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  • 1. Anasontzis, George E.
    et al.
    Pena, Margarita Salazar
    Spadiut, Oliver
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Brumer, Harry
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Olsson, Lisbeth
    Effects of temperature and glycerol and methanol-feeding profiles on the production of recombinant galactose oxidase in Pichia pastoris2014In: Biotechnology progress (Print), ISSN 8756-7938, E-ISSN 1520-6033, Vol. 30, no 3, p. 728-735Article in journal (Refereed)
    Abstract [en]

    Optimization of protein production from methanol-induced Pichia pastoris cultures is necessary to ensure high productivity rates and high yields of recombinant proteins. We investigated the effects of temperature and different linear or exponential methanol-feeding rates on the production of recombinant Fusarium graminearum galactose oxidase (EC 1.1.3.9) in a P. pastoris Mut+ strain, under regulation of the AOX1 promoter. We found that low exponential methanol feeding led to 1.5-fold higher volumetric productivity compared to high exponential feeding rates. The duration of glycerol feeding did not affect the subsequent product yield, but longer glycerol feeding led to higher initial biomass concentration, which would reduce the oxygen demand and generate less heat during induction. A linear and a low exponential feeding profile led to productivities in the same range, but the latter was characterized by intense fluctuations in the titers of galactose oxidase and total protein. An exponential feeding profile that has been adapted to the apparent biomass concentration results in more stable cultures, but the concentration of recombinant protein is in the same range as when constant methanol feeding is employed.

  • 2. Andersson, Christian
    et al.
    Helmerius, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Hodge, David
    Berglund, Kris
    Rova, Ulrika
    Inhibition of succinic acid production in metabolically engineered Escherichia Coli by neutralizing agent, organic acids, and osmolarity2009In: Biotechnology progress (Print), ISSN 8756-7938, E-ISSN 1520-6033, Vol. 25, no 1, p. 116-123Article in journal (Refereed)
    Abstract [en]

    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.

  • 3. Andersson, Christian
    et al.
    Hodge, David
    Berglund, Kris
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Rova, Ulrika
    Effect of different carbon sources on the production of succinic acid using metabolically engineered Escherichia coli2007In: Biotechnology progress (Print), ISSN 8756-7938, E-ISSN 1520-6033, Vol. 23, no 2, p. 381-388Article in journal (Refereed)
    Abstract [en]

    Succinic acid (SA) is an important platform molecule in the synthesis of a number of commodity and specialty chemicals. In the present work, dual-phase batch fermentations with the E. coli strain AFP184 were performed using a medium suited for large-scale industrial production of SA. The ability of the strain to ferment different sugars was investigated. The sugars studied were sucrose, glucose, fructose, xylose, and equal mixtures of glucose and fructose and glucose and xylose at a total initial sugar concentration of 100 g L-1. AFP184 was able to utilize all sugars and sugar combinations except sucrose for biomass generation and succinate production. For sucrose as a substrate no succinic acid was produced and none of the sucrose was metabolized. The succinic acid yield from glucose (0.83 g succinic acid per gram glucose consumed anaerobically) was higher than the yield from fructose (0.66 g g-1). When using xylose as a carbon source, a yield of 0.50 g g-1 was obtained. In the mixed-sugar fermentations no catabolite repression was detected. Mixtures of glucose and xylose resulted in higher yields (0.60 g g-1) than use of xylose alone. Fermenting glucose mixed with fructose gave a lower yield (0.58 g g-1) than fructose used as the sole carbon source. The reason is an increased pyruvate production. The pyruvate concentration decreased later in the fermentation. Final succinic acid concentrations were in the range of 25-40 g L-1. Acetic and pyruvic acid were the only other products detected and accumulated to concentrations of 2.7-6.7 and 0-2.7 g L-1. Production of succinic acid decreased when organic acid concentrations reached approximately 30 g L-1. This study demonstrates that E. coli strain AFP184 is able to produce succinic acid in a low cost medium from a variety of sugars with only small amounts of byproducts formed.

  • 4.
    Bijmans, Martijn F M
    et al.
    Wageningen University and Research Centre, Wageningen, The Netherlands.
    de Vries, Erik
    Wageningen University and Research Centre, Wageningen, The Netherlands.
    Yang, Chun-Hui
    Umeå University.
    N Buisman, Cees J
    Wageningen University and Research Centre, Wageningen, The Netherlands.
    Lens, Piet N L
    Wageningen University and Research Centre, Wageningen, The Netherlands.
    Dopson, Mark
    Umeå University.
    Sulfate reduction at pH 4.0 for treatment of process and wastewaters.2010In: Biotechnology progress (Print), ISSN 8756-7938, E-ISSN 1520-6033, Vol. 26, no 4, p. 1029-1037Article in journal (Refereed)
    Abstract [en]

