bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of a two‐phase combination fermenter for the conversion of cellulose to methane
Authors: Khan A. W. , Miller S. Shea , Murray William D. 
Published: December 2004

AbstractCellulose degradation to methane under continuous fermentation conditions was compared using fully mixed, fully mixed with solids return, sludge‐blanket, and fixed‐film fermenters. In fully mixed fermenters, a decrease in hydraulic retention time (HRT) of two weeks or less caused the wash out of anaerobes capable of converting volatile fatty acids to methane, while at increased feeding rates over 1 g/L day the rapid growth of cellulolytic anaerobes upset the balance between acid formation and its conversion to CH4. Circulation of cellulose and difficulty in settling of cellulose with attached bacteria imposed problems in the use of other types of fermenters. On the basis of information obtained from this study, a fermenter which combined a fully mixed phase for cellulose degradation and a fixed‐film phase with pre‐immobilized bacteria for converting fatty acids to CH4 in one vessel, was devised. Using this fermenter, a mixed culture converted cellulose to CH4 at 4.8 g/L day at a HRT of six days as compared to 0.7 g/L day at a HRT of 28 days in the fully mixed fermenter.
Anaerobic treatment of raw domestic sewage at ambient temperatures using a granular bed UASB reactor
Authors: Lettinga G. , Roersma R. , Grin P. 
Published: December 2004

AbstractResults obtained in a 120 liter 2 m high UASB‐reactor with raw domestic sewage and using a granular sugar beet waste cultivated seed sludge, reveal the feasibility of this type of anaerobic treatment for domestic sewage. Under dry weather conditions 65‐85% COD reduction can be achieved at temperatures in the range of 8‐20°C and at hydraulic loads as high as 2 m3 · m−3 · day−1. In the case of heavy rainfall the COD‐reduction drops to 50‐70% and occasionally, viz.at very low influent COD, even below 50%. The net methane production amounts to 7.1‐7.3 m3 · PE−1 · year−1, and the excess sludge production ranges form 5.0‐8.6 kg TS · PE−1 · year−1. Regarding the results obtained anaerobic treatment of raw sewage not only looks an attractive proposition for tropic areas but also for moderate climatic areas.
Ethanol production from fodder beets
Authors: Kosaric N. , Wieczorek A. , Kliza S. 
Published: December 2004

AbstractVarious yeasts such as two strains of Saccharomyces cerevisiae, Saccharomyces diastaticus, and Kluyveromyces marxianus were investigated for their ability to ferment fodder beet juice to alcohol. Juice extracted from fodder beet roots without any additives was used as a fermentation substrate. The fermentation kinetic parameters were determined and compared for each species of yeast tested. The best species for fodder beet juice fermentation was chosen and products obtained by fermentation of one hectare of fodder beet plants are given.
Effect of pretreatment on the hydrolysis of cellulose by Penicillium funiculosum cellulase and recovery of enzyme
Authors: Rao Mala , Seeta R. , Deshpande Vasanti 
Published: December 2004

AbstractPenicillium funiculosum produces a complete cellulase which brings about 97% hydrolysis of cotton and has high β‐glucosidase, xylanase, laminarinase, and lichenase activities. This article deals with the effect of different pretreatments on the hydrolysis of sugarcane bagasse by P. funiculosum enzymes and the recovery of enzyme from the insoluble residues. Enzymic saccharification of bagasse pretreated with hot 1N NaOH followed by neutralization with HCI and steam treated under pressure (7 kg/cm2) gave 63 and 59% saccharification, respectively, in 48 h. Hemicellulose is not lost in these pretreatments. With a 30% slurry of steam‐treated bagasse, a semisolid mass containing 14% sugar was obtained. A 90% recovery of CMCase, β‐glucosidase, and filter paper activity from the hydrolysates was obtained under the following conditions: (1) maintaining the ratio of enzyme to substrate high by stepwise addition of substrate, (2) brief grinding of the residual substrate with glass powder, and (3) addition of 0.4% Tween‐80 to the eluting buffer. The high recovery of cellulolytic enzymes indicates that the adsorption of these enzymes on cellulose is not irreversible.
Effect of oxygen removal on hydrogen photoproduction in algae
Authors: Rosenkrans Addison M. , Rosen Michael M. , Krasna Alvin I. 
Published: December 2004

