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PubMed1990

The synthesis of L-tryptophan degrading bioreactors.

To design a bioreactor for removing the potential cancer nutrient L-tryptophan from blood, the L-tryptophan degrading enzyme tryptophan side chain oxidase (TSO) was chemically bound to glutaraldehyde activated gamma amino silane silica and to Zetaffinity microcolumns consisting of a glutaraldehyde activated polyacrylic-cellulose copolymer. Five experiments were carried out in sheep and six experiments in rabbits using a closed circuit plasmapheresis bioreactor system. L-tryptophan in sheep was degraded by the silica bioreactor in a single pass to undetectable levels as measured by high performance liquid chromatography (HPLC). Zetaffinity bioreactors degraded L-tryptophan in rabbits to more than 95% in a single pass. Whole blood L-tryptophan levels changed little throughout the experiment indicating a vast extravascular tryptophan pool. Enzyme leakage from the bioreactor was less than 10(-5) IU TSO per ml plasma. The procedures were tolerated well by the animals without any change in vital signs.

Animals↗
PubMed1989

Monoclonal antibody production in hollow fiber bioreactors using serum-free medium.

Murine hybridoma cells that produce monoclonal antibody directed against human fibronectin have been cultured in VITAFIBER II and VITAFIBER V hollow fiber bioreactors using defined, serum-free WRC 935 medium. During a two-week growth period, following inoculation of the bioreactors, the cells proliferated to an extent where the bioreactor was filled with cultured cells. Using a 5 sq. ft. VITAFIBER V bioreactor, over 15 grams of antibody were produced during the 40 days of the experiment. This antibody was greater than 95% IgG. During the production period, this packed mass of cells produced 579 +/- 15 mg IgG per day. Because the medium is formulated for air equilibration and high cell densities, WRC 935 medium is especially useful for production of gram quantities of monoclonal antibodies using continuous feed hollow fiber bioreactor cell culture systems.

Animals↗
PubMed2025

Unraveling the ecological success of Iodidimonas in a bioreactor treating oil and gas produced water.

UNLABELLED: Iodidimonas sp., a bacterium found in bioreactors treating oil and gas produced water as well as iodide-rich brines, has garnered attention for its unique ability to oxidize iodine. However, little is known about the metabolic capabilities that enable Iodidimonas sp. to thrive in certain unique ecological niches. In this study, we isolated, characterized, and sequenced three strains belonging to the Iodidimonas genus from the sludge of a membrane bioreactor used for produced water treatment. We investigated the genomic features of these isolates and compared them with the four publicly available isolate genomes from this genus, as well as a metagenome-assembled genome from the source bioreactor. Our Iodidimonas isolates had several genes associated with mitigating salinity, heavy metal, and organic compound stress, which likely help these bacteria to survive in produced water. Phenotyping tests revealed that while the isolates could utilize a wide variety of simple carbon substrates, they failed to degrade aliphatic or aromatic hydrocarbons, consistent with the lack of genes associated with common hydrocarbon degradation pathways in their genomes. We hypothesize that these microbes may lead a scavenging lifestyle in the bioreactor and similar iodide-rich brines. IMPORTANCE: Occupying a niche habitat and having few representative isolates, the genus Iodidimonas is a relatively understudied alphaproteobacterial group. Its ability to corrode pipes in iodine production facilities has economic implications, and its ability to generate potentially carcinogenic iodinated organic compounds during treatment of oil and gas produced water may cause environmental and health concerns with the recycling of treated water. Therefore, detailed characterization of the metabolic potential of the Iodidimonas isolates in this study both sheds light on their adaptation to the environmental conditions they inhabit and has environmental and economic significance.

Bioreactors↗
PubMed1998

Effects of methocel A15LV, polyethylene glycol, and polyvinyl alcohol on CD13 and CD33 receptor surface content and metabolism of HL60 cells cultured in stirred tank bioreactors.