    Acidic industrial process and wastewaters often contain high sulfate and metal concentrations and their direct biological treatment is thus far not possible as biological processes at pH < 5 have been neglected. Sulfate-reducing bacteria convert sulfate to sulfide that can subsequently be used to recover metals as metal-sulfides precipitate. This study reports on high-rate sulfate reduction with a mixed microbial community at pH 4.0 and 4.5 with hydrogen and/or formate as electron donors. The maximum sulfate reducing activity at pH 4.0 was sustained for over 40 days with a specific activity 500-fold greater than previously reported values: 151 mmol sulfate reduced/L reactor liquid per day with a maximum specific activity of 84 mmol sulfate per gram of volatile suspended solids per day. The biomass yield gradually decreased from 38 to 0.4 g volatile suspended solids per kilogram of sulfate when decreasing the reactor pH from pH 6 to 4. The microorganisms had a high maintenance requirement probably due maintaining pH homeostasis and the toxicity of sulfide at low pH. The microbial community diversity in the pH 4.0 membrane bioreactor decreased over time, while the diversity of the sulfate reducing community increased. Thus, a specialized microbial community containing a lower proportion of microorganisms capable of activity at pH 4 developed in the reactor compared with those present at the start of the experiment. The 16S rRNA genes identified from the pH 4.0 grown mixed culture were most similar to those of Desulfovibrio species and Desulfosporosinus sp. M1.

  • 5. Bijmans, MFM
    et al.
    de Vries, E
    Yang, Chun-Hui
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Buisman, CJN
    Lens, PNL
    Dopson, Mark
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Sulfate reduction at pH 4.0 for treatment of process and wastewaters2010In: Biotechnology progress (Print), ISSN 8756-7938, E-ISSN 1520-6033, Vol. 26, no 4, p. 1029-1037Article in journal (Refereed)
    Abstract [en]

    Acidic industrial process and wastewaters often contain high sulfate and metal concentrations and their direct biological treatment is thus far not possible as biological processes at pH < 5 have been neglected. Sulfate-reducing bacteria convert sulfate to sulfide that can subsequently be used to recover metals as metal-sulfides precipitate. This study reports on high-rate sulfate reduction with a mixed microbial community at pH 4.0 and 4.5 with hydrogen and/or formate as electron donors. The maximum sulfate reducing activity at pH 4.0 was sustained for over 40 days with a specific activity 500-fold greater than previously reported values: 151 mmol sulfate reduced/L reactor liquid per day with a maximum specific activity of 84 mmol sulfate per gram of volatile suspended solids per day. The biomass yield gradually decreased from 38 to 0.4 g volatile suspended solids per kilogram of sulfate when decreasing the reactor pH from pH 6 to 4. The microorganisms had a high maintenance requirement probably due maintaining pH homeostasis and the toxicity of sulfide at low pH. The microbial community diversity in the pH 4.0 membrane bioreactor decreased over time, while the diversity of the sulfate reducing community increased. Thus, a specialized microbial community containing a lower proportion of microorganisms capable of activity at pH 4 developed in the reactor compared with those present at the start of the experiment. The 16S rRNA genes identified from the pH 4.0 grown mixed culture were most similar to those of Desulfovibrio species and Desulfosporosinus sp. M1. (C) 2010 American Institute of Chemical Engineers Biotechnol. Prog., 26: 1029-1037, 2010

  • 6. Bramble, J L
    et al.
    Graves, D J
    Brodelius, Peter
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Plant Cell Culture using a Novel Bioreactor: The Magnetically Stabilized Fluidized Bed1990In: Biotechnology progress (Print), ISSN 8756-7938, E-ISSN 1520-6033, Vol. 6, no 6, p. 452-457Article in journal (Refereed)
    Abstract [en]

    A novel bioreactor using magnetically stabilized fluidized bed (MSFB) technology has been developed that has certain advantages for cultivating cells continuously. In this system, the cells are protected from shear and are constrained to move through the fermenter in lock-step fashion by being immobilized in calcium alginate beads. The MSFB permits good mass transfer, minimizes particle collisions, and allows for the production of cells while maintaining a controlled cell residence time. Details of the experimental system are described. In addition, the experimental performance of an MSFB used to grow plant cells in batch mode is compared to the results obtained in shake flask culture. 

  • 7. Calles, Karin
    et al.
    Eriksson, Ulrika
    KTH, School of Biotechnology (BIO), Bioprocess Technology (closed 20130101).
    Häggström, Lena
    KTH, School of Biotechnology (BIO), Bioprocess Technology (closed 20130101).
    Effect of conditioned medium factors on productivity and cell physiology in Trichoplusia ni insect cell cultures.2006In: Biotechnology progress (Print), ISSN 8756-7938, E-ISSN 1520-6033, Vol. 22, no 3, p. 653-659Article in journal (Refereed)
    Abstract [en]

