Showing papers on "Bioreactor published in 1985"

A microbial culture with oxygen‐sensitive product distribution as a potential tool for characterizing bioreactor oxygen transport

Abstract: The dissolved oxygen (DO) level has been shown to have a profound effect on the product distribution of a Bacillus subtilis culture, with acetoin being excreted with DO above 100 parts per billion (ppb) and butanediol below 100 ppb. The product concentration ratio changed rapidly in the 80–90 ppb range. Switching from one oxygen level to another caused one already accumulated product to be converted to the other in a reversible manner. Rates of change of 0.5–1 g/L h enabled detection within 10 min. Detection sensitivity is enhanced because the ratio of two concentrations can be measured. Remarkably sensitive to mixing rates, the culture responded to changes in stirring speed during experiments in which the dissolved oxygen was controlled at a constant level with a novel control system. Thus, the culture is capable of detecting dead zones in relatively well-mixed reactors and oxygen gradients in column and tubular reactors. High-viscosity effects can also be investigated since the culture grows well in xanthan gum solutions. Preliminary kinetic model development indicates that a useful model for simulating reactor mixing and transport effects can be developed to aid in the planning of experiments.

Dual aerobic hollow-fiber bioreactor for cultivation of Streptomyces aureofaciens.

Abstract: Streptomyces aureofaciens (ATCC 12416c) was grown in the interstitial region formed by a parallel arrangement of three hollow silicone tubules contained within a microporous polypropylene hollow fiber. Liquid-soluble nutrients were supplied by diffusion across the polypropylene fiber to the interstitial cell-containing region whereas air or oxygen was provided by diffusion from the silicone tubule lumina to the cell mass. In this bioreactor, S. aureofaciens grew to high cell densities (greater than 10(11) cells/cm(3)) and the culture so-obtained continously synthesized the secondary metabolite tetracycline. The volumetric productivity of tetracycline based on the interstitial volume was 90 microg/ml/h and based on the total reactor volume was 5.5 microg/mL/h. The high surface area-to-volume ratio afforded by the cylindrical configuration together with spatially distinct conduits to continuously transport liquids and gases, each of which may be nutrients or products of biosynthesis, to or from a tissuelike cell mass provides an alternative to the conventional air- or oxygen-sparged fermentation vessel. High volumetric reactor productivities may be achieved by virute of the concentrated stationary cell mass and by the appropriate selection of fiber sizes and materials so as to ensure adequate supplies of liquid and gaseous substrates to, as well as removal of metabolites from, most cells in the culture. This reactor topology is quite general and may be adapted to most microbial as well as mammalian and plant cell systems.

Production of citric acid by Aspergillus niger immobilized in polyacrylamide gels

Abstract: Living Aspergillus niger cells were entrapped in polyacrylamide gels and employed in both replacement batch and continuous column bioreactors to produce citric acid from sucrose. With the replacement batch bioreactor, increase of citric acid was observed under conditions of higher aeration and of wider surface of immobilized cells. With the continuous bioreactor, the maximum citric acid yield was 39.1 mg/h per 40 g gels. The biocatalyst activity or half-life was 105 days.

Comparisons between cellulase production by Aspergillus fumigatus in agitated vessels and in an air-lift fermentor.

Abstract: Aspergillus fumigatus was cultured in disc-turbine-agitated vessels and in an air-lift fermentor. In the agitated vessels the yield of cellulase was reduced when the agitation rate was increased, although extracellular protein levels rose. The enzyme complex itself was shown to be exceptionally stable under conditions similar to those in the agitated vessels, so probably shear damage to the mycelium had occurred, liberating intracellular contents. These appeared to contain an inhibitor that could be removed by fabricated inorganic protein absorbents, such as kieselguhr and alumina. However, the inhibitor was not likely to be protease, since only relatively low levels could be detected and its identity has not been established. The use of an air-lift fermentor avoided the shear effects due to use of the disc turbine agitator in the conventional fermentors, and yields of enzyme were then found to increase by about 20%, maximum yields being obtained at maximum KLa values.

