Showing papers in "Applied Biochemistry and Biotechnology in 1994"
665 citations
TL;DR: Biochemical and molecular biology studies carried out to explore the mechanisms involved in biological control revealed that Trichoderma is a rather specific mycoparasite, whereas chitinase is involved in the degradation of the host cell wall.
Abstract: Biological control of soil-borne plant pathogens is a potential alternative to the use of chemical pesticides, which have already been proved to be harmful to the environment Several strains of the fungusTrichoderma have been isolated and found to be effective biocontrol agents of various soil-borne plant pathogenic fungi under greenhouse and field conditions Different application approaches have been used including integration ofTrichoderma with reduced doses of chemical agents Biochemical and molecular biology studies carried out to explore the mechanisms involved in biological control revealed thatTrichoderma is a rather specific mycoparasite Lectins were found to be involved in the recognition betweenTrichoderma and its host fungi, whereas chitinase is involved in the degradation of the host cell wall Genetic engineering techniques were employed in order to increase the effectiveness, stability, and biocontrol capacity ofTrichoderma spp as well as other biocontrol agents, such asPseudomonass spp andRhizobium
346 citations
TL;DR: In this article, the energy requirements and size distribution for milling wood were measured for various pilot-scale size reduction equipment, such as disk milling and Hammer milling, in order to reduce the energy consumption.
Abstract: Ethanol is being considered as an attractive alternative transportation fuel for the future. One method of producing ethanol from lignocellulose involves reducing the size of biomass to smaller particles, and using acid or enzyme treatments to hydrolyze the biomass to sugars. The size-reduction step is necessary to eliminate mass- and heat-transfer limitations during the hydrolysis reactions. However, milling to small size consumes large amounts of energy, and reducing the energy usage is critical to the overall process economics. In this study, the energy requirements and size distribution for milling wood were measured for various pilot-scale size-reduction equipment. Hammer milling used less energy than disk milling, but produced particles with a larger-size distribution. Additionally, energy requirements were measured for shredding paper and switchgrass.
158 citations
TL;DR: In this paper, the authors compared the performance of C. ljungdahlii grown on carbon monoxide, or hydrogen with carbon dioxide, and showed that the rate and yield parameters are similar for both types of plants.
Abstract: Synthesis gas provides a simple substrate for the production of fuels and chemicals. Synthesis gas can be produced via established technologies from a variety of feedstocks including coal, wood, and agricultural and municipal wastes. The gasification is thermally efficient and results in complete conversion of the feedstock to fermentable substrate.Clostridium ljungdahlii grows on the synthesis gas components, carbon monoxide, hydrogen, and carbon dioxide. Production of acetic acid and ethanol accompanies growth with synthesis gas as sole source of energy and carbon. Rate and yield parameters are compared forC. ljungdahlii grown on carbon monoxide, or hydrogen with carbon dioxide.
150 citations
TL;DR: A new phage-display vector encoding a polyhistidine tag that has been used for rapid purification of soluble antibody fragments and can provide a large diverse repertoire of candidate catalytic antibodies based on TSA selection and screening.
Abstract: Functional antibody fragments may be displayed on the surface of filamentous bacteriophage by introducing variable region genes into the viral genome at a gene encoding a viral coat protein. “Phage display” enables the isolation of antibody genes from large libraries according to the binding specificities they encode. We have constructed a new phage-display vector encoding a polyhistidine tag that has been used for rapid purification of soluble antibody fragments. An antibody library derived from immunized mice was cloned into this vector. This library was panned against the transition state analog RT3, and a high proportion of binders isolated after two rounds of panning. PCR analysis revealed that there were 24 different pattern groups. Sequencing of 15 clones within the major pattern group revealed 10 related clones with a range of point mutations. Thus, phage display can provide a large diverse repertoire of candidate catalytic antibodies based on TSA selection and screening.
121 citations
TL;DR: Investigation of enzymatic hydrolysis of polysaccharides in orange peel by commercial cellulase and pectinase enzymes to higher, more practical concentrations of orange peel solids revealed the presence of inhibitory compounds which could be removed by the filtration of hydrolyzed peel.