    The influence of conditioned medium (CM) on cell physiology and recombinant protein production in Trichoplusia ni insect cells (T. ni, BTI-Tn-5B1-4) has been investigated. Cell cycle analysis showed that a high proportion of the cell population (80-90%) was in G1 during the whole culture, indicating that the S and G2/M phases are short relative to the G1 phase. Directly after inoculation, a rapid decrease of the S-phase population occurred, which could be observed as a lag-phase. The following increase in the number of cells in S occurred after 7 h of culture for cells in fresh medium, whereas for cells with the addition of CM it occurred at an earlier time point (5 h) and these cells had therefore a shorter lag-phase. The initial changes in the S-phase population were also affected by the inoculum cell density, as higher seeding cell densities resulted in a more rapid increase in the S-phase population after inoculation. These changes in cell cycle distribution were reflected in the cell size, and the CM-cells were smaller than the cells in fresh medium. Recombinant protein production in T. ni cells was improved by the addition of CM. The specific productivity was increased by 30% compared to cells in fresh medium. This beneficial effect was seen between 20 and 72 h of culture. In contrast, the highest specific productivity was obtained already at 7 h for the cells in fresh medium and then decreased rapidly. The total product concentration was around 30% higher in the culture with CM compared to the culture in fresh medium, and the maximum product concentration was obtained on day 2 compared to day 3 for the cells in fresh medium. Our results indicate that the positive effect on productivity by CM is related to its growth-promoting effect, suggesting that the proliferation potential of the culture determines the productivity.

  • 8. Calles, Karin
    et al.
    Svensson, Ingrid
    Lindskog, Eva
    KTH, School of Biotechnology (BIO), Bioprocess Technology.
    Häggström, Lena
    Effects of conditioned medium factors and passage number on Sf9 cell physiology and productivity2006In: Biotechnology progress (Print), ISSN 8756-7938, E-ISSN 1520-6033, Vol. 22, no 2, p. 394-400Article in journal (Refereed)
    Abstract [en]

    The effects of conditioned medium (CM) and passage number on Spodoptera frugiperda Sf9 cell physiology and productivity have been studied. Low passage (LP) cells at passages 20-45 were compared to high passage (HP) cells at passages > 100. Addition of 20% CM or 10 kDa filtrated CM to LP cells promoted growth. LP cells passed a switch in growth kinetics, characterized by a shorter lag phase and a higher growth rate, after 30-40 passages. After this point, CM lost its stimulating effect on proliferation. HP cells displayed a still shorter lag phase and reached the maximum cell density 24-48 earlier than LP cells. HP cells also exhibited higher specific productivity of recombinant protein compared to LP cells, when infected with baculovirus during the initial 48 h of culture. The specific productivity of LP cells was decreased by 30-50% by addition of 20% CM or 10 kDa filtrated CM, whereas addition of CM to cells having passed the switch in growth kinetics had no negative effect on productivity. Cell cycle analysis showed that a large proportion of HP cells, >60%, was transiently arrested in G2/M after inoculation. In LP cultures this proportion was lower, 40-45%, and addition of CM decreased the arrested population further. This correlated to the cell size, the HP cells being the largest: HP cells > LP > LP + 20% CM > LP + 20% 10 kDa filtrated CM. Since the degree of synchronization in G2/M correlated to the productivity, yeastolate limitation was used to achieve 85% G2/M synchronized cells. In this culture the specific productivity was maintained during a prolonged production phase and a 69% higher volumetric yield was obtained. The results suggest that a decreasing degree of synchronization during the course of culture partly explains the cell-density-dependent drop in productivity in Sf9 cells.

  • 9. Cimander, C.
    et al.
    Bachinger, T.
    Mandenius, Carl-Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biotechnology .
    Assessment of the performance of a fed-batch cultivation from the preculture quality using an electronic nose2002In: Biotechnology progress (Print), ISSN 8756-7938, E-ISSN 1520-6033, Vol. 18, no 2, p. 380-386Article in journal (Refereed)
    Abstract [en]

    An electronic nose, a gas-phase multisensor system, was used to monitor precultivations of a recombinant tryptophan-producing Escherichia coli strain. The electronic nose signals showed a high correlation toward the main stages of the precultivations, namely, exponential growth, oxygen-limited growth, and glucose depletion. Principal component analysis (PCA) of the electronic nose signals was performed and shown to be useful for monitoring preculture progression. More importantly, PCA also allowed a qualitative assessment of the preculture performance during subsequent fed-batch cultivations. The electronic nose signals from the precultures showed, furthermore, a high correlation to the time of phosphate limitation and the tryptophan yield coefficient of the subsequent fed-batch cultivations, which allowed an accurate prediction of these process variables using partial least squares (PLS). The results demonstrate on data from 12 cultivations how the electronic nose can be a useful tool for the assessment of inoculum quality, thereby providing means of reducing batch-to-batch variation and increasing the productivity of bioprocesses.

