bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aeration in tower‐type fermentors: Effect of tower diameter and number of aeration disks
Authors: Clark D. S. 
Published: December 2004

AbstractThe rate of oxygen absorption by aqueous sodium sulphite solutions in tower‐type fermentors up to 6 in. in diameter was related both to tower diameter and to the number of sintered Pyrex disks used for dispersing air entering the towers. Maximal rates of absorption were obtained in towers 2.5 in. in diameter. Under comparable conditions, rates of oxygen transfer in towers containing one aeration disk were approximately 30% higher than those in similar towers containing two or more disks. In towers greater than 6 in. in diameter, the absorption rate was independent of vessel diameter and number of aeration disks when more than one disk was used. Bubble coalescence was the main cause of the difference in the rate of oxygen absorption.
Methods for the production of mutants suitable as amino acid fermentation organisms
Authors: Karlström Olle 
Published: December 2004

AbstractIn order to find effective methods to isolate microorganisms that excrete large amounts of amino acids, a number of mutants of Escherichia coli ATCC 4157 were prepared and characterized. The majority were isolated for resistance to amino acid analogs. The penicillin method was also employed to select potential producer strains devoid of a biosynthetic enzyme in one case and a catabolic enzyme (tryptophanase) in another. Both of these enzymes were suspected of reducing the yield of an excerted amino acid. The identification of amino acid excreting colonies was aided by the use of pigmented auxotrophic test bacteria.Amino acid analog resistance was frequently found to increase amino acid production. In particular, excretion of valine and glutamic acid could be achieved with comparative ease. Conditions of culture were of extreme importance for the amount and kind of amino acid produced. Under certain conditions a norvaline‐resistant strain and even better a leucine‐requiring derivative of it excreted more than 2 mg./ml. of valine into the culture medium. The acetolactate‐forming enzyme of this strain was not repressible by leucine in contrast to the same enzyme in the wild type. Reversal of the growth inhibitory effects of amino acid analogs by amino acids was studied on agar plates. This method gave too complex results to be a simple guide in the selection of analogs suitable for the isolation of a particular type of production mutant.
Purification and characterization of the amylase of B. subtilis NRRL B3411
Authors: Moseley Martha H. , Keay Leonard 
Published: December 2004

AbstractThe amylase of Bacillus subtilis NRRL B3411 has been purified and partially characterized. The specific activity can be increased from 300,000 units/g to 6,000,000 units/g with a 60% recovery of total units. The purified material consists of one major and one trace anodic component as determined by disc gel electrophoresis. The molecular weight was 48,000 as determined by bio‐gel filtration; the molecular weight was 44,900 ± 2400 as determined by sedimentation equilibrium methods. This purified enzyme is stable at, 70°C in the presence of 0.01 M Ca++ and 0.1 M NaCl over a broad pH range from 5.5–9.5. The pH activity profile indicates optimum activity at pH 6.0. This amylase exhibits maximum activity at 60°C. The enzyme is a liquefying α‐amylase as determined by analysis of hydrolysis products and immunological studies.
Comparative kinetic studies on the neutral protease and thermolysin catalyzed hydrolysis of simple dipeptide substrates
Authors: Feder Joseph , Schuck James M. 
Published: December 2004

AbstractA comparative study of the Bacillus subtilis neutral protease and Bacillus thermoproteolyticus thermolysin calalyzed hydrolysis of a few dipeptide sustrates including furylacryloylglycyl‐L‐leucine amide is reported. While differences in the kcat/Km were observed between the two enzymes toward substrates in which phenylalanine or leucine donated the amino group of the peptide bond, secondary effects of substituents on the carbonyl donating amino acid and pH profiles were quite similar. Differences were also observed toward protein substrates as compared to dipeptides.
Dialysis fermentation. I. Enhanced production of salicylic acid from naphthalene Pseudomonas fluorescens
Authors: Abbott Bernard J. , Gerhardt Philipp 
Published: December 2004