Flow cytometry was used to examine the effect of hydrodynamic forces in a stirred tank bioreactor on the CD13 and CD33 receptor surface content of HL60 (human promyelocytic leukemia) cells. A step increase in agitation rate from 80 to 400 rpm reduced the HL60 cell apparent growth rate and increased the CD13 receptor surface content per cell, on average, by 95%. In contrast, this step increase in agitation rate to 400 rpm decreased the CD33 receptor surface content per cell, on average, by 10%. The protective effects of 0.1% Methocel A15LV, polyethylene glycol (PEG), and polyvinyl alcohol (PVA) on CD13 and CD33 receptor surface content were examined under agitation at 300 rpm in parallel 2 L bioreactor runs. The average CD33 receptor surface content was unaffected by the presence of Methocel A15LV or PEG, while PVA had a slight protective effect. In contrast, in terms of CD13 receptor content, HL60 cells agitated at 300 rpm with Methocel A15LV, PEG, or PVA behaved like cells agitated at 80 rpm with no media additives (McDowell and Papoutsakis, 1998). That is, Methocel A15LV, PEG, and PVA prevented the transduction of mechanical forces which affect CD13 cell content. HL60 cells cultured with 0.1% A15LV, PEG or PVA under conditions of mild agitation (60 rpm) in spinner flasks exhibited glucose consumption and lactate production rates that were approximately 20% lower than values of cultures containing no additive. Under conditions of agitation at 300 rpm in the 2 L bioreactor, the presence of A15LV, PEG, and PVA reduced the HL60 glucose consumption and lactate production rates by approximately 50%. Thus, media additives can dramatically reduce lactate accumulation in agitated bioreactors due to cell growth, in addition to providing protection from cellular injury.

Antigens, CD↗
PubMed2000

Dynamic modeling and optimal fed-batch feeding strategies for a two-phase partitioning bioreactor.

A dynamic model for the degradation of phenol in a two-phase partitioning bioreactor has been developed based on mechanistic balances around the bioreactor. The key process characteristics including substrate transfer between the organic and aqueous phases, substrate inhibition, oxygen limitation, and cell entrainment were incorporated into the model. The model predictions were validated against existing experimental data obtained for a 2-L bioreactor, and good correlation was observed for the time frames of the simulations, as well as for trends in cell and substrate concentrations. Optimal fed-batch, phenol feeding strategies were then developed based on two approaches: (1) maximization of phenol consumption in a fixed time interval and (2) consumption of a fixed amount of phenol in minimal time. The optimal feeding policies, determined using the Iterative Dynamic Programming algorithm, provided substantial improvements in the amount of phenol consumed when compared to a typical experimental heuristic approach. For example, 45.73 g of phenol was predicted to be consumed in 50 h (not including lag phase) using the optimal feeding profile compared to 10.26 g of phenol consumed in the simulated experimental approach. Oxygen limitation was predicted to be a recurring operational challenge in the partitioning bioreactor, and had a strong impact on the optimization results.

Algorithms↗
PubMed2000

Contamination of a high-cell-density continuous bioreactor.

Continuous fermentations were carried out with a recombinant flocculent Saccharomyces cerevisiae strain in an airlift bioreactor. Once operating under steady state at a dilution rate of 0.45 h(-1), the bioreactor was contaminated with Escherichia coli cells. The faster growing E. coli strain was washed out of the bioreactor and the recombinant, slower growing flocculating S. cerevisiae strain remained as the only species detected in the bioreactor. Flocculation, besides allowing for the realization of high-cell-density systems with corresponding unusual high productivity, may be used as a selective property for controlling some contamination problems associated with prolonged continuous operation.

Bioreactors↗
PubMed2000

Effective production of a thermostable alpha-glucosidase from Sulfolobus solfataricus in Escherichia coli exploiting a microfiltration bioreactor.

