bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effects of limiting nutrients, dilution rate, culture pH, and temperature on the yield constant and anthocyanin accumulation of carrot cells grown in semicontinuous chemostat cultures
Authors: Dougall D. K. , LaBrake S. , Whitten G. H. 
Published: December 2004

AbstractWith carrot cells grown in semicontinuous culture with phosphate as limiting nutrient. Dougall and Weyrauch (1980) found that the steady‐state culture density was different at different dilution rates. They suggested that the yield constant for biomass was different at different dilution rates. Here the yield constant for biomass for PO, NH, Mg2+, and glucose‐limited semicontinuous cultures has been measured directly at two dilution rates. The yield constants for PO, NH4+, and Mg2+ but not for glucose are different at the two dilution rates. The effects of pH and temperature on the biomass yield constant was measured to extend the number of system parameters examined. Biomass yield constant was changed little with change from 25 to 28°C or from pH 4.2 to pH 5.5. The steady‐state levels of anthocyanin were also measured. The responses of anthocyanin levels to the system parameters are different to the biomass responses. The data suggest that at different values of each of the system parameters, the composition and metabolic activities of the cells at steady state in semicontinuous cultures are different.
Production of microbial biomass on the products of mild acid hydrolysis of piggery slurry
Authors: Davey G. , Bruce J. 
Published: December 2004

AbstractThe effect of mild sulfuric acid (H2SO4) hydrolysis on the cellulosic components of piggery slurry was investigated. Combinations of acid concentrations between 1 and 10% (w/v) and temperatures of 89, 90, and 100°C were studied with the aim of maximizing the release of soluble carbohydrates from the cellulosic constituents of piggery slurry. The highest yield of soluble monosaccharides was obtained by hydrolysis with 5% sulfuric acid at 90°C for 3 h, which produced 0.53 g of monosaccharide for every gram of cellulosic material available in raw piggery slurry. When the fungus Sporotrichum pulverulentum was cultivated on a medium prepared from this hydrolysate, a yield of 19.8 g of microbial biomass was obtained for each liter of piggery slurry hydrolyzed.
Kinetics of aflatoxin biosynthesis by Aspergillus parasiticus in the presence of Nα‐palmitoyl‐L‐lysyl‐L‐lysine‐ethyl ester dihydrochloride or dichlorvos
Authors: Yousef Ahmed E. , Marth Elmer H. 
Published: December 2004

AbstractNα‐Palmitoyl‐L‐lysyl‐L‐lysine‐ethyl ester dihydrochloride (PLL) has antimicrobial properties and may be useful as a food preservative. This study was conducted to see if PLL can inhibit growth and synthesis of aflatoxin by Aspergillus parasiticus. Growth of mold and accumulation of aflatoxins were monitored for up to 15 days. To compare these data with those of a known inhibitor of aflatoxin synthesis, dichlorvos was added to media, and mold growth and aflatoxin accumulation were monitored. The kinetic model of Brown and Vass that correlates growth and formation of secondary metabolites was applied to results of this study, and values for maturation time (tm) and aflatoxin accumulation rate constant (α) were calculated. Values of tm decreased when cultures contained PLL, whereas presence of dichlorvos resulted in a considerable increase. The lag phase of mold growth increased in the presence of PLL. The values of α increased with an increasing amount (up to 300 ppm) of PLL in media. Higher concentrations of PLL decreased the value of α. All levels of dichlorvos tested decreased the value of α. The aflatoxin accumulation rate constant (α) as a function of concentration of additive (C) followed the general equation:

where αm, Ka, and Ki are constants.
New concepts for rapid yeast settling. I. Flocculation with an inert powder
Authors: Weeks M. G. , Munro P. A. , Spedding P. L. 
Published: December 2004