  • 10.
    Clincke, Marie-Francoise
    et al.
    KTH, School of Biotechnology (BIO).
    Mölleryd, Carin
    KTH, School of Biotechnology (BIO).
    Samani, Puneeth K.
    KTH, School of Biotechnology (BIO).
    Lindskog, Eva
    Fäldt, Eric
    Walsh, Kieron
    Chotteau, Veronique
    KTH, School of Biotechnology (BIO), Bioprocess Technology.
    Very high density of Chinese hamster ovary cells in perfusion by alternating tangential flow or tangential flow filtration in WAVE bioreactorpart II: Applications for antibody production and cryopreservation2013In: Biotechnology progress (Print), ISSN 8756-7938, E-ISSN 1520-6033, Vol. 29, no 3, p. 768-777Article in journal (Refereed)
    Abstract [en]

    A high cell density perfusion process of monoclonal antibody (MAb) producing Chinese hamster ovary (CHO) cells was developed in disposable WAVE Bioreactor using external hollow fiber (HF) filter as cell separation device. Tangential flow filtration (TFF) and alternating tangential flow (ATF) systems were compared and process applications of high cell density perfusion were studied here: MAb production and cryopreservation. Operations by perfusion using microfiltration (MF) or ultrafiltration (UF) with ATF or TFF and by fed-batch were compared. Cell densities higher than 108 cells/mL were obtained using UF TFF or UF ATF. The cells produced comparable amounts of MAb in perfusion by ATF or TFF, MF or UF. MAbs were partially retained by the MF using ATF or TFF but more severely using TFF. Consequently, MAbs were lost when cell broth was discarded from the bioreactor in the daily bleeds. The MAb cell-specific productivity was comparable at cell densities up to 1.3 x 108 cells/mL in perfusion and was comparable or lower in fed-batch. After 12 days, six times more MAbs were harvested using perfusion by ATF or TFF with MF or UF, compared to fed-batch and 28x more in a 1-month perfusion at 108 cells/mL density. Pumping at a recirculation rate up to 2.75 L/min did not damage the cells with the present TFF settings with HF short circuited. Cell cryopreservation at 0.5 x 108 and 108 cells/mL was performed using cells from a perfusion run at 108 cells/mL density. Cell resuscitation was very successful, showing that this system was a reliable process for cell bank manufacturing.

  • 11.
    Clincke, Marie-Francoise
    et al.
    KTH, School of Biotechnology (BIO).
    Mölleryd, Carin
    KTH, School of Biotechnology (BIO).
    Zhang, Ye
    KTH, School of Biotechnology (BIO), Bioprocess Technology (closed 20130101).
    Lindskog, Eva
    Walsh, Kieron
    Chotteau, Veronique
    KTH, School of Biotechnology (BIO), Bioprocess Technology (closed 20130101).
    Very high density of CHO cells in perfusion by ATF or TFF in WAVE bioreactor. Part I. Effect of the cell density on the process2013In: Biotechnology progress (Print), ISSN 8756-7938, E-ISSN 1520-6033, Vol. 29, no 3, p. 754-767Article in journal (Refereed)
    Abstract [en]

    High cell density perfusion process of antibody producing CHO cells was developed in disposable WAVE Bioreactor using external hollow fiber filter as cell separation device. Both classical tangential flow filtration (TFF) and alternating tangential flow system (ATF) equipment were used and compared. Consistency of both TFF- and ATF-based cultures was shown at 20-35 x 106 cells/mL density stabilized by cell bleeds. To minimize the nutrients deprivation and by-product accumulation, a perfusion rate correlated to the cell density was applied. The cells were maintained by cell bleeds at density 0.9-1.3 x 108 cells/mL in growing state and at high viability for more than 2 weeks. Finally, with the present settings, maximal cell densities of 2.14 x 108 cells/mL, achieved for the first time in a wave-induced bioreactor, and 1.32 x 108 cells/mL were reached using TFF and ATF systems, respectively. Using TFF, the cell density was limited by the membrane capacity for the encountered high viscosity and by the pCO2 level. Using ATF, the cell density was limited by the vacuum capacity failing to pull the highly viscous fluid. Thus, the TFF system allowed reaching higher cell densities. The TFF inlet pressure was highly correlated to the viscosity leading to the development of a model of this pressure, which is a useful tool for hollow fiber design of TFF and ATF. At very high cell density, the viscosity introduced physical limitations. This led us to recommend cell densities under 1.46 x 108 cell/mL based on the analysis of the theoretical distance between the cells for the present cell line.

  • 12.
    Derelöv, Micael
    et al.
    Linköping University, Department of Management and Engineering, Assembly technology . Linköping University, The Institute of Technology.
    Detterfelt, Jonas
    Linköping University, Department of Management and Engineering, Assembly technology . Linköping University, The Institute of Technology.
    Björkman, Mats
    Linköping University, Department of Management and Engineering, Assembly technology . Linköping University, The Institute of Technology.
    Mandenius, Carl-Fredrik
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Engineering Design Methodology for Bio-Mechatronic Products2008In: Biotechnology progress (Print), ISSN 8756-7938, E-ISSN 1520-6033, Vol. 4, no 1, p. 232-244Article in journal (Refereed)
    Abstract [en]

    Four complex biotechnology products/product systems (a protein purification system, a bioreactor system, a surface plasmon resonance biosensor, and an enzymatic glucose analyzer) are analyzed using conceptual design principles. A design model well-known in mechanical system design, the Hubka-Eder (HE) model, is adapted to biotechnology products that exemplify combined technical systems of mechanical, electronic, and biological components, here referred to as bio-mechatronic systems. The analysis concludes that an extension of the previous HE model with a separate biological systems entity significantly contributes to facilitating the functional and systematic analyses of bio-mechatronic systems.

