| 1. |
- Andersson, Henrik, et al.
(författare)
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Assaying cardiac biomarkers for toxicity testing using biosensing and cardiomyocytes derived from human embryonic stem cells
- 2010
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Ingår i: JOURNAL OF BIOTECHNOLOGY. - : Elsevier Science B.V., Amsterdam.. - 0168-1656 .- 1873-4863. ; 150:1, s. 175-181
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Tidskriftsartikel (refereegranskat)abstract
- Human embryonic stem cell (hESC) derived cardiomyocytes are in the present study being used for testing drug-induced cardiotoxicity in a biosensor set-up. The design of an in vitro testing alternative provides a novel opportunity to surpass previous methods based on rodent cells or cell lines due to its significantly higher toxicological relevance. In this report we demonstrate how hESC-derived cardiomyocytes release detectable levels of two clinically decisive cardiac biomarkers, cardiac troponin T and fatty acid binding protein 3, when the cardiac cells are exposed to the well-known cardioactive drug compound. doxorubicin. The release is monitored by the immuno-biosensor technique surface plasmon resonance, particularly appropriate due to its capacity for parallel and high-throughput analysis in complex media.
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| 2. |
- Bettiga, Maurizio, et al.
(författare)
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Acoustophoretic Separation of Yeast Cells
- 2010
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Ingår i: Journal of Biotechnology. - : Elsevier BV. - 1873-4863 .- 0168-1656. ; 150:Suppl. 1, s. 522-522
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Konferensbidrag (refereegranskat)
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| 3. |
- Brolen, Gabriella, et al.
(författare)
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Hepatocyte-like cells derived from human embryonic stem cells specifically via definitive endoderm and a progenitor stage
- 2010
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Ingår i: Journal of Biotechnology. - : Elsevier BV. - 1873-4863 .- 0168-1656. ; 145:3, s. 284-294
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Tidskriftsartikel (refereegranskat)abstract
- Human embryonic stem cells offer a potential unlimited supply for functional hepatocytes, since they can differentiate into hepatocyte-like cells displaying a characteristic hepatic morphology and expressing various hepatic markers. These cells could be used in various applications such as studies of drug metabolism and hepatotoxicity, which however, would require a significant expression of drug metabolizing enzymes. To derive these cells we use a stepwise differentiation protocol where growth- and maturation factors are added. The first phase involves the formation of definitive endoderm. Next, these cells are treated with factors known to promote the induction and proliferation towards hepatic progenitor cell types. In the last phase the cells are terminally differentiated and maturated into functional hepatocyte-like cells. The cultures were characterized by analysis of endodermal or hepatic markers and compared to cultures derived without induction via definitive endoderm. Hepatic functions such as urea secretion, glycogen storage, indocyanine green uptake and secretion, and cytochrome P450-expression and activity were evaluated. The DE-Hep showed a hepatocyte morphology with sub-organized cells and exhibited many liver-functions including transporter activity and capacity to metabolize drugs specific for important cytochrome P450 sub-families. This represents an importantstep in differentiation of hESC into functional hepatocytes. (C) 2009 Elsevier B.V. All rights reserved.
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| 4. |
- Buehligen, Franziska, et al.
(författare)
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Analysis of aging in lager brewing yeast during serial repitching
- 2014
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Ingår i: Journal of Biotechnology. - : Elsevier BV. - 0168-1656 .- 1873-4863. ; 187, s. 60-70
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Tidskriftsartikel (refereegranskat)abstract
- Serial repitching of brewing yeast inoculates is an important economic factor in the brewing industry, as their propagation is time and resource intensive. Here, we investigated whether replicative aging and/or the population distribution status changed during serial repitching in three different breweries with the same brewing yeast strain but different abiotic backgrounds and repitching regimes with varying numbers of reuses. Next to bud scar numbers the DNA content of the Saccharomyces pastorianus HEBRU cells was analyzed. Gene expression patterns were investigated using low-density microarrays with genes for aging, stress, storage compound metabolism and cell cycle. Two breweries showed a stable rejuvenation rate during serial repitching. In a third brewery the fraction of virgin cells varied, which could be explained with differing wort aeration rates. Furthermore, the number of bud scars per cell and cell size correlated in all 3 breweries throughout all runs. Transcriptome analyses revealed that from the 6th run on, mainly for the cells positive gene expression could be seen, for example up-regulation of trehalose and glycogen metabolism genes. Additionally, the cells' settling in the cone was dependent on cell size, with the lowest and the uppermost cone layers showing the highest amount of dead cells. In general, cells do not progressively age during extended serial repitching.