AbstractA novel technique for settling microorganisms has been described. The technique involves adding a dense, inert powder to a suspension of microorganisms under conditions where flocculation of the microorganism with the inert poweder occurs. The flocs formed are small and relatively dense and settle rapidly. Suspensions of Saccharomyces cerevisiae yeast have been flocculated with several different inert seed materials achieving rapid settling and separations of up to 99.9%. Nickel powder was used as a seed material for most experiments described here, and iron sand showed promise as a cheaper seed for large‐scale use. The degree of flocculation and cell separation obtained depended largely on the seed concentration and the components in solution. Temperature and pH had little effect. When the method was initially applied to a practical fermentation, flocculation was poor because of inhibiting compounds in the fermentation medium, but modification of the technique produced good flocculation in the medium.
New concepts for rapid yeast settling. II. pH switching with an inert powder
Authors: Weeks M. G. , Munro P. A. , Spedding P. L. 
Published: December 2004

AbstractA new technique is outlined for the rapid settling of yeast cells in fermentation media. The technique involved the addition of dense, inert particles (nickel powder) to a yeast suspension (Saccharomyces cerevisiae) at pH 4.5 and a rapid change of pH to 8.0–9.0. When the pH was changed large flocs formed immediately and settled rapidly, leaving a clear supernatant. On returning the pH to 4.5 the flocs were destroyed. This technique gave larger flocs and higher settling rates than the constant pH method, and much lower nickel/yeast ratios were required. Good flocculation also occurred in a fermentation medium. The technique was used to recycle yeast cells to a semicontinuous ethanol fermentation. Application of the technique to this and similar systems is discussed. The factors affecting yeast/inert powder flocculation are also discussed and a model is proposed to explain the observed experimental behavior for flocculation with a rapid change in pH.
The use of chaotropic salts for separation of ribonucleic acids and proteins from yeast nucleoproteins
Authors: Damodaran Srinivasan , Kinsella John E. 
Published: December 2004

AbstractThe effect of chaotropic salts on the dissociation of ribonucleic acid from yeast nucleoprotein complex was studied. The effectiveness of various salts on the dissociation of ribonucleic acid followed the chaotropic series; i.e., Cl3CCOONa = NaClO4 > NaBr > NaCl. Treatment of the nucleoprotein complex with 0.5M Cl3CCOONa or NaClO4 resulted in RNA removal of about 80%, whereas NaCl and NaBr removed only about 10 and 25%, respectively. Based on the results presented, a simple and novel method for industrial‐scale preparation of single‐cell proteins with low levels of nucleic acid is proposed.
Computer control of the penicillin fermentation using the filtration probe in conjunction with a structured process model
Authors: Nestaas Eirik , Wang Daniel I. C. 
Published: December 2004

AbstractA structured model for the penicillin fermentation is presented. This model includes three different cell types: (1) hyphae tips, (2) penicillin‐producing cells, and (3) degenerated, metabolically inactive cells. Cell degeneration has been described previously as a gradual loss of cytoplasmic material by endogenous metabolism. The rate at which such loss of cytoplasm (and activity) proceeds can be expressed as a linear function of the specific growth rate. At growth rates above some minimum value (0.0115 h−1) cell degeneration can be prevented. This model served as the control basis during open‐loop as well as closed‐loop computer control of the fermentation. Closed‐loop control was achieved through feedback information of biomass concentration using a filtration probe and was required when complex nutrients contributed significantly to the overall biomass production.
Some practical aspects of computer applications in a fermentor hall
Authors: Meiners M. , Rapmundt W. 
Published: December 2004

AbstractThe use of computers in a fermentation pilot plant is described from a practical point of view. The aim is not the application of a computer to a single special process but a general application of computers to prepare and present data for the following analysis of fermentation processes. The hardware is normally bought from computer manufacturers, but some additional installations are useful. Application software has to be developed by the biotechnologist, therefore the software structure is the most important part of the computer application. Data storage is divided into three parts: short‐time memory, long‐time storage, and a medium memory mainly to be used in process analyses and process control. Four types of programs are used: main schedule tasks, low‐priority on‐line tasks, sense‐switch routine, and different off‐line programs. A table of all programs is presented, the main schedule task is described in detail to demonstrate the software structure.
Determination of substrate concentrations by a computerized enzyme electrode
Authors: Kernevez J. P. , Konate L. , Romette J. L. 
Published: December 2004