AbstractThe conversion of naphthalene to salicylic acid by Pseudomonas fluorescens was studied as a model for dialysis fermentation. In a demonstration experiment, the continual removal of the product by dialysis and by intermittent replenishment of the dialysate reservoir caused cyclical changes in the concentrations of viable cells and product. The cumulative total amount of both cell mass and salicylate, however, continued to increase steadily until the experiment was terminated after 15 days. At this time the rate of product formation was highest and still increasing, although less than 10% of the cells were viable. The terminal amount of salicylate was about 20‐fold greater than the maximum reached in the control fermentation, and was calculated to be 2.6‐fold more productive even if the control were optimally recycled. Methods were projected to achieve still further improvements.
Degradation and mineralization of petroleum in sea water: Limitation by nitrogen and phosphorous
Authors: Atlas Ronald M. , Bartha Richard 
Published: December 2004

AbstractBiodegradation and mineralization of petroleum, added at 1% (v/v) to freshly collected sea water, were measured using gas–liquid chromatographic, residual weight, and CO2‐evolution techniques. Only 3% of the added petroleum was biodegraded and 1% was mineralized in unamended sea water after 18 days of incubation. Added individually, nitrate (10−2 M) or phosphate (3.5 × 10−4 M) supplements caused little improvement, but when added in combination, they increased petroleum biodegradation and mineralization to 70% and 42%, respectively. Attempts to clean up oil spills with the aid of microorganisms should take into consideration the nutritional deficiencies of sea water.
Flocculant production from kerosene
Authors: Knettig E. , Zajic J. E. 
Published: December 2004

AbstractCultivation of Corynebacterium hydrocarboclastus, which is capable of synthesizing an extracellular polymer and utilized hydrocarbons, has been reported. Growth studies in shake flasks and fermenters were made to obtain maximum polymer production. Polymer formation was found to be growth associated. The highest level of polymer accumulation was attained after 50–60 hr cultivation in the fermenter and it amounted to approximately 5.5–6 g/liter of fermentation broth. The medium contained initially 2% (v/v) kerosene as a carbon source. The maximum yield obtained corresponds to 37–40% (w/w) of kerosene supplied. At the same time the cell concentration was 10–13 g/liter which represents the yield of 67–87% (w/w). The rate of polymer production in the exponential phase was 0.25 g/liter hr and cell production rate was 0.27 g/liter hr. Sodium nitrate, 0.5%, and yeast extract, 0.3%, (w/w) were the best nigrogen sources for polymer formation. The highest level of polymer produced in broth was 6 g/liter.
Thermal inactivation of immobilized enzymes in ideal continuous reactors
Authors: O'Neill S. P. 
Published: December 2004

AbstractThe limitation of thermal inactivation on catalytic activity in continuous enzymatic reactions is considered. Where an enzyme is retained in a reaction environment which is open to mass transfer of reaction components, the effect of enzyme inactivation on reactant conversion depends on the order of the chemical reaction and the pattern of fluid flow through the reaction volume. Equations expressing conversion as a function of time for first‐order inactivation are presented for Michaelis‐Menten kinetics and the limiting fluid flow conditions of plug flow and complete back‐mixing. Substrate protection or destruction of an enzyme is also considered and it is shown theoretically that the catalytic life of an enzyme may be optimized by the proper choice of fluid flow pattern.
Covalent coupling of pullulanase to an acrylic copolymer using a water soluble carbodi‐imide
Authors: Mårtensson Kaj , Mosbach Klaus 
Published: December 2004

AbstractPullulanase (EC 3.2.1.9) prepared from a culture of Acrobacter aerogeneshas been covalently bound to an inert crosslinked copolymer of aerylamide‐acrylic acid by using a water‐soluble carbodi‐imide. The binding yield based on the amount of added pullulanase was 34%. The residual enzymic activity was 43%, of that of free enzyme. Coupling in the presence of the substrate pullulan gave a 5‐fold increase in activity over that obtained when substrate was lacking. The effect of different carbodi‐imide concentrations on the coupling has been investigated. The isoelectric point of the pullulanase preparation (3.5–4.0) was determined using isoelectric, focusing, in order to find optimal pH conditions for the coupling procedure. The immobilized pullulanase in a packed bed column was used to debranch amylopeetin to low molecular weight amylose.
The fermentation of L‐sorbose by Gluconobacter melanogenus. II. Inducible formation of enzyme catalyzing conversion of L‐sorbose to 2‐keto‐L‐gulonic acid
Authors: Tsukada Y. , Perlman D. 
Published: December 2004