AbstractHydrogen photoproduction from water in Scenedesmus cells requires removal of oxygen by a reagent in contact with the algae. Both deoxyhemoglobin and deoxymyoglobin stimulated hydrogen production by reversible absorption of oxygen. Their effectiveness was greatly increased when other oxygen‐combining reagents were present in a separate chamber with deoxyhemoglobin and deoxymyoglobin serving as reversible oxygen transfer agents.
Maximum photosynthetic efficiency: A problem to be resolved
Authors: Pirt S. J. 
Published: December 2004

AbstractThe great disarray in the measurements of the maximum efficiency of conservation of light energy in photosynthesis is an outstanding problem in the development of photosynthetic biotechnology. The short‐term measurements of the efficiency based on O2 release by suspensions of cells or chloroplasts have given minimum quantum demands between 4 and 12 hv/O2. The defect of the short term measurements is that the effects of growth conditions, which can alter the efficiency by a factor of 2, have been generally ignored. In contrast, the steady‐state growth method, which depends on measurement of the maximum growth yield in photosynthesis, ensures that growth and photosynthesis are normally coupled. This growth method indicates that the minimum quantum demand lies in the relatively narrow range of 5.3 to 8.6 hv/O2. The question of whether the minimum quantum demand is less or greater than 8 hv/O2 is a crucial test for present theoretical concepts of the conversion of radiant energy to chemical energy in photosynthesis. To obtain the definitive maximum value more rigorously controlled measurements of photosynthetic efficiency in growing organisms are essential.
Continuous production of high‐glucose syrup by chitin‐immobilized amylase
Authors: Flor Perfecto Q. , Hayashida Shinsaku 
Published: December 2004

AbstractA simple method of preparing a chitin‐immobilized α‐amylase and glucoamylase from the protease‐ and glycosidase‐less Mutant HF‐15 of Aspergillus awamori var. kawachi was developed and used for the production of high‐glucose syrup. The glucoamylase was tightly bound onto chitin without the aid of a crosslinking agent because the enzyme contained a specific binding site for chitin. Continuous production of high glucose concentrate from a highly concentrated α‐amylasetreated gelatinized starch substrate (about 45% total solids) was undertaken successfully with the use of a column‐packed chitin‐immobilized amylase. The activity of the column was stable for more than 20 days of continuous operation and the product was found to be only glucose with an average dextrose equivalent value of more than 97%. The final product showed no isomaltose or panose contamination, indicating that the immobilized amylase had no transglucosidation activity. The immobilized amylase was most active in the conversion of gelatinized starch to glucose at 55°C and pH 2.5 to 5.0. Drying the chitin‐immobilized amylase resulted in the decrease of activity and shortening of storage life, whereas a storage life of up to 80 days was attained without affecting its original activity when kept under moist condition at 4°C.
Kinetic study on enzymatic hydrolysis of cellulose by cellulose from Trichoderma viride
Authors: Ohmine Kazuo , Ooshima Hiroshi , Harano Yoshio 
Published: December 2004

AbstractPure cellulose (Avicel) was hydrolyzed batchwise at 50°C and pH 4.8 by cellulase from Trichoderma viride (Meicelase CEP). Then the effects of the crystallinity of cellulose as well as the thermal deactivation and product (cellubiose and glucose) inhibition to cellulose on the hydrolysis rate were quantitatively investigated. While these factor had evidently retarded the enzymatic hydrolysis of cellulose to a significant extent, the hydrolysis rates observed could not be explained. For practical purposes, an empirical, simple rate expression was developed which included only one parameter: a overall rate retardation constant. This empirical rate expression held for the hydrolysis of at least two kind of cellulosic materials: Avicel and tissue paper.
Thienamycin production by immobilized cells of Streptomyces cattleya in a bubble column
Authors: Arcuri E. J. , Nichols J. R. , Brix T. S. , Santamarina V. G. , Buckland B. C. , Drew S. W. 
Published: December 2004

AbstractA novel 2.0‐L columnar reactor has been developed for the production of thienamycin by cells of Streptomyces cattleya attached to celite particles. Successful immobilization of cells was achieved by operating the column continuously at a high dilution rate during the growth phase. Scanning electron micrographs of the celite particles indicate the involvement of subcellular fibrils in the attachment of cells to the solid surfaces. Reactor operation was divided into two distinct phases–a growth phase and a production phase. The kinetics of attached growth and thienamycin production were found to be strongly influenced by nutrient concentrations. The influences of nutrient concentration on CO2 production and thienamycin production during both the growth phase and the production phase are discussed.
Bacterial fermentation of cellulose: Effect of physical and chemical parameters
Authors: Armstrong David W. , Martin Stanley M. 
Published: December 2004