AbstractA numerical treatment of the signal produced by an electrode onto which an artificial enzyme membrane is mounted can give the concentration of the substrate (glucose, saccharose, lactose, amino acids, etc.) in solution. In the example of a glucose analyzer, in which glucose oxidase catalyzes the oxidation of glucose, the computer receives pO2 level data from the electrode and calculates the glucose concentration. The transient electrode signal, measured as the enzyme membrane is exposed to a solution of glucose, is least‐square approximated by a third‐degree polynomial whose slope at inflection point is characteristic of the external glucose concentration. A calibration procedure provides a cubic spline approximation of glucose concentration as a function of slope, thus enabling automatic measurement of samples. The computer performs the calculations, and actuates valves for air rinsing, introduction of the sample, and water rinsing.
The deposition of bacterial cells from laminar flows onto solid surfaces
Authors: Powell Martin S. , Slater Nigel K. H. 
Published: December 2004

AbstractIn a previous article, the authors proposed a simple model for the rate of removal of bacterial cells from solid surfaces by fluid shear. This Model has been extended to include the deposition of cells from a flowing suspension. The theory is compared to experimentally obtained data for the deposition of Bacillus cereus cells onto the surface of glass capillaries. The effect of a hydrophobic surface, siliconized glass, and the addition of an antifoam agent to the suspension is also investigated.
Optimization of batch fermentation processes by graphical method
Authors: Staniškis J. , Levišauskas D. 
Published: December 2004

AbstractA graphical method is proposed for batch fermentation process optimization. Its objective function is the maximum output of the product when the time of process is fixed or free. The technique of optimization is based on Bellman's dynamic programming concepts and the assumption that the process can be described by mathematical models of generalized structure. An example of the proposed technique's application is presented.
Arachidonic acid production by the red algaPorphyridium cruentum
Authors: Ahern Tim J. , Katoh Shigeo , Sada Eizo 
Published: December 2004

AbstractThe single‐celled alga,Porphyridium cruentum, was assessed by means of chromatographic separation and mass spectral analysis of its fatty acids to be a potentially competetive source of arachidonic (5,8,11,14‐eicosatetraenoic) acid. Models for both cell growth and production of the prostaglandin precursor at various temperatures and light intensities are presented. Increasing the light intensity within the range 1700–8000 lux increases the cell growth rate without affecting the arachidonic acid yield per cell; increasing the cultivation temperature from 18°C to ca. 32°C lowers the yield of arachidonic acid per cell but increases the rate of its production per unit volume and time. The increase of the weight ratio of arachidonic:palmitic acids at low temperatures is interpreted as a means of controlling the microviscosities of cellular membranes. In addition, the arachidonic acid content of cells decreases with the culture's age, despite increases in unit cell dry weight. The maximum rate of 0.46 mg arachidonic acid L−1h−1was calculated by means of the model to occur at ca. 32°C and 8000 lux in liquid cultures of 12 × 109cells/L. Estimates of the cost of producing arachidonic acid by means of this alga range from $0.15/g to $1.00/g of arachidonic acid. Cells grown at 18°C in the presence of 0.3% linoleic acid swelled and produced gorlic (13‐cyclopent‐2‐enyltridec‐6‐enoic) acid and another compound not normally observed. An estimated threefold increase of arachidonic acid content also occurred, but no significant lipogenesis was induced at 23°C in the presence of 1% kerosene or 0.3% palmitic, stearic, oleic, or linoleic acids.
The effect of carbon dioxide on the production of an extracellular nuclease of Staphylococcus aureus
Authors: Quirk A. V. , Plank R. W. H. 
Published: December 2004

AbstractThe production of the extracellular nuclease secreted by Staphylococcus aureus (Foggi strain) was studied in a fermentor in an attempt to improve yield and allow large‐scale production of the enzyme. In shake flask cultures, 600 units/mL of the enzyme were produced routinely. However, only 450 units/mL of the enzyme at best were obtained in a small‐scale fermentor (3 L). The supplementation of the air supply to the fermentor with carbon dioxide [20% (v/v)] increased levels of enzyme in the culture medium to 770 units/mL. Subsequently, this result was reproduced in larger fermentors (10 and 150 L). The possible mechanisms of the effect of carbon dioxide upon the growth of Staphylococcus aureus (Foggi) and the production of the enzyme are discussed.
Bioconversion of hemicellulose: Aspects of hemicellulase production by Trichoderma reesei QM 9414 and enzymic saccharification of hemicellulose
Authors: Dekker Robert F. H. 
Published: December 2004