Abstract: We extended our previous investigations of enzymatic hydrolysis of polysaccharides in orange peel by commercial cellulase and pectinase enzymes to higher, more practical concentrations of orange peel solids. High yields of saccharification could be maintained even at substrate concentrations as high as 22–23%, but the rates of solubilization and saccharification decreased 2-3-fold. We also tested the fermentability of these hydrolysates by the yeastSaccharomyces cerevisiae, which revealed the presence of inhibitory compounds. These compounds could be removed by the filtration of hydrolyzed peel. Successful fermentations of filtered hydrolysates were achieved after pH adjustment with calcium carbonate.
114 citations
TL;DR: Apart from accumulation, many invertebrates exposed to elevated metal concentrations respond to this stress by metal-induced synthesis of metallothioneins, which makes met allothionein a potential biomarker for metal stress in invertebrate animals.
Abstract: Some species of invertebrate animals are known to be efficient accumulators of trace elements. Generally, metal accumulation by such organisms is based on efficient detoxification mechanisms, such as intracellular compartmentalization, or metal inactivation by binding to metallothioneins. Metal accumulators have often been used as accumulation indicators of environmental metal pollution. This means that, ideally, metal concentrations in the animal's body reflect quantitatively or semiquantitatively environmental pollution levels. In reality, however, many factors, such as the animal's weight and age, can disturb such quantitative relationships. These factors have, therefore, to be considered carefully before an invertebrate is utilized as accumulation indicator for metal pollution. Apart from accumulation, many invertebrates exposed to elevated metal concentrations respond to this stress by metal-induced synthesis of metallothioneins. Additionally, metallothionein in metal-loaded organisms can be present in different isoforms that are specifically synthesized in response to different metals. These facts make metallothionein a potential biomarker for metal stress in invertebrates. One possibility may be to assess parameters of metallothionein synthesis at the molecular or biochemical level. Moreover, metallothionein isoform patterns could provide information on different isoforms synthesized in response to different metals or chemicals. In any case, however, care must be taken to consider intrinsic physiological parameters, such as nutritional or developmental factors, which could also interfere with metallothionein synthesis.
101 citations
TL;DR: The DNA-hydrolyzing activity of DNA-binding autoantibodies purified from SLE patients was described and the specificity of DNA cleavage was investigated, and the rate parameters of hydrolysis by antibodies and conventional nucleases were compared.
Abstract: Catalysis by antibodies could be a frequent phenomenon if the immune system generates a sufficiently diverse number of antibodyactive sites, some of which may possess catalytic activity. A catalytic antibody can be expected to do more damage than one that simply binds antigen. The best biochemical marker of systemic lupus erythematosus (SLE) is presence of autoantibodies to DNA. In the present article, we describe the DNA-hydrolyzing activity of DNA-binding autoantibodies purified from SLE patients. The substrates employed were supercoiled plasmid, radiolabeled plasmid fragments, and oligonucleotides. Hydrolysis of DNA by the antibodies was indicated by the appearance of fragments visualized by ethidium bromide staining of agarose gels or autoradiography of polyacrylamide gels. Changes in linear dichroism values were also indicative of DNA hydrolysis. The antibody activity was purified by protein A-sepharose chromatography, high-performance liquid chromatography gel filtration, and DNA-affinity chromatography. Scrupulous control studies were done to demonstrate that DNA-hydrolyzing activity really belongs to the antibodies. Purified Fab fragments showed hydrolyzing activity, whereas the Fc fragment was inactive. The specificity of DNA cleavage was investigated, and the rate parameters of hydrolysis by antibodies and conventional nucleases were compared.
93 citations
TL;DR: The garlic plant (Allium sativum) alliinase (EC 4.4), which catalyzes the synthesis of allicin, was purified to homogeneity from bulbs using various steps, including hydrophobic chromatography, and strikingly, the roots exhibited an abundant alliInase activity, suggesting that this tissue expressed a distinct alli inase isozyme with very low homology to the bulb enzyme.