A microfiltration (MF) membrane bioreactor was developed for an efficient production of a recombinant thermostable alpha-glucosidase (rSsGA) from Sulfolobus solfataricus MT-4. The aim of the membrane bioreactor was to improve the control of the concentration of key components in the growth of genetic engineered microorganisms, such as Escherichia coli. The influence of medium composition was studied in relation to cell growth and alpha-glucosidase production. The addition of components such as yeast extract and tryptone resulted in a higher enzyme production. High cell density cultivation of E. coli BL21(DE3) on semidefined medium, exploiting a microfiltration bioreactor, was studied in order to optimize rSsGA production. In addition to medium composition, the inducer employed (either isopropyl beta-D-thiogalactopyranoside or lactose), the induction duration, and the cultivation mode influenced both the final biomass and the enzyme yield. The MF bioreactor allowed a cell concentration of 50 g/L dry weight and a corresponding alpha-glucosidase production of 11,500 U/L. The improvement obtained in the enzyme production combining genetic engineering and the microfiltration strategy was estimated to be 2,000-fold the wild-type strain.

Bioreactors↗
PubMed2001

Removal of toluene in a vapor-phase bioreactor containing a strain of the dimorphic black yeast Exophiala lecanii-corni.

Stricter regulations on volatile organic compounds and hazardous air pollutants have increased the demand for abatement technologies. Biofiltration, a process in which contaminated air is passed through a biologically active bed, can be used to remove these pollutants from air streams. In this study, a fungal vapor-phase bioreactor containing a strain of the dimorphic black yeast, Exophiala lecanii-corni, was used to treat a gas stream contaminated with toluene. The maximum toluene elimination capacity in short-term tests was 270 g m(-3) h(-1), which is 2 to 7 times greater than the toluene elimination capacities typically reported for bacterial systems. The fungal bioreactor also maintained toluene removal efficiencies of greater than 95% throughout the 175-day study. Harsh operating conditions such as low moisture content, acidic biofilms, and nitrogen limitation did not adversely affect performance. The fungal bioreactor also rapidly reestablished high toluene removal efficiencies after an 8-day shutdown period. These results indicate that fungal bioreactors may be an effective alternative to conventional abatement technologies for treating high concentrations of pollutants in waste gas streams.

Air Pollutants↗
PubMed2002

Erythropoietin production from CHO cells grown by continuous culture in a fluidized-bed bioreactor.

A Chinese hamster ovary (CHO) cell line that expresses human erythropoietin (huEPO) was in a 2-L Cytopilot fluidized-bed bioreactor with 400 mL macroporous Cytoline-1 microcarriers and a variable perfusion rate of serum-free and protein-free medium for 48 days. The cell density increased to a maximum of 23 x 10(6) cells/mL, beads on day 27. The EPO concentration increased to 600 U/mL during the early part of the culture period (on day 24) and increased further to 980 U/mL following the addition of a higher concentration of glucose and the addition of sodium butyrate. The EPO concentration was significantly higher (at least 2x than that in a controlled stirred-tank bioreactor, in a spinner flask, or in a stationary T-flask culture. The EPO accumulated to a total production of 28,000 kUnits over the whole culture period. The molecular characteristics of EPO with respect to size and pattern of glycosylation did not change with scale up. The pattern of utilization and production of 18 amino acids was similar in the Cytopilot culture to that in a stationary batch culture in a T-flask. The concentration of ammonia was maintained at a low level (< 2 mM) over the entire culture period. The specific rate of consumption of glucose, as well as the specific rates of production of lactate and ammonia, were constant throughout the culture period indicating a consistent metabolic behavior of the cells in the bioreactor. These results indicate the potential of the Cytopilot bioreactor culture system for the continuous production of a recombinant protein over several weeks.

Amino Acids↗
PubMed2004

Fluid mechanics of a spinner-flask bioreactor.