AbstractThe growth of Trichoderma reesei QM9414 in shake flasks at 28°C on hemicellulose substrates and bagasse resulted in rather low yields of hemicellulolytic enzymes (1.0–1.5 units/mL xylanase and 0.05–0.08 units/mL β‐xylosidase). The influence of pH on the synthesis of β‐xylosidase was greater than on the synthesis of xylanase. Both xylanase and β‐xylosidase showed optimal activity at pH 4–5 and 55–60°C. Xylanase was stable at pH 2–10 but was heat labile and totally inactivated after 1 h at 65°C. Enzyme stability towards heat could be increased in the presence of bovine serum albumin. The β‐xylosidase was more tolerant to heat, but stable over a pH range 2.5–6.0. The D‐xylose inhibited both enzymes in a competitive manner. Hemicellulose (heteroxylan) was degraded to the extent of 30–40%within 24 h. The degree of hydrolysis decreased as the substrate concentration increased and increased with increased amounts of enzyme. Multiple enzyme doses resulted in increased saccharification in reduced times. The degree of hydrolysis was influenced by the amount of β‐xylosidase present in the hemicellulolytic enzyme preparation. The ‐;xylosidase was demonstrated to play an important role in the overall conversion of heteroxylan into xylose that is analogous to the role of β‐glucosidase in the saccharification of cellulose by cellulases.
A minicomputer system for analyzing and reporting pilot plant fermentor data
Authors: Bowski Leo , Perley Christopher R. , West John M. 
Published: December 2004

AbstractIn 1979, a minicomputer system was developed for Hoffmann‐La Roche by ABEC, Inc. for the purpose of achieving on‐line analysis and reporting of data from 16 70‐L pilot‐plant fermentors (New Brunswick Scientific Co.). The system consists of a PDP 11/60 computer with 96K core capacity, two RL01 disk drives, two RX01 floppy‐disk drives, LA‐36 DECwriter terminal, Tektronix CRT, and Versatec printer plotter. DEC, PDP, RSX, RL01, RX01, LA‐36, and DECwriter are trademarks of Digital Equipment Corporation. The computer software comprises three distinct groups of programs. RSX‐11M is a disk‐based operating system that allows quick response to realtime events, such as process monitoring and data acquisition, while carrying out less time‐dependent activities, such as program development and graphical output. The AIM (Biles, Inc.) system is used to acquire and convert the voltage signals produced by pilot‐plant instrumentation into engineering units. Analysis and graphical output are executed by ABEC and Versatec supplied programs. The most beneficial task performed by the computer is the production of graphical output of a variety of measured and analyzed data. This has led to an increase in personnel productivity and design of more meaningful experiments. An ancillary function of the system is to pick up data logged by a PDP 11/03 computer from a remote fermentation production plant by means of a MODEM interfaced communication link. Production data are analyzed and presented in a form identical with pilot‐plant data. The experience with the system is discussed in this article.
Purification of chymotrypsin by subunit exchange chromatography on the denatured protein
Authors: Carrea G. , Pasta P. , Antonini E. 
Published: December 2004

AbstractThe α‐chymotrypsin subunits immobilized under denaturing conditions (6 M urea or 1% SDS) on CNBr‐activated Sepharose 4B, were found to interact with soluble chymotrypsin subunits with the formation of oligomers higher than dimers. Subunits immobilized under nondenaturing conditions form only dimers. The effects of several parameters, such as organic solvents, cations, and anions of the lyotropic series, on the associating properties of the immobilized derivatives were examined. The interaction between immobilized and free enzyme was shown to be specific because extraneous proteins and compounds were not bound by the derivatives. Chymotrypsinogen, studied analogously, did not show appreciable self‐associating capacity. Chymotrypsin subunits immobilized under denaturing conditions and packed in a column proved to be suitable for the purification of chymotrypsin from both bovine and porcine pancreatic extracts. The “subunit exchange” chromatography of such extracts, carried out between pH 2.5 and 4, gave an eightfold purification with a 93% recovery of chymotryptic activity. The specific activity was ca. 12,000 Schwert and Takenaka units/mg. Only 6% of the tryptic activity was bound by the column. The capacity of the matrix, 6 mg chymotrypsin/mL, dropped to about 70% of the original value after
Growth of three established cell lines on glass microcarriers
Authors: Carani James , Dame Michael , Beals Ted F. , Wass John A. 
Published: December 2004