  • 13.
    Doverskog, Magnus
    et al.
    KTH, Superseded Departments, Biotechnology.
    Bertram, Eva.
    KTH, Superseded Departments, Biotechnology.
    Ljunggren, Jan
    Öhman, Lars
    Sennerstam, Roland
    Häggström, Lena
    KTH, Superseded Departments, Biotechnology.
    Cell cycle progression in serum-free cultures of Sf9 insect cells: Modulation by conditioned medium factors and implications for proliferation and productivity2000In: Biotechnology progress (Print), ISSN 8756-7938, E-ISSN 1520-6033, Vol. 16, no 5, p. 837-846Article in journal (Refereed)
    Abstract [en]

    Cell cycle progression was studied in serum-free batch cultures of Spodoptera frugiperda (Sf9) insect cells, and the implications for proliferation and productivity were investigated. Cell cycle dynamics in KBM10 serum-free medium was characterized by an accumulation of 50-70% of the cells in the G(2)/M phase of the cell cycle during the first 24 h after inoculation. Following the cell cycle arrest, the cell population was redistributed into G(1) and in particular into the S phase. Maximum rate of proliferation (mu(N,max)) was reached 24-48 h after the release from cell cycle arrest, coinciding with a minimum distribution of cells in the G(2)/M phase. The following declining mu(N) could be explained by a slow increase in the G(2)/M cell population. However, at approximately 100 h, an abrupt increase in the amount of G(2)/M cells occurred. This switch occurred at about the same time point and cell density, irrespective of medium composition and maximum cell density. An octaploid population evolved from G(2)/M arrested cells, showing the occurrence of endoreplication in this cell line. In addition, conditioned medium factor(s) were found to increase mu(N,max), decrease the time to reach mu(N,max), and decrease the synchronization of cells in G(2)/M during the lag and growth phase. A conditioned medium factor appears to be a small peptide. On basis of these results we suggest that the observed cell cycle dynamics is the result of autoregulatory events occurring at key points during the course of a culture, and that entry into mitosis is the target for regulation. Infecting the Sf9 cells with recombinant baculovirus resulted in a linear increase in volumetric productivity of beta-galactosidase up to 68-75 h of culture. Beyond this point almost no product was formed. Medium renewal at the time of infection could only partly restore the lost hypertrophy and product yield of cultures infected after the transition point. The critical time of infection correlated to the time when the mean;population cell volume had attained a minimum, and this occurred 24 h before the switch into the G(2)/M phase. We suggest that the cell density dependent decrease in productivity ultimately depends on the autoregulatory events leading to G(2)/M cell cycle arrest.

  • 14.
    Ferraz, Natalia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Surface Biotechnology.
    Leverrier, Julieta
    Biochemistry Department, University of the Republic, Uruguay.
    Batista-Viera, Francisco
    Biochemistry Department, University of the Republic, Uruguay.
    Manta, Carmen
    Biochemistry Department, University of the Republic, Uruguay.
    Thiopropyl-agarose as a solid phase reducing agent for chemical modification of IgG and F(ab´)22008In: Biotechnology progress (Print), ISSN 8756-7938, E-ISSN 1520-6033, Vol. 24, no 5, p. 1154-1159Article in journal (Refereed)
  • 15.
    Gowtham, Yogender Kumar
    et al.
    Clemson University.
    Miller, Kristen P.
    Clemson University.
    Hodge, David
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Henson, J. Michael
    Clemson University.
    Harcum, Sarah W.
    Clemson University.
    Novel two-stage fermentation process for bioethanol production using Saccharomyces pastorianus2014In: Biotechnology progress (Print), ISSN 8756-7938, E-ISSN 1520-6033, Vol. 30, no 2, p. 300-310Article in journal (Refereed)
    Abstract [en]

    Bioethanol produced from lignocellulosic materials has the potential to be economically feasible, if both glucose and xylose released from cellulose and hemicellulose can be efficiently converted to ethanol. Saccharomyces spp. can efficiently convert glucose to ethanol; however, xylose conversion to ethanol is a major hurdle due to lack of xylose-metabolizing pathways. In this study, a novel two-stage fermentation process was investigated to improve bioethanol productivity. In this process, xylose is converted into biomass via non-Saccharomyces microorganism and coupled to a glucose-utilizing Saccharomyces fermentation. Escherichia coli was determined to efficiently convert xylose to biomass, which was then killed to produce E. coli extract. Since earlier studies with Saccharomyces pastorianus demonstrated that xylose isomerase increased ethanol productivities on pure sugars, the addition of both E. coli extract and xylose isomerase to S. pastorianus fermentations on pure sugars and corn stover hydrolysates were investigated. It was determined that the xylose isomerase addition increased ethanol productivities on pure sugars but was not as effective alone on the corn stover hydrolysates. It was observed that the E. coli extract addition increased ethanol productivities on both corn stover hydrolysates and pure sugars. The ethanol productivities observed on the corn stover hydrolysates with the E. coli extract addition was the same as observed on pure sugars with both E. coli extract and xylose isomerase additions. These results indicate that the two-stage fermentation process has the capability to be a competitive alternative to recombinant Saccharomyces cerevisiae-based fermentations.