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| 5. |
- Buehligen, Franziska, et al.
(författare)
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Sustainability of industrial yeast serial repitching practice studied by gene expression and correlation analysis
- 2013
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Ingår i: Journal of Biotechnology. - : Elsevier BV. - 0168-1656 .- 1873-4863. ; 168:4, s. 718-728
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Tidskriftsartikel (refereegranskat)abstract
- Bottom-fermenting Saccharomyces pastorianus strains driving brewing fermentation processes are usually reused several times. It is still unclear, whether the number of successions may have an impact on cell physiology prompting consequences for brewing quality. In this study, fermentation performance of up to twenty consecutive runs in a brewery was investigated. For each run mRNA expression levels of cellular marker molecules, which are known to correlate with metabolism, hexose transport, aging processes, stress response mechanisms and flocculation capability was estimated to obtain information on changes in cell physiology over the successive runs. Low-density microarrays were used for this purpose and the resulting gene expression profiles were finally correlated with changes in the abiotic micro-environments. A surprising stability of the marker molecule expression profiles within each specific serial repitching was stated. Loss of flocculation or an advanced aging could not be detected during serial repitching in the analyzed brewery. However, certain runs of the serial repitchings showed high variation in stress response which was found to be caused by perturbations of the abiotic conditions. Regardless, the study showed that S. pastorianus can be used repeatedly in serial repitching processes without loss of prominent physiological characteristics.
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| 6. |
- Cheregi, Otilia, et al.
(författare)
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The search for new chlorophyll-binding proteins in the cyanobacterium Synechocystis sp. PCC 6803
- 2012
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Ingår i: Journal of Biotechnology. - : Elsevier. - 0168-1656 .- 1873-4863. ; 162:1, s. 124-133
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Tidskriftsartikel (refereegranskat)abstract
- Light harvesting provides a major challenge in the production of biofuels from microorganisms; while sunlight provides the energy necessary for biomass/biofuel production, at the same time it damages the cells. The genome of Synechocystis sp. PCC 6803 was searched for open reading frames that might code for yet unidentified chlorophyll-binding proteins with low molecular mass that could be involved in stress-adaptation. Amongst 9,167 hypothetical ORFs corresponding to potential polypeptides of 100 amino acids or less, two were identified that had the potential to be pigment-binding, because they i) encoded a potential transmembrane region, ii) showed sequence similarity with known chlorophyll-binding domains, iii) were conserved in other cyanobacterial species, and iv) their codon adaptation index indicated significant translation probability. The two ORFs were located complementary (antisense) and internal to the ferrochelatase (hemH) and the pyruvate dehydrogenase (pdh) genes and therefore were named a-fch and a-pdh, respectively. Transcription of both genes was confirmed; however, no translated proteins could be detected immunologically. Whereas mutations within a-pdh or a-fch did not lead to any obvious phenotype, it is clear that transcripts and proteins over and above the currently known set may play a role in defining the physiology of cyanobacteria and other organisms.
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| 7. |
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| 8. |
- Doan Van, Thuoc, et al.
(författare)
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High productivity of ectoines by Halomonas boliviensis using a combined two-step fed-batch culture and milking process.