Spinner-flask bioreactors have been used for the production of articular cartilage in vitro. The dynamic environment within bioreactors is known to significantly affect the growth and development of the tissue. The present research focuses on the experimental and numerical characterization of the flow field within a spinner flask operating under conditions used to produce cartilage. Laboratory experiments carried out in a scaled-up model bioreactor employ particle-image velocimetry (PIV) to determine velocity and shear-rate fields in the vicinity of the construct closest to the stir bar, in addition to turbulence properties. Numerical computations calculated using FLUENT, a commercial software package, simulate the flow field in the same model bioreactor under similar operating conditions. In the computations, scaffolds were modeled as both solid and porous media with different permeabilities and flow rates through various faces of the construct nearest the stir bar were examined.

Bioreactors↗
PubMed2001

Longterm stability of phase I and phase II enzymes of porcine liver cells in flat membrane bioreactors.

Recently, researchers have focused on the use of bioartificial liver devices to support patients with fulminant hepatic failure. Our team developed a cell-based flat membrane bioreactor (FMB). In this, porcine liver cells were maintained in 3D-coculture between two gel layers in a sandwich configuration for 3 weeks to study the influence of this bioreactor technique on the preservation of basic, not induced activities of phase I and phase II enzymes. First, the time and substrate dependencies of the following enzymes were measured: ethoxyresorufin-O-deethylase (EROD, CYP 1A1/1A2) and ethoxycoumarin-O-deethylase (ECOD, CYP 2B6) as phase I enzymes, and glutathione-S-transferase (GST), UDP-glucuronosyltransferase (UGT) and sulfotransferase (ST) as phase II enzymes. To find optimal test conditions Michaelis-Menten kinetics were calculated. Next, different potential inducers were tested to find out the most effective compounds. Based on these results, the basic, not induced levels of the different enzymes were determined in the flat membrane bioreactor. Furthermore, the response of these enzyme activities to the chosen inducers was investigated to examine whether the cells keep their ability for drug-drug interactions. Basic, not induced activities of both phase I enzymes and the phase II enzymes GST and UGT were maintained at nearly the initial levels during the complete period of study. In addition, it was possible to induce these enzymes twice or three times in a weekly interval. In contrast, the basic, not induced activity of ST increased during the first 10 days of culture. It stabilized then and was maintained steady. As in short-term investigations, no reaction of the ST-activity towards any inducer could be obtained. These results prove that porcine liver cells preserve their phase I and phase II activities and respond to inducing drugs over 3 weeks in culture. Therefore, the flat membrane bioreactor is not only suitable for investigating drug metabolism, drug-drug interactions, and enzyme induction but also for supporting liver functions.

7-Alkoxycoumarin O-Dealkylase↗
PubMed2005

Relationships between hydrodynamics and rheology of flocculating yeast suspensions in a high-cell-density airlift bioreactor.

In this article a hydrodynamic and rheological analysis of a continuous airlift bioreactor with high-cell-density system is presented. A highly flocculating recombinant strain of Sacharomyces cerevisiae containing genes for lactose transport (lactose permease) and hydrolysis (beta-galactosidase) was exploited to ferment lactose from cheese whey to ethanol. The magnetic particle-tracer method was used to assess the effect of operational conditions (air-flow rate, biomass concentration) on hydrodynamic behavior of an airlift bioreactor during the fermentation process. Measurements of liquid circulation velocity showed the existence of a critical value of biomass concentration at which a dramatic deceleration of net liquid flow appeared with increasing biomass quantity. Rheological analysis revealed exponential increase of viscosity of the yeast floc suspension at the same biomass concentration of about 73 g/dm3 corresponding to 42.8% v/v of solid fraction. These facts have a particular importance for the successful processing of a high-cell-density airlift bioreactor as only a circulated flow regime will be favorable to keep the solid particles in suspension state and evenly distributed throughout the bioreactor.

Bioreactors↗
PubMed2006

Potential application of monolith packed columns as bioreactors, control of biofilm formation.