  • 16. Jahic, Mehmedalija
    et al.
    Veide, Andres
    KTH, School of Biotechnology (BIO), Bioprocess Technology.
    Charoenrat, Theppanya
    Teeri, Tuula T.
    KTH, School of Biotechnology (BIO), Glycoscience.
    Enfors, Sven-Olof
    KTH, School of Biotechnology (BIO), Bioprocess Technology.
    Process technology for production and recovery of heterologous proteins with Pichia pastoris2006In: Biotechnology progress (Print), ISSN 8756-7938, E-ISSN 1520-6033, Vol. 22, no 6, p. 1465-1473Article, review/survey (Refereed)
    Abstract [en]

    Developments in process techniques for production and recovery of heterologous proteins with Pichia pastoris are presented. Limitations for the standard techniques are described, and alternative techniques that solve the limitations problems are reviewed together with the methods that resulted in higher productivity of the P. pastoris processes. The main limitations are proteolysis of the secreted products and cell death in the high cell density bioreactor cultures. As a consequence, both low productivity and lower quality of the feedstock for downstream processing are achieved in processes hampered with these problems. Methods for exploring proteolysis and cell death are also presented. Solving the problems makes the conditions for downstream processing superior for the P. pastoris expression systems compared to other systems, which either need complex media or rely on intracellular production. These improved conditions allow for interfacing of cultivation with downstream processing in an integrated fashion.

  • 17. Komaraiah, P.
    et al.
    Navratil, M.
    Carlsson, Maria
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biotechnology .
    Jeffers, P.
    Ctr. for Synthesis and Chem. Biology, Department of Chemical Engineering, University College Dublin, Belfield, Dublin 4, Ireland.
    Brodelius, M.
    Dept. of Chem. and Biomed. Sciences, University of Kalmar, SE-391 82 Kalmar, Sweden.
    Brodelius, P.E.
    Dept. of Chem. and Biomed. Sciences, University of Kalmar, SE-391 82 Kalmar, Sweden.
    Kieran, P.M.
    Ctr. for Synthesis and Chem. Biology, Department of Chemical Engineering, University College Dublin, Belfield, Dublin 4, Ireland.
    Mandenius, Carl-Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biotechnology .
    Growth behavior in plant cell cultures based on emissions detected by a multisensor array2004In: Biotechnology progress (Print), ISSN 8756-7938, E-ISSN 1520-6033, Vol. 20, no 4, p. 1245-1250Article in journal (Refereed)
    Abstract [en]

    The use of a multisensor array based on chemical gas sensors to monitor plant cell cultures is described. The multisensor array, also referred to as an electronic nose, consisted of 19 different metal oxide semiconductor sensors and one carbon dioxide sensor. The device was used to continuously monitor the off-gas from two plant cell suspension cultures, Morinda citrifolia and Nicotiana tabacum, cultivated under batch conditions. By analyzing the multiarray responses using two pattern recognition methods, principal component analysis and artificial neural networks, it was possible to monitor the course of the cultivations and, in turn, to predict (1) the biomass concentration in both systems and (2) the formation of the secondary metabolite, antraquinone, by M. citrifolia. The results identify the multisensor array method as a potentially useful analytical tool for monitoring plant process variables that are otherwise difficult to analyze on-line.

  • 18.
    Komaraiah, Palle
    et al.
    St.Jude Children´s Reserarch Hospital.
    Navratil, Marian
    Linköpings universitet.
    Carlsson, Maria
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biotechnology.
    Jeffers, Paul
    University College Dublin.
    Brodelius, Maria
    University of Kalmar.
    Brodelius, Peter E.
    University of Kalmar.
    Kieran, Patricia M.
    University of Kalmar.
    Mandenius, Carl-Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biotechnology.
    Growth Behavior in Plant Cell Cultures Based on Emissions Detected by a Multisensor Array2004In: Biotechnology progress (Print), ISSN 8756-7938, E-ISSN 1520-6033, Vol. 20, p. 1245-1250Article in journal (Refereed)
  • 19.
    Malisauskas, Mantas
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Meskys, Rolandas
    Morozova-Roche, Ludmilla
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Ultrathin silver nanowires produced by amyloid biotemplating2008In: Biotechnology progress (Print), ISSN 8756-7938, E-ISSN 1520-6033, Vol. 24, no 5, p. 1166-1170Article in journal (Refereed)
    Abstract [en]

    By using a self-assembled amyloid from lysozyme as biotemplate we produced an ultrathin silver wire of 1 nm diameter and up to 2 μm in length, which is at the limit attainable in nanobiotechnological manufacturing. We showed that 2,2,2-trifluoroethanol produces a dual effect: it reduces ionic silver to colloidal nanoparticles with a regular size, depending on the length of incubation, and induces fibrillar assembly into the amyloid scaffold, forming the hollow channel filled with silver.