AbstractAcetivibrio celluloyticus converts cellulose directly to ethanol, acetate, H2, and CO2. The effects of various physical and chemical parameters, and their interdependence, including pH, temperature, redox, and ethanol toxicity on this fermentation, were studied. Controlling pH at 6.8 favored a predominance of ethanol over acetate. Supplementation of the medium with additional reductant, concomitant with a lower redox potential, incresed ethanol formation. Results from ethanol‐challenged cultures indicated that cell lysis occurs with growing but not with nongrowing cells. A stable strain was adapted for growth in ethanol concentrations almost sevenfold greater than the parent organism.
Production of sugars from wood using high‐pressure hydrogen chloride
Authors: Antonoplis R. A. , Blanch H. W. , Freitas R. P. , Sciamanna A. F. , Wilke C. R. 
Published: December 2004

AbstractSaturating wood particles with HCl gas under pressure was found to be an effective pretreatment prior to subjecting wood to dilute acid hydrolysis. Pretreament is necessary to release sugars from wood because of the tight lattice structure of cellulose. The HCl gas makes the cellulose more susceptible to subsequent acid hydrolysis and the glucose yield is doubled when dilute acid hydrolysis is preceded by HCl saturation at high pressure. The saturation was most effectively performed in a fluidized bed reactor, with pure HCl gas fluidizing an equal volume of ground wood plus inert particles. The fluidized bed effectively dissipated the large amount of heat released upon HCl absorption into the wood. Batch reaction times of 1 h at 315 psia gave glucose yields of 80° and xylose yields of 95° after dilute acid hydrolysis. A model was developed which proposed gas diffusing through the solid as limiting the reaction rate and this was found to effectively describe the HCl‐wood reaction in the fluidized bed. The HCl was found to form a stable adduct with the lignin residue in the wood, in a ratio of 3.33 mole of lignin monomer. The adduct was broken upon the addition of water.
Effect of cellobiose, glucose, ethanol, and metal ions on the cellulase enzyme complex of Thermomonospora fusca
Authors: Ferchak John D. , Pye E. Kendall 
Published: December 2004

AbstractThe saccharification of cellulosic substrates by cellulase from Thermomonospora fusca, strain YX, was influenced by the presence of various substances. Cellobiose was strongly inhibitory, reducing the activity against swollen cellulose to 25% at 5% concentration. Glucose had much less effect, reducing activity to 40% at 20% concentration. Ethanol was found to be only slightly inhibitory to the cellulase, reducing activity by about 15% at 6% concentration, but much more inhibitory to the cell‐bound β‐glucosidase activity. Of the numerous metal ions examined, Ca2+ and Co2+ at 0.1mM‐1.0mM concentration were found to be slightly activating under assay conditions, while 1.0mM Pb2+ and Hg2+ were the most inhibitory ions. The implications of these results for the design of commercial processes for ethanol production from cellulose are discussed.
Enhancing gas‐liquid mass transfer rates in non‐newtonian fermentations by confining mycelial growth to microbeads in a bubble column
Authors: Gbewonyo K. , Wang D. I. C. 
Published: December 2004

AbstractThe performance of a penicillin fermentation was assessed in a laboratory‐scale bubble column fermentor, with mycelial growth confined to the pore matrix of celite beads. Final cell densities of 29 g/L and penicillin titres of 5.5 g/L were obtained in the confined cell cultures. In comparison, cultures of free mycelial cells grown in the absence of beads experienced dissolved oxygen limitations in the bubble column, giving only 17 g/L final cell concentrations with equally low penicillin titres of 2 g/L. The better performance of the confined cell cultures was attributed to enhanced gas liquid mass transfer rates, with mass transfer coefficients (kLa) two to three times higher than those determined in the free cell cultures. Furthermore, the confined cell cultures showed more efficient utilization of power input for mass transfer, providing up to 50% reduction in energy requirements for aeration.
Synergistic action of α‐amylase and glucoamylase on hydrolysis of starch
Authors: Fujii Michihiro , Kawamura Yosinori 
Published: December 2004

AbstractSynergistic action of α‐amylase and glucoamylase on hydrolysis of starch is modeled by the kinetic equations presented in this paper. At the early stage of the reaction α‐amylase acts as a contributor of newly formed nonreducing ends of starch molecules to glucoamylase by splitting the original starch molecules. This is expressed by the simultaneous differential equations which consist of each rate equation for α‐amylase and glucoamylase. After the molecular weight of the substrate decreases to the value of about 5000, which is obtained experimentally in this work, the action of α‐amylase can be neglected and the rate of formation of glucose obeys only the rate equation for glucoamylase.
Kinetics of ethanol inhibition in alcohol fermentation
Authors: Luong J. H. T. 
Published: December 2004