Monolith reactors combine good mass transfer characteristics with low-pressure drop, the principle factors affecting the cost effectiveness of industrial processes. Recently, these specific features of the monolith reactors have drawn the attention toward the application of the monolith reactor in multiphase reaction systems. In this study, we explore the potential application of monolith reactors as bioreactor requiring gas-liquid mass transfer for substrate supply. It is demonstrated on theoretical grounds that the monolith reactor is a competitive alternative to conventional gas-liquid bioreactors such as stirred tanks, packed beds, and airlift bioreactors because it allows for a significant reduction of the energy dissipation that is normally required for gas-liquid contacting. A potential problem of monolith reactors for biological processes is clogging due to biofilm formation. This paper presents experimental results of a study into the formation and possible removal of biofilms during operation of a monolith reactor as suspended cells bioreactor. The results indicate that biofilm formation may be minimized and postponed by a proper choice of operating conditions. Periodic biofilm removal could straightforwardly be achieved by rinsing with water at moderate pressures and allows for stable operation for prolonged periods of time.

Biofilms↗
PubMed2006

Characterization of an experimental miniature bioreactor for cellular perturbation studies.

A mini bioreactor (3.0 mL volume) has been developed and shown to be a versatile tool for rapidly screening and quantifying the response of organisms on environmental perturbations. The mini bioreactor is essentially a plug flow device transformed into a well-mixed reactor by a recycle flow of the broth. The gas and liquid phases are separated by a silicone membrane. Dynamic mass transfer experiments were performed to determine the mass transfer capacities for oxygen and carbon dioxide. The mass transfer coefficients for oxygen and carbon dioxide were found to be 1.55 +/- 0.17 x 10(-5) m/s and 4.52 +/- 0.60 x 10(-6) m/s, respectively. Cultivation experiments with the 3.0 mL bioreactor show that (i) it can maintain biomass in the same physiological state as the 4.0 L lab scale bioreactor, (ii) reproducible perturbation experiments such as changing substrate uptake rate can be readily performed and the physiological response monitored quantitatively in terms of the O2 and CO2 uptake and production rates.

Biodegradation, Environmental↗
PubMed2006

Online measurement of oxygen consumption by goat bone marrow stromal cells in a combined cell-seeding and proliferation perfusion bioreactor.

In an effort to produce clinically useful volumes of tissue engineered bone products, a direct perfusion bioreactor system was developed. Perfusion flow rate, flow direction, and the position of the bioreactor are factors that influenced the amounts and homogeneity of the cells seeded on the scaffold surface. Goat bone marrow stromal cells (GBMSCs) were dynamically seeded and proliferated in this system in relevant volumes (10 cm(3)) of small-sized macroporous biphasic calcium phosphate (BCP) scaffolds (2-6 mm). Cell load and cell distribution were shown using Methylene Blue block staining, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) staining was used to demonstrate the viability of the cells. Although cells were not distributed homogenously after cell seeding, the scaffolds were covered with a viable, homogeneous cell layer after 25 days of cultivation. The hybrid structures became interconnected, and a dense layer of extracellular matrix formed on and in the scaffolds. Online oxygen measurements during cultivation were correlated with proliferating GBMSCs. It was shown that the oxygen consumption could possibly be used to estimate GBMSC population doubling times during growth in this bioreactor system. On the basis of our results, we conclude that a direct perfusion bioreactor system is capable of seeding and proliferating GBMSCs on BCP ceramic scaffolds that can be monitored online during cultivation.

Animals↗
PubMed2004

Cartilage tissue engineering on the surface of a novel gelatin-calcium-phosphate biphasic scaffold in a double-chamber bioreactor.