  • 20.
    Mandenius, C. F.
    et al.
    Dept. of Phys. and Msrmt. Technology, Linköping University.
    Lidén, H.
    Dept. of Phys. and Msrmt. Technology, Linköping University.
    Eklöv, T.
    Dept. of Phys. and Msrmt. Technology, Linköping University.
    Taherzadeh, Mohammad J
    Dept. of Chem. Reaction Engineering, Chalmers University of Technology.
    Lidén, G.
    Dept. of Chem. Reaction Engineering, Chalmers University of Technology.
    Predicting fermentability of wood hydrolyzates with responses from electronic noses1999In: Biotechnology progress (Print), ISSN 8756-7938, E-ISSN 1520-6033, Vol. 15, no 4, p. 617-621Article in journal (Refereed)
    Abstract [en]

    The fermentability of lignocellulose hydrolyzates have been predicted from the responses of a combination of chemical gas sensors. The hydrolyzates were prepared by dilute-acid hydrolysis of wood from pine, aspen, birch, and spruce. The volatile emission from the hydrolyzates before fermentation was measured, and the sensor array response pattern was compared with the observed fermentability of the hydrolyzates, i.e. with the final ethanol concentration after fermentation and the maximum specific ethanol production rate. Two concentration parameters in the hydrolyzates, furfural and the sum of furfural and 5-(hydroxymethyl)furfural (HMF), were also predicted from the responses. The sensors used were metal oxide semiconductor field effect transistors (MOSFET), tin oxide semiconductor devices, and conductive polymer sensors configured in two sensor arrays. The sensor array response pattern was analyzed by principal component analysis and artificial neural networks. Predictions from artificial neural networks deviated from measured values with less than 15%.The fermentability of lignocellulose hydrolyzates have been predicted from the responses of a combination of chemical gas sensors. The hydrolyzates were prepared by dilute-acid hydrolysis of wood from pine, aspen, birch, and spruce. The volatile emission from the hydrolyzates before fermentation was measured, and the sensor array response pattern was compared with the observed fermentability of the hydrolyzates, i.e. with the final ethanol concentration after fermentation and the maximum specific ethanol production rate. Two concentration parameters in the hydrolyzates, furfural and the sum of furfural and 5-(hydroxymethyl)furfural (HMF), were also predicted from the responses. The sensors used were metal oxide semiconductor field effect transistors (MOSFET), tin oxide semiconductor devices, and conductive polymer sensors configured in two sensor arrays. The sensor array response pattern was analyzed by principal component analysis and artificial neural networks. Predictions from artificial neural networks deviated from measured values with less than 15%.

  • 21.
    Mandenius, Carl-Fredrik
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biotechnology . Linköping University, The Institute of Technology.
    Brundin , Anders
    Linköping University, Department of Physics, Chemistry and Biology, Biotechnology . Linköping University, The Institute of Technology.
    Bioprocess Optimization Using Design-of-Experiments Methodology2008In: Biotechnology progress (Print), ISSN 8756-7938, E-ISSN 1520-6033, Vol. 24, no 6, p. 1191-1203Article, review/survey (Other academic)
    Abstract [en]

    This review surveys recent applications of design-of-experiments (DoE) methodology in the development of biotechnological processes. Methods such as factorial design, response surface methodology, and (DoE) provide powerful and efficient ways to optimize cultivations and other unit operations and procedures using a reduced number of experiments. The multitude of interdependent parameters involved within a unit operation or between units in a bioprocess sequence may be substantially refined and improved by the use of such methods. Other bioprocess-related applications include strain screening evaluation and cultivation media balancing. In view, of the emerging regulatory demands on pharmaceutical manufacturing processes, exemplified by the process analytical technology (PAT) initiative of the United States Food and Drug Administration, the use of experimental design approaches to improve process development for safer and more reproducible production is becoming increasingly important. Here, these options are highlighted and discussed with a few selected examples from antibiotic fermentation, expanded bed optimization, virus vector transfection of insect cell cultivation, feed profile adaptation, embryonic stem cell expansion protocols, and mammalian cell harvesting.

  • 22. Miranda, A.
    et al.
    Berglund, Kris
    Recovery of Clostridium thermosulfurogenes produced β-amylase by (hydroxypropyl)methylcellulose partition1990In: Biotechnology progress (Print), ISSN 8756-7938, E-ISSN 1520-6033, Vol. 6, no 3, p. 214-219Article in journal (Refereed)
    Abstract [en]

    A procedure for recovering Clostridium thermosulfurogenes produced β-amylase from fermentation broth by partition was developed. The partition was achieved by addition of ammonium sulfate to an aqueous solution of the enzyme with (hydroxypropyl)methylcellulose. The β-amylase-containing pellet formed upon centrifugation could be redissolved and the polymer recovered by a second salt addition. The process was not dependent on polymer/enzyme solution pH, but it was affected by temperature, polymer nominal molecular weight and loading, and fermentation carbon source. Unlike more traditional aqueous-phase partitions, such as poly(ethylene glycol)/dextran, the current approach appeared to be biospecific.