AbstractCell‐free extracts of Gluconobacter melanogenus cells grown in L‐sorbose‐containing media contained an enzyme system capable of converting L‐sorbose to 2‐keto‐L‐gulonic acid while cells grown in glycerol media did not. This inducible enzyme was located in the participate fraction of the cells.
Quantitative studies of the development of S. cerevisiae mitochondria
Authors: Ferdouse M. , Rickard Pamela A. D. , Moss F. J. , Blanch H. W. 
Published: December 2004

AbstractThe quantitative changes in mitochondria and cytochromes during transition of Saccharomyces cerevisiae from one steady state to another, while growing in continuous culture under controlled environmental conditions, were followed.No Mitochondria, or mitochondria like structures, were detectable in electron micrographs of permanganate‐fixed anaerobic cells. Microaerobiosis (3μM dissolved oxygen) was sufficient to visualize mitochondrial profiles and induce cytochromes and their sections had a reduced number of mitochondrial profiles compared with cells grown in limiting glucose.In the presence of ergosterol and Tween 80 mitochondriogenesis, whether induced by aerobiosis or glucose limitation, involved enhanced definition of crystal and outer mitochondrial membranes and increased number of profiles. Where membrane formation was limited, by the absence of aerobiosis involved eytochrome induction and profile visualization, but limited profile Proliferation; the adapted cells consequently contained fewer, but more eytochrome‐enriched, mitochondria than cells adapted in the presence of ergosterol and Tween 80.Increase in dissolved oxygen from 3μM to 52μM further enhanced membrane definition and increased the size, but not the number, of mitochondrial profiles.Evidence, obtained by measurement of eytochrome concentration per unit mitochondrial volume and per unit crystal area, support the concept that mitochondriogensis and cytochrome synthesis are not synchronized process and that cytochromes are added to or depleted from the mitochondrial cristae in response to culture conditions.
Binding of end product in the fermentation of nucleotides
Authors: Schwartz J. , Margalith P. 
Published: December 2004

AbstractFlavor enhancing nucleotides may be produced by streptomycetes. Mutants of streptomyces 772 were found to produce, under ordinary fermentation conditions, considerable amounts of 5′‐IMP and 5′‐XMP, but only traces of 5′‐GMP. This was probably due to the feedback inhibition of the end product GMP. It was shown that through suitable fermentation techniques it was possible to overcome this internal control mechanism, leading to increased yields of 5′‐GMP.
Observations of continuous culture responses to additions of inhibitors
Authors: Borzani Walter , Vairo Marina L. R. 
Published: December 2004

AbstractThe effect of potassium sorbate addition to a continuous culture of Saccharomyces cerevisiae was observed. The influence on the yeast performance depended on the way the inhibitor was added. The unsteady state continuous method seems to be the best one to obtain microorganisms' adaptation to inhibitors, and for the experimental study of microbial inhibition.
The clarification of mechanically disrupted yeast suspensions by rotary vacuum precoat riltration
Authors: Gray P. P. , Dunnill P. , Lilly M. D. 
Published: December 2004

AbstractRotary vacuum precoat filtration of bakers' yeast disrupted in a high‐pressure homogenizer is reported. Different precoat materials, knife cutting rates, and body feeds were tested on disrupted yeast suspensions ranging from 10 to 40% wt packed yeast/vol. The flow rates, solids contents, and protein and enzyme concentrations before and after filtration were determined. Filtration rates were found to be independent of precoat thickness during debris filtration. For 20% disrupted yeast, flow rates of up to 17 cm3/cm2/hr were attained at a precoat and body feed usage of 35 kg/1000 liters. By reducing the knife cutting speed to 0.025 mm/min and the body feed to 1% the filter aid usage could be reduced to 13.5 kg/1000 liters while maintaining a flow rate of 9.3 cm3/cm2/hr. In all experiments protein recoveries were in the range of 80−90% and with the four enzymes examined, recoveries ranged from 67−92%. With all the precoats tested, the product had a lower solids content than that obtained from centrifuges capable of processing similar quantities of cell debris.
Response of completely mixed systems to pH shock
Authors: George T. K. , Gaudy A. F. 
Published: December 2004