AbstractThe inhibitory effect of ethanol on yeast growth and fermentation has been studied for the strain Saccharomyces cerevisiae ATCC No. 4126 under anaerobic batch conditions. The results obtained reveal that there is no striking difference between the response of growth and ethanol fermentation. Two kinetic models are also proposed to describe the kinetic pattern of ethanol inhibition on the specific rates of growth and ethanol fermentation:

The maximum allowable ethanol concentration above which cells do not grow was predicted to be 112 g/L. The ethanol‐producing capability of the cells was completely inhibited at 115 g/L ethanol. The proposed models appear to accurately represent the experimental data obtained in this study and the literature data.
Ethanol fermentation of crude acid hydrolyzate of cellulose using high‐level yeast inocula
Authors: Chung I. S. , Lee Y. Y. 
Published: December 2004

AbstractHigh‐level yeast inocula was investigated as a means of overcoming the toxicity problem in ethanol fermentation of acid hydrolyzate of wood cellulose. When the inoculum level exceeded 108 initial cells/mL, 50% of the yeast cells survived the initial cell death period during which furfural and HMF were depleted. The fermentation thus proceeded to completion by virtue of cell regrowth. The specific ethanol productivity in batch fermentation on the basis of viable cells was comparable to that of pure glucose fermentation. Continuous fermentation with cell recycle was superior to batch fermentation in that there was no overall cell decline and the ethanol yield was substantially higher. The maximum ethanol productivity in continuous fermentation was 4.9 g/L h and it occurred at a dilution rate of 0.24 hr−1.
Acid hydrolysis of sweet potato for ethanol production
Authors: Kim K. , Hamdy M. K. 
Published: December 2004

AbstractStudies were conducted to establish optimal conditions for the acid hydrolysis of sweet potato for maximal ethanol yield. The starch contents of two sweet potato cultivars (Georgia Red and TG‐4), based on fresh weight, were 21.1 ± 0.6% and 27.5 ± 1.6%, respectively. The results of acid hydrolysis experiments showed the following: (1) both hydrolysis rate and hydroxymethylfurfural (HMF) concentration were a function of HCL concentration, temperature, and time; (2) the reducing sugars were rapidly formed with elevated concentrations of HCl and temperature, but also destroyed quickly; and (3) HMF concentration increased significantly with the concentration of HCl, temperature, and hydrolysis time.Maximum reducing sugar value of 84.2 DE and 0.056% HMF (based on wet weight) was achieved after heating 8% SPS for 15 min in 1N HCl at 110°C. Degraded 8% SPS (1N HCl, 97°C for 20 min or 110°C for 10 min) was utilized as substrate for ethanol fermentation and 3.8% ethanol (v/v) was produced from 1400 mL fermented wort. This is equal to 41.6 g ethanol (200 proof) from 400 g of fresh sweet potato tuber (Georgia Red) or an ethanol yield potential of 431 gal of 200‐proof ethanol/acre (from 500 bushel tubers/acre).
Chemical and enzymic pretreatment of corn stover to produce soluble fermentation substrates
Authors: Tanaka Mitsuo , Robinson Campbell W. , Moo‐Young Murray 
Published: December 2004

AbstractCorn stover was pretreated with various chemical agents, including sodium hydroxide, sulfuric acid, ethylenediamine, n‐butylamine (either alone or in solution with methanol), and acetonitrile or ethanol containing hydrochloric acid. Of these chemicals, n‐butylamine was the best reagent for pretreatment of corn stover, considering the degree of loss of total carbohydrate, delignification, cumulative weight loss, cumulative yield of reducing sugars per original total carbohydrate, and the potential ease of recovery and reuse of reagent. In comparison to the other reagents tested, n‐butylamine (n‐BA) selectively delignified corn stover. The best conditions were as follows: a 12‐h presoak of about a 155 g dry wt/L slurry (1 mm average particle size) in 100% n‐BA at room temperature, followed by 30 min of refluxing (86.5°C) with 40% (w/w) n‐BA–distilled water solution. The cumulative yield of reducing sugars after enzymic hydrolysis was 44.5% of the original total carbohydrate and the cumulative total weight loss (dry basis) was 59%. Degradative loss of total carbohydrate during pretreatment was not detected.
Gas holdup and overall volumetric oxygen transfer coefficient in airlift contactors
Authors: Bello R. Ade , Robinson Campbell W. , Moo‐Young Murray 
Published: December 2004