Bioreactor for the study of defined interactions of toxic metals and biofilms.

Abstract: A novel bioreactor system constructed for studies of the interactions of heavy metals and microbial cells at the solid-solution interface is described. The applicability of this experimental system to meet the severe constraints imposed on such an apparatus by the requirements for an unambiguous interpretation of data and for mathematical modeling of these interactions was explored with the trace metal lead and with the marine bacterium Pseudomonas atlantica. A chemically defined medium composed of the major components of seawater, simple salts required for growth, glucose, and the single amino acid glycine was derived. It supported a maximum growth rate several times less than that in a complex medium, but provided growth to high cell densities and the formation of biopolymer and supported the development of a monolayer biofilm. The use of such a medium in conjunction with our bioreactor system minimized trace metal contamination while allowing quantification of the partitioning of lead onto various reactor surfaces. Lead adsorption by reactor walls and model surfaces was linear with equilibrium led concentration up to 6 X 10(-6) mol/liter. Equilibrium lead adsorption due to P. atlantica biofilm surfaces ranged from 20 to 40% at a total lead concentration of 10(-6) mol/liter depending upon solution pH and ionic composition, indicating that biofilms can play an important role in controlling toxic metal concentrations in natural systems.

Invited review on the use of chemically structured models for bioreactors

Abstract: An individual cell is an immensely complicated self-regulated chemical reactor that can alter its biosynthetic machinery to meet the demands of a changing environment. The biochemical engineer must...

Process for the continuous production of L-carnitine

Abstract: Process for the continuous production of L-carnitine by the microbiological method. A microorganism of the strain DSM No. 3225 (HK 1331b) type is cultivated in a bioreactor with crotonobetaine and/or γ-butyrobetaine in the presence of a growth substrate. The culture fluid passes outside of the bioreactor in a circulation in which a separation of the cell is carried out. A quantity of cell-free solution, which is as large as the amount fed to the bioreactor as a substrate, is withdrawn from the bioreactor. The L-carnitine is separated from the cell-free solution.

Production of high fructose syrup from jerusalem artichoke tubers using Kluyveromyces marxianus cells immobilized in agar gel.

Abstract: Hydrolysis of inulin from Jerusalem artichoke tuber extract by cells of the yeast Kluyveromyces marxianus immobilized in agar has been studied in batch and packed bed bioreactor systems. In a batch reactor using around 43 units of enzyme activity, about 94% hydrolysis of the total potential sugars was achieved in 10hr. The product consisted of about 90% fructose and 10% glucose. The same immobilized cells were used repeatedly for 9 cycles starting with fresh juice at the beginning of each cycle. The activity of the immobilized cells remained more or less constant during the first 5 cycles but beyond that it started to decrease. The maximum conversion rate obtained after 9 batch cycles was about 48% of the original. In column reactors, packed with 103 units of enzyme activity, the conversion rate remained almost constant at dilution rates lower than 0.34hr-1 but decreased beyond 0.34hr-1. The productivity at dilution rates D=1.1hr-1 and 0.61hr-1 was calculated to be 46g•l-1 hr-1 and 31g•l-1•hr-1 respectively and the corresponding conversion rates were 76 and 95%. Continuous operation of the column at a constant dilution rate of D=0.61hr-1 for 15 days at 45°C, resulted in 43% loss of the original activity. The half life of the bioreactor was estimated to be 17 days.

A novel bioreactor-cell precipitator combination for high-cell density, high-flow fermentations.