Tissue engineering is a new approach to articular cartilage repair; however, the integration of the engineered cartilage into the host subchondral bone is a major problem in osteochondral injury. The aim of the present work, therefore, was to make a tissue-engineered osteochondral construct from a novel biphasic scaffold in a newly designed double-chamber bioreactor. This bioreactor was designed to coculture chondrocytes and osteoblasts simultaneously. The aim of this study was to prove that engineered cartilage could be formed with the use of this biphasic scaffold. The scaffold was constructed from gelatin and a calcium-phosphate block made from calcined bovine bone. The cartilage part of the scaffold had a uniform pore size of about 180 microm and approximate porosity of 75%, with the trabecular pattern preserved in the bony part of the scaffold. The biphasic scaffolds were seeded with porcine chondrocytes and cultured in a double-chamber bioreactor for 2 or 4 weeks. The chondrocytes were homogeneously distributed in the gelatin part of the scaffold, and secretion of the extracellular matrix was demonstrated histologically. The chondrocytes retained their phenotype after 4 weeks of culture, as proven immunohistochemically. After 4 weeks of culture, hyaline-like cartilage with lacuna formation could be clearly seen in the gelatin scaffold on the surface of the calcium phosphate. The results show that this biphasic scaffold can support cartilage formation on a calcium-phosphate surface in a double-chamber bioreactor, and it seems reasonable to suggest that there is potential for further application in osteochondral tissue engineering.

Animals↗
PubMed2004

Gluconic acid production in bioreactor with immobilized glucose oxidase plus catalase on polymer membrane adjacent to anion-exchange membrane.

Gluconic acid was obtained in the permeate side of the bioreactor with glucose oxidase (GOD) immobilized onto anion-exchange membrane (AEM) of low-density polyethylene grafted with 4-vinylpiridine. The electric resistance of the anion-exchange membranes was increased after the enzyme immobilization on the membrane. The gluconic acid productions were relatively low with the GOD immobilized by any method on the AEM. To increase the enzyme reaction efficiency, GOD was immobilized on membrane of AN copolymer (PAN) adjacent to an anion-exchange membrane in bioreactor. Uses of anion-exchange membrane led to selective removal of the gluconic acid from the glucose solution and reduce the gluconic acid inhibition. The amount of gluconic acid obtained in the permeate side of the bioreactor with the GOD immobilized on the PAN membrane adjacent to the AEM under electrodialysis was about 30 times higher than that obtained with enzyme directly bound to the AEM. The optimal substrate concentration in the feed side was found to be about 1 g/l. Further experiments were carried out with the co-immobilized GOD plus Catalase (CAT) on the PAN membrane adjacent to the AEM to improve the efficiency of the immobilize system. The yield of this process was at least 95%. The storage stability of the co-immobilized GOD and CAT was studied (lost 20% of initial activity for 90 d). The results obtained clearly showed the higher potential of the dual membrane bioreactor with GOD plus CAT bound to ultrafiltration polymer membrane adjacent to the AEM. Storage stability of GOD activity in GOD plus CAT immobilized on PAN//AEM membranes and on AEM.

Acetobacter↗
PubMed2002

Dynamic bioreactor operation: Effects of packing material and mite predation on toluene removal from off-gas.

Recent studies have focused on using vapor-phase bioreactors for the treatment of volatile organic compounds from contaminated air streams. Although high removal capacities have been achieved in many studies, long-term operation is often unstable at high pollutant loadings due to biomass accumulation and drying of the packing medium. In this study, three bench-scale bioreactors were operated to determine the effect of packing material and fungal predation on toluene removal efficiency and pressure drop. Toluene elimination capacities (mass toluene removed per unit packing per unit time) above 100 g m(-3) h(-1) were obtained in the fungal bioreactors packed with light-weight, artificial medium, and submersion of the packing in mineral medium once per week was found to provide sufficient moisture and nutrients to the biofilm. The use of mites as fungal predators improved performance by increasing the overall mineralization of toluene to CO(2), and by dislodging biomass along the bioreactor.

Air Pollutants↗