AbstractThe two major types of airlift contactors, concentric‐tube and external‐loop, were investigated for their gas holdup (riser and downcomer) and overall mass transfer characteristics. Results obtained in batch charges of tap water and 0.15 kmol/m3 NaCl solution are reported for external‐loop airlift contactors having downcomer‐to‐riser cross‐sectional area ratios, Ad/Ar, ranging from 0.11 ≤ Ad/Ar ≤ 0.69 and for concentric‐tube types in the range 0.13 ≤ Ad/Ar ≤ 0.56.The results are compared and contrasted for the two types of airlift contactors and also with corresponding results obtained in a bubble column (Ad/Ar = 0). Both the riser gas holdup, (εG)r, and the overall volumetric mass transfer coefficient, (KLaD)T, were found to increase with increasing gas superficial velocity and the corresponding specific gassing power input, (PG/VD)T. However, at a specified power input both (εG)r and (KLaD)T decreased with increasing Ad/Ar due to a resultant increase in circulating liquid velocity. Unifying generalized correlations for both types of airlift contactors are given for both (εG)r and (KLaD)T. These correlations are expected to be applicable as well to continuous‐liquid flow bubble columns at comparable liquid velocities.
Purification and immobilization of rabbit liver aldehyde oxidase
Authors: Angelino Steven A. G. F. , Müller Franz , van der Plast Henk C. 
Published: December 2004

AbstractAldehyde oxidase (E.C. 1.2.3.1) was isolated from rabbit liver and two potential bioaffinity ligands, i.e., 3‐aminocarbonyl‐1‐benzyl‐6‐methylpyridinium bromide and 3‐aminocarbonyl‐1‐benzyl‐4,6‐dimethylpyridinium chloride, were tested for their applicability in a purification procedure for this enzyme. Various supports and different coupling methods were investigated for the immobilization of aldehyde oxidase. Adsorption to n‐hexyl‐ and n‐octylamine‐substituted Sepharose 4B and DEAE Sepharose 6B gave the best retention of aldehyde oxidase activity. The storage stability of free enzyme and enzyme immobilized to n‐octylamine‐substituted Sepharose 4B was studied in several buffers at pH 7.8 and 9.0. This showed that the stability of immobilized enzyme was much less than that of free enzyme. The apparent operational stability of the immobilized enzyme preparation, however, improved substantially compared to soluble enzyme, although the corresponding product yield is still very poor. Coimmobilization of catalase and/or superoxide dismutase provided no significant increase of the apparent operational stability and product yield. A positive effect on both parameters was found for aldehyde oxidase‐n‐alkylamine Sepharose 4B preparations by increasing the amount of enzyme adsorbed per unit weight of support, whereas the productivity of these preparations remained about constant.
Oxygen transfer in liquids
Authors: Stejskal Jiřrí , Potůček František 
Published: December 2004

AbstractIn the laboratory‐type airlift tower reactor oxygen transfer from air in tap water and/or polyacrylamide solutions (Neuperm WF) was studied. In order to characterize the system, volumetric coefficient of oxygen transfer was determined by the gassing‐out method. Two arrangements of the airlift tower reactor were compared, namely the reactor with and without motionless mixer. In addition, mean relative gas holdup and gas power output were determined for both arrangements.
Ethanol productions from D‐xylose and cellobiose by Kluyveromyces cellobiovorus
Authors: Morikawa Y. , Takasawa S. , Masunaga I. , Takayama K. 
Published: December 2004

AbstractYeasts capable of fermenting both D‐xylose and cellobiose to ethanol were screened. Of 213 species of yeasts surveyed, Kluyveromyces cellobiovorus sp. nov., a new species belonging to genus of Kluyveromyces, was selected as the sole strain. This strain accumulated 32, 22, and 19 g/L of ethanol from 8% glucose, D‐xylose, and cellobiose, respectively. It was also shown that this strain produced ethanol from the enzymatic bagasse hydrolysate containing hexoses and pentoses more efficiently than Saccharomyces cerevisiae.
Conditions for the phase–plane analysis of feedback control of chemostat
Authors: Shimizu Kazuyuki , Matsubara Masakazu 
Published: December 2004

AbstractThis article deals with the effect of P‐control and Plcontrol on the dynamic behavior of a continuous stirred tank fermentor (CSTF). Several conditions concerning the stability of steady states and the existence of limit cycles of the closed‐loop system are derived. The application is made to the substrate inhibition model with variable yield coefficient. It is shown how the unfavorable phase–plane trajectories of the uncontrolled CSTF can be altered to favorable ones by the appropriate choice of control parameters based on the conditions derived.