Abstract: A novel bioreactor design has been investigated for carrying out in a single unit a fermentation and cell recycle process simultaneously. The reactor consisted of a typical fermentor and a side-arm attached at a certain fixed angle to the fermentor. Due to the enhanced sedimentation in the inclined side-arm, the cells precipitate quickly and flow back into the fermentor. This allowed an essentially cell-free fermentation broth to be withdrawn at high rates through the sidearm while maintaining a high cell density culture in the fermentor. Continuous flow fermentation runs of S. cerevisiae demonstrated these features and showed that many fold increases in the steady-state cell density could be achieved using high flowrates, which in an ordinary chemostat would lead to washout. Ethanol productivities were high and can further be increased several-fold through a straightforward scale-up of the precipitator sidearm to sustain even larger flow rates. Discussed also are various other reactor features such as the enhanced resistance to contamination, possible reduction of the plasmid instability problems of recombinant microorganisms, potential applications with flocculent strains, steady-state coexistence of competing populations in mixed culture, and the possibility of carrying out fermentations with stationary cultures under continuous flow conditions.

Continuous bioreactor and process

Abstract: An improved bioreactor and process for continuously propagating microorganisms, such as yeast, wherein the culture medium is purified in contact with a spirally-wound ultrafiltration membrane and then passed through the outer surfaces of a tubular membrane material for further purification before contact with microorganisms flowing in the interior of the tubular membrane material.

A New Type of Bioreactor Employing Immobilized Yeast

Abstract: A new type of bioreactor that uses brewer's yeast strains immobilized in a calcium alginate gel has been developed. This bioreactor permits rapid batch production of beer or ale using any yeast str...

Continuous acidification of milk before ultrafiltration by an immobilized cell bioreactor. I. Development of the bioreactor

Abstract: Description et mise en oeuvre de deux types de bioreacteurs utilisant deux souches de Streptococcus lactis

Continuous acidification of milk before ultrafiltration by an immobilized cell bioreactor. II. Factors affecting the acid production of the bioreactor

Abstract: Definition des parametres technologiques et biologiques (Streptococcus lactis) permettant une acidification correcte sans floculation jusqu'a pH 6,2

Yeast cells entrapped in low-gelling temperature agarose for the continuous production of ethanol

Abstract: Continuous ethanol production byS.uvarum immobilized in a low-gelling temperature agarose namely SeaPlaque agarose was studied in a packed bed reactor at 30°C using sugarcane molasses containing 13.5% fermentable sugars as feed. The productivity at 95% conversion was 23 g/l.h (on reactor volume basis). The bioreactor was run continuously at a fixed dilution rate and it retained 60% of its initial activity upto 80 days.

Anaerobic treatment of concentrated industrial wastewater

Abstract: Test results are given for anaerobic digestion with the production of methane as a possible treatment for industrial landfill leachate. The study of volatile fatty acids during batch experiments provides several insights into the degradation of organic solutes in the complex wastewater used. A one tenth dilution of leachate led to a very slight lag period for the removal of acetate, propionate, and butyrate, with an unadapted culture of selected organisms. An overall dissolved organic carbon reduction of 61% was noted during a batch experiment using a leachate dilution of 5% and a culture adapted to leachate. The build-up of butyrate indicates a breakdown of other, larger organic species in the leachate. When a culture selected for volatile fatty acid degradation was used, this effect was not observed. Apparently the organisms responsible for the formation of butyrate from higher compounds are not present in this culture. Inhibition of methane occurs when the leachate adapted culture is dosed with leachate, presumably because of sulfate reducers. 9 references, 9 figures, 2 tables.

Membrane bioreactors for high-performance fermentations

Abstract: Avantages des bioreacteurs a membranes. Etude comparee du fermenteur a recirculation a membrane et du bioreacteur a fibres creuses

Continuous alcohol production from whey permeate using immobilised cell reactor systems

Abstract: The present paper reports the performance of a bioreactor packed with alginate-entrapped Kluyveromyces marxianus NCYC179 for continuous fermentation of whey permeate to ethanol. A maximum ethanol productivity as 28.21 gl−1 h−1 was attained at D=0.42h−1 and 75% lactose consumption (substrate feed rate in the inflowing medium was 200 g lactose I−1). However, the higher dilution rates (0.6-1.Oh−1) resulted in poor productivities and higher substrate washout in the effluent samples. The maximum specific ethanol production (qpi) and maximum specific lactose uptake (qsi) of the immobilised Kluyveromyces marxianus NCYC179 was found to be 3.88g ethanol/g immobilised cell/hx10−2 and 8.75g lactose consumed/g immobilised cell/hx10−2 respectively. A bead size of 2.5 mm in diameter and activation period of 24h of alginate beads in lactose solution (10%) prior to their packing in column reactor were found to support the efficient working of the bioreactor. The immobilised cell bioreactor system was operated continuously at a constant dilution rate of 0.15h−1 and 10% lactose for 562 h without any significant change in the efficiency (varied from 84 to 88% of theoretical) and viability of the entrapped yeast cells (dropped from 84 to 81%).