AbstractThree established cell lines were examined for growth on a newly developed microcarrier which consists of glass beads. The cells were simultaneously exmined for growth on commercially available microcarriers made from DEAE‐dextran and from plastic. Cell yields on the glass microcarriers were comparble to the cell yields on the commercially available products. Cells grown on the glass microcarriers were easily separated from the substratum by trypsinization (as were the cells grown on the plastic substratum) while the cells grown on the DEAE‐dextran particles were much more trypsin resistant. After removal of cells from the glass microcarriers, the cells reattached and spread out in plastic flasks as readily as cells harvested from monolayer. Scanning electron microscopy revealed dramatic differences in the appearence of the cell grown on the glass microcarriers and cells grown on the DEAE‐dextran microcarriers. On the glass microcarriers, cells attached to the substratum through lond, slender filopodia while on the DEAE‐dextran microcarriers, the entire edge of the cell appeared to be in contact with the substratum. This dissimilarity in attachment could underly the difference in sensitivity to trypsin‐mediated detachment. Finally, the glass microcarriers were washed after being used once and retested for their ability to support cell growth a second time. Nearly identical results were obtained with the reprocessed beads as with previously unused ones.
Inversion of sucrose by immobilized β‐fructooxidase in an integral reactor
Authors: Annesini M. Cristina , Gaudioso Domenico , Toro Luigi 
Published: December 2004

AbstractExperimental runs on the inversion of sucrose by means of immobilized β‐fructooxidase are reported. External mass‐transfer and axial dispersion phenomena have been analyzed. It has been observed that external mass‐transfer plays a significative role in the overall kinetics, while axial dispersion phenomena are negligible.
Continuous transformation of benzaldehyde to benzyl alcohol by Rhodotorula mucilaginosa immobilized in an ultrafiltration cell
Authors: Wiśniewski J. , Winnicki T. , Majewska K. 
Published: December 2004

AbstractMicrobiological transformation of benzaldehyde accomplished by the fungus Rhodotorula mucilaginosa immobilized in the ultrafiltration cell was studied. A polysulfone membrane formed on a sintered PVC support was used for the separation of the transformation product from the cellular material. Kinetic investigations have led to results which are typical of continuously fed stirred tank reactors (CFSTR)—the value of the maximum reaction rate (Vmax) and apparent Michaelis constant (K′m) are practically independent of the substrate retention time (calculated in terms of the flow intensity value). A strong relationship was found to occur between Vmax and biomass concentration in the reactor. Study of the apparent enzyme stability shows that the decrease in the biocatalyst activity is chiefly caused by penetration of the cells through the membrane. The experimental results were approximated in terms of the adopted mathematical model. Based on this model, the half‐lives (t1/2) of enzyme activities were determined. The t1/2 value varies from 35 to 82 days and depends both on the permeate flux through the membrane and on the separation properties of the membrane.
Producton of single‐cell protein from cellulose by Aspergillus terreus
Authors: Miller T. Ferrell , Srinivasan V. R. 
Published: December 2004

AbstractCellulose fermentation studies were conducted with a thermotolerant strain of Aspergillus terreus. Batch cultivation of A. terreus using purified or complex cellulose showed that 80–88% of the available cellulose was utilized in 30–36 h with an average doubling time of 7.5–8.3 h. The protein content in the biomass ranged from 23 to 38%. Semicontinuous cultivation studies, in which 90% of the biomass was withdrawn at the end of growth cycle, indicated that 84% of added cellulose was utilized with the biomass containing 32% crude protein. No loss in cellulose consumption, growth rate, or protein production occurred through two growth cycles. Continuous cultivation of A. terreus showed that 78–84% cellulose consumption occurred over growth temperatures ranging from 35 to 45°C. Maximum specific growth rates (0.14 h−1) occurred at 40 and 45°C with a minimum doubling time of 4.9 h.