AbstractThe response of aerobically growing heterogeneous microbial populations of sewage origin to step increases and decreases in pH were studied in both once‐through and cell recycle systems. The pH range studied was 2.7 to 8.0. All studies were conducted at a dilution rate of 0.125 hr−1, and all shocks were administered from a base or preshock pH level of 6.4 to 6.7. In each experiment, the preshock or initial “steady state” was assessed, the pH of the feed changed, and the resulting transient behavior of the system examined until attainment of the new or final “steady state” was approached. The major objectives of the work were to characterize the nature of the response with respect to biomass and effluent substrate concentrations, types of microbial populations present and chemical composition of the biomass, and to obtain guidelines as to allowable change in pH in waste streams. It was found in once‐through systems that substrate removal efficiency recovered from pH levels as low as 3.0 after rather long periods of transient leakage of substrate. Cell recycle attenuated the severity of substrate leakage. In all cases of severe acid shock, the microbial population changed from predominantly bacterial‐protozoan to one consisting predominantly of filamentous fungi. Changes in chemical composition of the sludge (protein and carbohydrate content) were consistent with the population changes. Based upon the results, it can be conservatively estimated that changes in pH of no more than one unit from the neutral preshock range can be tolerated without possible disruption of biochemical efficiency of substrate removal.
Studies on adsorption of amyloglucosidase on ion‐exchange resins
Authors: Solomon B. , Levin Y. 
Published: December 2004

AbstractHighly charged water‐soluble conjugates of amyloglucosidase with a copolymer of ethylene‐maleic acid or styrene‐maleic acid were prepared and adsorbed on DEAE‐cellulose and other cationic resins. Negatively charged enzyme conjugates were also obtained by means of succinylation. The polyanionic conjugates of amyloglucosidase adsorbed on the cationic carriers show higher temperature stability than the native enzyme adsorbed on the same carriers under the same experimental conditions. The insoluble enzyme conjugate‐carrier complexes could be reused and retained their full activity while working continuously for three weeks. The application of the insoluble enzyme preparations with the above characteristics which could possibly satisfy the requirements for industry are discussed.
Immobilized enzymes: Pectin esterase covalently coupled to dorous glass particles
Authors: Weibel M. K. , Barrios Roberto , Delotto R. , Humphrey A. E. 
Published: December 2004

AbstractPectin esterase (E.C. 3.1.1.11) was covalently immobilized to porous glass particles by reaction of the native protein with pendant, benzoyl azide groups of the carrier. Enzyme loading on the carrier was 0.5 unit per ml as measured by pH stat, assay. Decreasing the size of the immobilized enzyme particles by grinding produced a 12‐fold increase in activity suggesting severe internal mass transport restrictions on turnover kinetics, Gross fractionation of the citrus pectin substrate into high and low molecular weight categories and their subsequent use in kinetic characterization shows no effect of molecular weight upon the kinetic behavior of the native enzyme. In contrast the immobilized enzyme displayed a 5‐fold increase in the apparent. Km for the high molecular weight fraction relative to that of the low molecular weight fraction. A striking difference exists in the low pH profile of immobilized pectin esterase relative to the native enzyme. Carrier matrix interactions with the polyelectrolyte substrate are invoked to explain this difference. The thermal stability of the immobilized enzyme is relatively low and displays a half‐life of approximately 2 weeks at 25°C.
Models for the continuous culture of microorganisms under both oxygen and carbon limiting conditions
Authors: Sinclair C. G. , Ryder D. N. 
Published: December 2004

AbstractTwo models for predicting the behavior of cultures of microorganisms under both oxygen and carbon limiting conditions have been evlauated on a chemostat growing Candida utilis on a glycolysis suppressing glycerol medium. The work indicated that parameter values obtained under wholly oxygen limiting or wholly carbon limiting conditions successfully predict the behavior of the chemostat under the wide range of flow and substrate concentration conditions tested. Both models are satisfactory and hence it is deduced that the simpler one may be used with confidence. It was found that Monod kinetics were applicable to the growth rate dependence on oxygen concentration but that Contois kinetics were superior for the corresponding dependence on carbon substrate concentration.
A kinetic model for microbial growth on liquid hydrocarbons
Authors: Chakravarty M. , Singh H. D. , Baruah J. N. 
Published: December 2004