Reaction method using enzyme or microbial cell and immobilizing agent using therefor

Abstract: PURPOSE:To prevent the clogging of a reactor and the residence of the reaction liquid, and to improve the reaction efficiency remarkably, by carrying out the reaction of an enzyme or microbial cells in a bioreactor packed with an immobilized agent having a void ratio of >=70%. CONSTITUTION:A three-dimensional mat carrier composed of heat-resistant plastic fibers of 0.2-2mm. diameter wherein the cross-point of each fiber is fixed by bonding, is immersed in a mixed solution of a natural coagulant such as kappa-carrageenan, alginic acid salt, etc. and an enzyme or microbial cells, and is cooled and solidified to obtain an immobilized agent having a void ratio of >=70%. 2- 10 sheets of the carrier are placed in a reactor in a manner separated from each other by a straightener, metal mesh, or other supporting member 2. A gas diffuser 5 is placed at the bottom of the bioreactor to effect the supply of the gas necessary for the reaction and the mixing and stirring of the gas.

Growth kinetics of anaerobic bacteria during batch fermentation

Abstract: The kinetic characteristics of a batch methane fermentation system was examined using a glucose-based synthetic substrate. Conversion to methane was biphasic. The apparent growth yields of bacteria of the two phases were very different. Inoculum size and pH of the medium had a strong influence on the length of lag and the maximum methane production rate.

Method and apparatus for membrane-transmission fermentation or reaction

Abstract: PURPOSE:To obtain fermented liquid or reacted liquid in a short time, without causing adverse effect to the microbial cell, by passing the feed liquid for fermentation or reaction in one direction through a membrane or a tube prepared by mixing living microbial cell or enzyme with an immobilization carrier and a porous substance. CONSTITUTION:Living microbial cells or enzyme cultured in a culture liquid composed of glucose, peptone, yeast extract and water (e.g. Saccharomyces cerevisiae) are mixed with an immobilization carrier (e.g. K-carrageenan, aluminum alginate, etc.) and a porous substance (e.g. celite 545), and the mixture is formed to a membrane or a tube. The membrane, etc. is inserted between a pair of metal meshes having opening of about 1mm. and placed in a cylindrical bioreactor to obtain an immobilized yeast tank. The liquid for fermentation is sent from the feed tank 3 to the yeast tank under the nitrogen pressure of about 0.2kg/cm applied by the nitrogen bomb 2 via the pressure regulator 1, and passed through the yeast layer with a residence time of about 2hr to complete the fermentation. The obtained product (e.g. alcohol) and CO2 are taken out of the reactor through the bottom.

Preparation of hydrogen gas from organic waste water

Abstract: PURPOSE:To obtain a hydrogen gas efficiently, by fermenting organic waste water with an acid by a bioreactor to form lower fatty acids, hydrolyzing them with a photosynthetic bacterium under light irradiation. CONSTITUTION:First, organic waste water is fed to the acid-forming bioreactor 1 having the fixed bed 1a, it is fermented with an acid in the bioreactor 1, so that higher fatty acids such as saccharides, protein, etc. are hydrolyzed into lower fatty acids such as acetic acid, propionic acid, etc. Then, the hydrolyzed organic water water is fed to the gas preparation reactor 3. In the reactor 3, the organic waste water is agitated by the stirrer 4, it is irradiated with light rays from the light source 5 such as the sun, etc., and the organic waste water is decomposed with a photosynthetic bacterium, to give the desired hydrogen gas.