- 2010
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Ingår i: Journal of Biotechnology. - : Elsevier BV. - 1873-4863 .- 0168-1656. ; 147:1, s. 46-51
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Tidskriftsartikel (refereegranskat)abstract
- A process comprising two-step fed-batch cultivation has been investigated for the production of ectoines using the halophilic bacterium Halomonas boliviensis DSM 15516(T). The first cultivation was performed under optimal conditions for cell growth and resulted in cell mass concentration of about 41gl(-1) after 24h of cultivation. During the second cultivation at higher salt concentration, accumulation of ectoines increased while cell mass decreased with increasing salt concentration. Maximum productivity of total ectoines reached was 10gl(-1)d(-1) with ectoine concentration of 6gl(-1) and hydroxyectoine concentration of 8gl(-1) after 9h of cultivation at 18.5% NaCl, which is among the highest reported so far. H. boliviensis cells were further recycled for the production process after releasing the ectoines. About 75% of the accumulated ectoines were released by subjecting the cells to hypoosmotic shock. On subsequent reincubation in a medium containing higher salt concentration the cells were able to re-synthesize the ectoines resulting in a global productivity of 11.1gl(-1)d(-1), and ectoine and hydroxyectoine productivities of 9.1gl(-1)d(-1) and 2.0gl(-1)d(-1), respectively.
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| 9. |
- Erdei, Borbala, et al.
(författare)
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Glucose and xylose co-fermentation of pretreated wheat straw using mutants of S. cerevisiae TMB3400.
- 2013
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Ingår i: Journal of Biotechnology. - : Elsevier BV. - 1873-4863 .- 0168-1656. ; 164:1, s. 50-58
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Tidskriftsartikel (refereegranskat)abstract
- Wheat straw was pretreated and fermented to ethanol. Two strains, which had been mutated from the genetically modified Saccharomyces cerevisiae TMB3400, KE6-12 and KE6-13i, have been used in this study and the results of performance were compared to that of the original strain. The glucose and xylose co-fermentation ability was investigated in batch fermentation of steam-pretreated wheat straw (SPWS) liquid (undiluted, and diluted 1.5 and 2 times). Both strains showed improved xylose uptake in diluted SPWS liquid, and increased ethanol yields compared with the original TMB3400 strain, although xylitol formation also increased slightly. In undiluted SPWS liquid, however, only KE6-13i performed better than the original strain regarding xylose utilization. Fed-batch fermentation of 1.5 and 2 times diluted liquid was performed by adding the glucose-rich hydrolysates from enzymatic hydrolysis of the solid fraction of SPWS at a constant feed rate after 5h of fermentation, when the glucose had been depleted. The modified strains showed improved xylose conversion; however, the ethanol yield was not significantly improved due to increased glycerol production. Fed-batch fermentation resulted in faster xylose utilization than in the batch cases.
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| 10. |
- Gerlach, Inga, et al.
(författare)
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Operator training in recombinant protein production using a structured simulator model
- 2014
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Ingår i: Journal of Biotechnology. - : Elsevier. - 0168-1656 .- 1873-4863. ; 177, s. 53-59
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Tidskriftsartikel (refereegranskat)abstract
- Model-based operator training simulators ( OTS) could be powerful tools for virtual training of operational procedures and skills of production personnel in recombinant protein processes. The applied model should describe critical events in the bioprocess so accurately that the operators ability to observe and alertly act upon these events is trained with a high degree of efficiency. In this work is shown how this is accomplished in a structured multi-compartment model for the production of a recombinant protein in an Escherichia coli fed-batch process where in particular the induction procedure, the stress effects and overflow metabolism were highlighted. The structured model was applied on the OTS platform that virtually simulated the operational bioreactor procedures in real or accelerated time. Evaluation of training using the model-based OTS showed that trained groups of operators exhibited improved capability compared with the untrained groups when subsequently performing real laboratory scale cultivations. The results suggest that this model-based OTS may provide a valuable resource for enhancing operator skills in large scale recombinant protein manufacturing.
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