  • 23.
    Miranda, Everson A.
    et al.
    Michigan State University.
    Berglund, Kris
    Evaluation of column flotation in the downstream processing of fermentation products: recovery of a genetically engineered α-amylase1993In: Biotechnology progress (Print), ISSN 8756-7938, E-ISSN 1520-6033, Vol. 9, no 4, p. 411-420Article in journal (Refereed)
    Abstract [en]

    Flotation is a simple, inexpensive, and versatile unit operation with a largely unexplored potential in biotechnology. There is a general lack of research concerning biotechnological applications in this area, especially in the recovery of fermentation products. Moreover, the few reports in the literature do not consider the modern concept of column flotation as practiced in the mineral industry. We report herein the application of column flotation for the recovery of a Bacillus stearothermophilus α-amylase expressed in Escherichia coli by the use of a food-grade polymer, (hydroxypropyl)methylcellulose (HPMC), and ammonium sulfate. First, the enzyme was removed from the liquid phase by partition to a salted-out HPMC phase. The enzyme-containing polymer flocs were then floated from the liquid. Recovery of active enzyme was as high as 90%, with throughput as high as 94 m3/(h·m2). The floatability of the enzyme from a periplasmic extract was higher than extracellular enzyme in the broth due to the presence of depressors of molecular weight lower than 10 000 in the broth.

  • 24.
    Spens, Erika
    et al.
    KTH, School of Biotechnology (BIO).
    Häggström, Lena
    KTH, School of Biotechnology (BIO).
    Defined protein-free NS0 myeloma cell cultures: stimulation of proloferation by conditioned medium factors2005In: Biotechnology progress (Print), ISSN 8756-7938, E-ISSN 1520-6033, Vol. 21, no 1, p. 87-95Article in journal (Refereed)
    Abstract [en]

    A chemically defined, protein-free, and animal-component-free medium, designated RITM01, has been developed for NS0 myeloma cells. The basal medium used was a commercial serum-free and protein-free hybridoma medium, which was supplemented with phosphatidylcholine, cholesterol, β-cyclodextrin, and ferric citrate. Increasing the amino acid concentration significantly improved cell growth. An NS0 cell line, constitutively producing a human IgG1 antibody, reached a peak cell density of 3 × 106 cells mL -1 in this medium. The antibody yield was 195 mg L-1 in batch culture, which is a 3-fold increase compared to that of a standard serum-supplemented medium, even though the cell yield was the same. The increase in antibody yield was a consequence of a longer growth phase and a slight increase in specific antibody production rate at low specific proliferation rates. Adaptation of the NS0 myeloma cell line to the protein-free conditions required about 3 weeks before viability and cell densities were stabilized. Most probably, changes in gene expression and phenotypic behavior necessary for cell survival and proliferation occurred. We hypothesize that mitogenic factors produced by the cells themselves are involved in autocrine control of proliferation. To investigate the presence of such factors, the effect of conditioned (spent) medium (CM) on cell growth and proliferation was studied. Ten-fold concentrated CM, harvested at a cell density of 2 × 10 6 cells mL-1, had a clear positive effect on proliferation even if supplied at only 2.5% (v/v). CM was found to contain significant amounts of extracellular proteins other than the antibody. Fractionation of CM on a gel filtration column and subsequent supplementation of new NS0 cultures with the individual fractions showed that factors eluting at 20-25 kDa decreased the lag phase and increased the peak cell density as compared to control cultures. Identification of autocrine factors involved in regulation of proliferation may lead to completely new strategies for control of growth and product formation in animal cell processes.

  • 25. Zhang, Peng
    et al.
    Chen, Lin
    Zhang, Qingsong
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Hong, Feng F.
    Using in situ nanocellulose-coating technology based on dynamic bacterial cultures for upgrading conventional biomedical materials and reinforcing nanocellulose hydrogels2016In: Biotechnology progress (Print), ISSN 8756-7938, E-ISSN 1520-6033, Vol. 32, no 4, p. 1077-1084Article in journal (Refereed)
    Abstract [en]

    Bacterial nanocellulose (BNC) is a microbial nanofibrillar hydrogel with many potential applications. Its use is largely restricted by insufficient strength when in a highly swollen state and by inefficient production using static cultivation. In this study, an in situ nanocellulose-coating technology created a fabric-frame reinforced nanocomposite of BNC hydrogel with superior strength but retained BNC native attributes. By using the proposed technology, production time could be reduced from 10 to 3 days to obtain a desirable hydrogel sheet with approximately the same thickness. This novel technology is easier to scale up and is more suitable for industrial-scale manufacture. The mechanical properties (tensile strength, suture retention strength) and gel characteristics (water holding, absorption and wicking ability) of the fabric-reinforced BNC hydrogel were investigated and compared with those of ordinary BNC hydrogel sheets. The results reveal that the fabric-reinforced BNC hydrogel was equivalent with regard to gel characteristics, and exhibited a qualitative improvement with regard to its mechanical properties. For more advanced applications, coating technology via dynamic bacterial cultures could be used to upgrade conventional biomedical fabrics, i.e. medical cotton gauze or other mesh materials, with nanocellulose.

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