Abstract: The garlic plant (Allium sativum) alliinase (EC 4.4.1.4), which catalyzes the synthesis of allicin, was purified to homogeneity from bulbs using various steps, including hydrophobic chromatography. Molecular and biochemical studies showed that the enzyme is a dimer of two subunits of MW 51.5 kDa each. Its Km using synthetic S-allylcysteine sulfoxide (+ isomer) as substrate was 1.1 mM, its pH optimum 6.5, and its isoelectric point 6.35. The enzyme is a glycoprotein containing 6% carbohydrate. N-terminal sequences of the intact polypeptide chain as well as of a number of peptides obtained after cyanogen bromide cleavage were obtained. Cloning of the cDNAs encoding alliinase was performed by a two-step strategy. In the first, a cDNA fragment (pAli-1-450 bp) was obtained by PCR using a mixed oligonucleotide primer synthesized according to a 6-amino acid segment near the N-terminal of the intact polypeptide. The second step involved screening of garlic lambda gt11 and lambda ZAPII cDNA libraries with pAli-1, which yielded two clones; one was nearly full length and the second was full length. These clones exhibited some degree of DNA sequence divergence, especially in their 3' noncoding regions, suggesting that they were encoded by separate genes. The nearly full length cDNA was fused in frame to a DNA encoding a signal peptide from alpha wheat gliadin, and expressed in Xenopus oocytes. This yielded a 50 kDa protein that interacted with the antibodies against natural bulb alliinase. Northern and Western blot analyses showed that the bulb alliinase was highly expressed in bulbs, whereas a lower expression level was found in leaves, and no expression was detected in roots. Strikingly, the roots exhibited an abundant alliinase activity, suggesting that this tissue expressed a distinct alliinase isozyme with very low homology to the bulb enzyme.
92 citations
TL;DR: In this paper, an analysis of energy flows is presented for ethanol production as an example of these technologies, and a carbon dioxide balance is provided for the fossil fuels used, including consideration of fuel utilization performance and assignment of carbon dioxide to coproducts.
Abstract: A number of transportation fuels can be produced from renewable resources. The major fractions of lignocellulosic biomass, cellulose and hemicellulose, can be broken down into sugars that can be fermented into ethanol. Biomass can also be gasified to a mixture of carbon monoxide and hydrogen for catalytic conversion into methanol. Algae could consume carbon dioxide from power plants and other sources to produce lipid oil that can be converted into a diesel fuel substitute. Through anaerobic digestion, a consortium of bacteria can break down lignocellulosic biomass to generate a medium-energy-content gas that can be cleaned up for pipeline-quality methane. Catalytic processing of pyrolytic oils from biomass produces a mixture of olefins that can be reacted with alcohols to form ethers, such as methyl tertiary butyl ether (MTBE), for use in reformulated gasoline to reduce emissions. Each of these technologies is briefly described. The costs have been reduced significantly for biofuels, and the potential exists for them to be competitive with conventional fuels. An analysis of energy flows is presented for ethanol production as an example of these technologies, and a carbon dioxide balance is provided for the fossil fuels used. This analysis includes consideration of fuel utilization performance and assignment of carbon dioxide to coproducts. Biofuels technologies are shown to require little, if any, fossil fuel inputs. As a result, most or all of the carbon is recycled through their use, reducing substantially the net release of carbon dioxide to the atmosphere.
90 citations
TL;DR: It was shown that both SGT and IGT preparations catalyze acceptor reactions and transfer the glucose unit from sucrose onto maltose to produce glucooligosaccharides, which were synthesized in the Ln series and in the Bn series, which resisted the action of these enzymes.
Abstract: Glucosyltransferase activities, produced by batch culture ofLeuconostoc mesenteroides NRRL B-1299, were recovered both in the culture supernatant (SGT) and associated with the insoluble part of the culture (IGT). A total glucosyltransferase activity of 3.5 U/mL was measured in batch culture. The enzymes from the supernatant were purified 313 times using aqueous two-phase partition between dextran and PEG phases, yielding a preparation with 18.8 U/mg protein. It was shown that both SGT and IGT preparations catalyze acceptor reactions and transfer the glucose unit from sucrose onto maltose to produce glucooligosaccharides. Some of the glucooligosaccharides synthesized (Ln series) contain α-(l→6) osidic linkages and a maltose residue at the reducing end. They were completely hydrolyzed by glucoamy-lase and dextranase. The other glucooligosaccharides synthesized (Bn series) resisted the action of these enzymes. The tetrasaccharide of this series has been characterized by13C NMR. Its structure was determined as 2–O–α–D–glucosylpanose. The oligosaccharides synthesized by the maltose acceptor reaction with the SGT and IGT preparations only differed in the relative amounts in which they were produced. The difference may arise from diffusional limitations appearing when the insoluble catalyst is used. Under the assay conditions, the glucanase resistant oligosaccharide yield was 35% with both glucosyltrans-ferase preparations.