AbstractA kinetic model is presented to explain microbial growth using liquid n‐alkanes as substrate. The model is based on the assumption that growth occurs on the soluble alkane and that the metabolite produced by the growing cells helps the dissolution of liquid alkanes in the aqueous medium. Growth curves based on that model fit well with growth data for batch and continuous culture reported by various authors. The model also explains the differences between the relative length of exponential and linear phases of growth reported earlier.
Enzymatic preparation of 20β‐hydroxysteroids in a two‐phase system
Authors: Cremonesi Pietro , Carrea Giacomo , Ferrara Luigi , Antonini Eraldo 
Published: December 2004

AbstractThe behavior of 20β–hydroxysteroid dehydrogenase in a two–phase system consisting of an emulsion of water with an immiscible organic solvent was investigated. The effect of several organic solvents on the stability, activity, and kinetic profile of the enzyme was considered. The most suitable system for carrying out the enzymatic reactionproved to be water–butyl acetate.The production of high quantities of 20β–hydroxysteroids in 100% yield using catalytic amount of cofactor was achieved by coupling the 20β–, hydroxysteroid dehydrogenase and the alcohol dehydrogenase–catalyzed reactions.
Microbial film fermenters: Their present and future applications
Authors: Atkinson B. , Knights A. J. 
Published: December 2004

AbstractThe productivity of growth associated fermentations is dependent upon the quantity of biomass contained in the fermenter (microbial hold‐up). In contrast, the performance characteristics of a fermenter are dominated by the form in which the microbial hold‐up occurs, i.e., whether as films, flocs, or a combination of both. Industrial fermentations using biological films include biological waste‐water treatment (trickling filter, rotating disc), the “quick” vinegar process, animal tissue culture, and bacterial leaching.Atkinson and Davies (Trans. Inst. Chem. Eng., 50, 208 (1972)), proposed a completely mixed microbial film fermenter (CMMFF) based upon the fluidized bed principle, for application to continuous operation when using growth associated systems. The potential performance characteristics of this fermenter are reviewed and the construction of a laboratory scale unit capable ofaseptic operation is described (volume 9 liters, maximum throughput 15 liter/hr). The fermenter has been continuously used for periods up to 2500 hr without contamination when growing brewer's yeast (NCYC 1026 flocculating). The experimental performance characteristics have been interpreted with the aid of the theory for the CMMFF.The knowledge and experience gained to date is used as a basis for speculation as to the future role of microbial film fermenters in the biochemical process industries.
Dynamics of liquid flow in an up‐flow reactor‐used for anaerobic treatment of wastewater
Authors: Heertjes P. M. , Van Der Meer R. R. 
Published: December 2004

AbstractBy means of stimulus‐response experiments with a Li+ tracer, a description of the fluid flow in a 30 m3 reactor, used for anaerobic treatment of wastewater, was derived. It appeared that of the three parts that could be distinguished in the reactor (the sludge bed. The sludge blanket, and the settler), the sludge bed could be described as a combination of two perfectly mixed regions with bypassing and return flows; the sludge blanket was perfectly mixed, while the fluid flow in the settler could be described as plug flow. From experiments performed under different conditions it was concluded that 60 m3 gas/day were sufficient to provide good mixing and also that the height of the sludge bed should be 2–3 m. From this last conclusion it follows, e.g., that scale‐up of the 30 m3 reactor should be done by increasing the cross section of the reactor while homogeneously distributing the influent over the bottom.
Production of microbial protein from tree bark by Phanerochaete chrysosporium
Authors: Daugulis A. J. , Bone Derek H. 
Published: December 2004

AbstractPhanerochaete chrysosporium was grown in fermentors on NaOH‐extracted maple, pine, and cedar barks at the optimum substrate concentration of 1% (w/v). The yields (mg protein/liter) on maple, pine, and cedar were 1500, 1200, and 880, respectively, which are probably due to the different lignin contents of the barks. Lignin is not utilized. The productivities at 30°C obtained for pine (4.07 × 10−2 g protein/liter hr) and cedar (2.63 × 10−2 g protein/liter hr) barks were greater than for maple (2.63 × 10−2 g protein/liter hr). The substrate (bark) was the limiting component of the fermentation. Over the 26–38°C temperature range protein productivity increased by a factor of three (1.55 × 10−2 vs. 4.61 × 10−2 g protein/liter hr) for maple bark. Low agitation rates resulted in an overproduction of cellulase and reduced levels of microbial protein.