|
| ||
|
|
||
Bioreactor Design (bioreactor + design)
Selected AbstractsBioreactor for cultivation of red beet hairy roots and in situ recovery of primary and secondary metabolitesENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 3 2009Bhagyalakshmi Neelwarne Abstract To arrive at an appropriate bioreactor design and in situ recovery of the products, red beet hairy roots were used as a model system where the levels of betalain pigments (betacyanins and betaxanthins) were followed as secondary metabolite and the peroxidase enzyme as primary metabolite. Medium volume and other kinetic parameters were found to play significant roles by way of directly affecting the biomass yield rather than a specific metabolite. The hydrodynamic stress created on the roots by large culture volume could be minimized by pulse-feeding of medium in shake-flasks; and by separating the biomass chamber from the aerated medium reservoir in circulatory fed-batch bioreactor. Accordingly the bioreactor was modified to provide anchorage and air-enrichment chamber which resulted in higher formation of both the metabolites than in shake-flasks. Various down-stream processing aspects such as in situ release of pigments by non-destructive methods, followed by adsorption through a column and recovery by desorption were optimized for betalains. A strategy for simultaneous recovery of pigment and peroxidase was worked out using aqueous two phase extraction (ATPE). [source] Photosynthetic biomass and H2 production by green algae: from bioengineering to bioreactor scale-upPHYSIOLOGIA PLANTARUM, Issue 1 2007Ben Hankamer The development of clean borderless fuels is of vital importance to human and environmental health and global prosperity. Currently, fuels make up approximately 67% of the global energy market (total market = 15 TW year,1) (Hoffert et al. 1998). In contrast, global electricity demand accounts for only 33% (Hoffert et al. 1998). Yet, despite the importance of fuels, almost all CO2 free energy production systems under development are designed to drive electricity generation (e.g. clean-coal technology, nuclear, photovoltaic, wind, geothermal, wave and hydroelectric). In contrast, and indeed almost uniquely, biofuels also target the much larger fuel market and so in the future will play an increasingly important role in maintaining energy security (Lal 2005). Currently, the main biofuels that are at varying stages of development include bio-ethanol, liquid carbohydrates [e.g. biodiesel or biomass to liquid (BTL) products], biomethane and bio-H2. This review is focused on placing bio-H2 production processes into the context of the current biofuels market and summarizing advances made both at the level of bioengineering and bioreactor design. [source] A microfluidic bioreactor with integrated transepithelial electrical resistance (TEER) measurement electrodes for evaluation of renal epithelial cellsBIOTECHNOLOGY & BIOENGINEERING, Issue 4 2010Nicholas Ferrell Abstract We have developed a bilayer microfluidic system with integrated transepithelial electrical resistance (TEER) measurement electrodes to evaluate kidney epithelial cells under physiologically relevant fluid flow conditions. The bioreactor consists of apical and basolateral fluidic chambers connected via a transparent microporous membrane. The top chamber contains microfluidic channels to perfuse the apical surface of the cells. The bottom chamber acts as a reservoir for transport across the cell layer and provides support for the membrane. TEER electrodes were integrated into the device to monitor cell growth and evaluate cell,cell tight junction integrity. Immunofluorescence staining was performed within the microchannels for ZO-1 tight junction protein and acetylated ,-tubulin (primary cilia) using human renal epithelial cells (HREC) and MDCK cells. HREC were stained for cytoskeletal F-actin and exhibited disassembly of cytosolic F-actin stress fibers when exposed to shear stress. TEER was monitored over time under normal culture conditions and after disruption of the tight junctions using low Ca2+ medium. The transport rate of a fluorescently labeled tracer molecule (FITC-inulin) was measured before and after Ca2+ switch and a decrease in TEER corresponded with a large increase in paracellular inulin transport. This bioreactor design provides an instrumented platform with physiologically meaningful flow conditions to study various epithelial cell transport processes. Biotechnol. Bioeng. 2010;107:707,716. © 2010 Wiley Periodicals, Inc. [source] The effect of carbon source on microbial community structure and Cr(VI) reduction rateBIOTECHNOLOGY & BIOENGINEERING, Issue 3 2010Athanasia G. Tekerlekopoulou Abstract In the present work, the effect of the carbon source on microbial community structure in batch cultures derived from industrial sludge and hexavalent chromium reduction was studied. Experiments in aerobic batch reactors were carried out by amending industrial sludge with two different carbon sources: sodium acetate and sucrose. In each of the experiments performed, four different initial Cr(VI) concentrations of: 6, 13, 30 and 115,mg/L were tested. The change of carbon source in the batch reactor from sodium acetate to sucrose led to a 1.3,2.1 fold increase in chromium reduction rate and to a 5- to 9.5-fold increase in biomass. Analysis of the microbial structure in the batch reactor showed that the dominant communities were bacterial species (Acinetobacter lwoffii, Defluvibacter lusatiensis, Pseudoxanthomonas japonensis, Mesorhizium chacoense, and Flavobacterium suncheonense) when sodium acetate was used as carbon source and fungal strains (Trichoderma viride and Pichia jadinii), when sodium acetate was replaced by sucrose. These results indicate that the carbon source is a key parameter for microbial dynamics and enhanced chromium reduction and should be taken into account for efficient bioreactor design. Biotechnol. Bioeng. 