions with elevated male recombination rates and exhibit an excess of nonsynonymous substitutions relative to the genomic average. We next analyzed genes with significantly elevated ratios of nonsynonymous to synonymous rates of base substitution (dN/dS) along the human lineage, and those with an excess of amino acid replacement substitutions relative to human polymorphism. These genes also show evidence of clusters of weak-to-strong biased substitutions. These findings indicate that a recombination-associated process, such as biased gene conversion (BGC), is driving fixation of GC alleles in the human genome. This process can lead to accelerated evolution in coding sequences and excess amino acid replacement substitutions, thereby generating significant results for tests of positive selection.
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