2010;107: 478,487. © 2010 Wiley Periodicals, Inc. [source] Role of nutrient supply on cell growth in bioreactor design for tissue engineering of hematopoietic cellsBIOTECHNOLOGY & BIOENGINEERING, Issue 7 2005Pragyansri Pathi Abstract In the present study, a dynamic mathematical model for the growth of granulocyte progenitor cells in the hematopoietic process is developed based on the principles of diffusion and chemical reaction. This model simulates granulocyte progenitor cell growth and oxygen consumption in a three-dimensional (3-D) perfusion bioreactor. Material balances on cells are coupled to the nutrient balances in 3-D matrices to determine the effects of transport limitations on cell growth. The method of volume averaging is used to formulate the material balances for the cells and the nutrients in the porous matrix containing the cells. All model parameters are obtained from the literature. The maximum cell volume fraction reached when oxygen is depleted in the cell layer at 15 days and is nearly 0.63, corresponding to a cell density of 2.25 × 108 cells/mL. The substrate inhibition kinetics for cell growth lead to complex effects with respect to the roles of oxygen concentration and supply by convection and diffusion on cell growth. Variation in the height of the liquid layer above the cell matrix where nutrient supply is introduced affected the relative and absolute amounts of oxygen supply by hydrodynamic flow and by diffusion across a gas permeable FEP membrane. Mass transfer restrictions of the FEP membrane are considerable, and the supply of oxygen by convection is essential to achieve higher levels of cell growth. A maximum growth rate occurs at a specific flow rate. For flow rates higher than this optimal, the high oxygen concentration led to growth inhibition and for lower flow rates growth limitations occur due to insufficient oxygen supply. Because of the nonlinear effects of the autocatalytic substrate inhibition growth kinetics coupled to the convective transport, the rate of growth at this optimal flow rate is higher than that in a corresponding well-mixed reactor where oxygen concentration is set at the maximum indicated by the inhibitory kinetics. ©2005 Wiley Periodicals, Inc. [source] A noninvasive technique for the measurement of the energetic state of free-suspension mammalian cellsBIOTECHNOLOGY PROGRESS, Issue 2 2010M. Ben-Tchavtchavadze Abstract A perfusion small-scale bioreactor allowing on-line monitoring of the cell energetic state was developed for free-suspension mammalian cells. The bioreactor was designed to perform in vivo nuclear magnetic resonance (NMR) spectroscopy, which is a noninvasive and nondestructive method that permits the monitoring of intracellular nutrient concentrations, metabolic precursors and intermediates, as well as metabolites and energy shuttles, such as ATP, ADP, and NADPH. The bioreactor was made of a 10-mm NMR tube following a fluidized bed design. Perfusion flow rate allowing for adequate oxygen supply was found to be above 0.79 mL min,1 for high-density cell suspensions (108 cells). Chinese hamster ovary (CHO) cells were studied here as model system. Hydrodynamic studies using coloration/decoloration and residence time distribution measurements were realized to perfect bioreactor design as well as to determine operating conditions bestowing adequate homogeneous mixing and cell retention in the NMR reading zone. In vivo 31P NMR was performed and demonstrated the small-scale bioreactor platform ability to monitor the cell physiological behavior for 30-min experiments. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source] Windows of operation for bioreactor design for the controlled formation of tissue-engineered arteriesBIOTECHNOLOGY PROGRESS, Issue 3 2009Spyridon Gerontas Abstract The availability of large numbers of units of artificial arteries would offer significant benefits to the clinical management of bypass surgery. Tissue engineering offers the potential of providing vessels that can mimic the morphology, function, and physiological environment of native vessels. Ideally this would involve culturing stem cells in vitro within a biodegradable tubular scaffold so as to construct tissue for implantation. Essential to establishing a robust process for the production of tissue-engineered arteries is the understanding of the impact of changes in the operating conditions and bioreactor design on the construct formation. In this article, models of transport phenomena were developed to predict the critical flow rates and mass transfer requirements of a prototype bioreactor for the formation of tissue-engineered arteries. The impact of the cell concentration, tube geometry, oxygen effective diffusivity in alginate, substrate and metabolite concentration levels, feed rate, and recycle rate on the design of the bioreactor was visualized using windows of operation and contour plots. The result of this analysis determined the best configuration of the bioreactor that meets the cellular transport requirements as well as being reliable in performance while seeking to reduce the amount of nutrients to be used. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] | ||||||||||