TL;DR: Experimentation indicated that sodium ions, which were present in high concentrations in the effluent, were interfering with the ability of the cells to bind nickel, so biosorption data from experiments with live cells were more consistent.
Abstract: A study was undertaken to determined if a suitable biosorbent could be found for removal of nickel at low concentrations (< 20 parts per million [ppm]) from a chemically complex wastewater effluent generated by electroplating operations. Algae and cyanobacteria were chosen as candidate biosorbent materials because they are easy to grow and they have the ability to withstand processing into biosorbent materials. Several species were screened for nickel-biosorption capacity initially, and three species of cyanobacteria were selected for further study based on their performance in the scoping tests. When compared to live controls, autoclaving improved the binding capacities of all three species, but usually biosorption data from experiments with live cells were more consistent. None of the three species was able to bind nickel efficiently in actual effluent samples. Further experimentation indicated that sodium ions, which were present in high concentrations in the effluent, were interfering with the ability of the cells to bind nickel. Adsorption isotherm plots for biosorption of nickel by two species of Anabaena in NiCl2-deionized water solutions were prepared.
TL;DR: The inability to fermentl-arabinose appears to be a consequence of inefficient or incomplete assimilation pathways for this pentose sugar.
Abstract: Various wild-type yeasts and fungi were screened to evaluate their ability to fermentl-arabinose under oxygen-limited conditions when grown in defined minimal media containing mixtures ofl-ara-binose,d-xylose, andd-glucose. Although all of the yeasts and some of the fungi consumed arabinose, arabinose was not fermented to ethanol by any of the strains tested. Arabitol was the only major product other than cell mass formed froml-arabinose; yeasts converted arabinose to arabitol at high yield. The inability to fermentl-arabinose appears to be a consequence of inefficient or incomplete assimilation pathways for this pentose sugar.
TL;DR: Experimental data indicated that urease in a buffer-free solution was less susceptible to the inhibition of substrate product, and suggested that the noncompetitive pattern of the product inhibition, which is not significantly affected by temperature, increases gently with increasing pH.
Abstract: The kinetics of urea hydrolysis catalyzed by urease, mainly in the absence of buffers by use of the self-buffer effect of the products, was investigated. The effect of pH, temperature, and concentration of enzyme, substrate, product, salt ions, and buffers on the kinetic behavior of urease was examined. A kinetic model of a modified Michaelis-Menten form, incorporating substrate and product inhibition, pH dependence, and temperature effect, was developed to describe the reaction rate. Experimental data indicated that urease in a buffer-free solution was less susceptible to the inhibition of substrate product. The Michaelis constant keeps almost constant with the variation of pH and temperature, and increases with the addition of buffers and salts. The data also suggested that the noncompetitive pattern of the product inhibition, which is not significantly affected by temperature, increases gently with increasing pH. A Monod form rate expression was proposed to analyze the pH effect on the maximum rate. The proposed kinetic model was also examined by the long-time experiments in which pH, substrate, and product concentration varied obviously during the reaction course.
TL;DR: In this article, the effects of dilute sulfuric acid and steam explosion pretreatments on the fractionation and kinetics of the dilute acid hydrolysis of the cellulosic fraction in different biomass substrates were analyzed.
Abstract: This article analyzes the effects of dilute sulfuric acid and steam explosion pretreatments on the fractionation and kinetics of the dilute acid hydrolysis of the cellulosic fraction in different biomass substrates. A total of nine biomasses were analyzed: three hardwoods, two soft-woods, and four types of herbaceous material. Sigmacell, a purified microcrystalline cellulosic substrate, was also studied as a reference.
TL;DR: The approach described in this article could be used by potential industrial producers to complement their forecasting of the technical and economic feasibility of producing chemicals and materials from renewable resources, and by researchers to identify opportunities for focused research and development.
Abstract: A wide range of chemicals and materials can be produced from renewable feedstocks through bioconversions. An iterative, progressively detailed technology screening approach was developed to identify the most promising candidates. Initially, candidates are selected into a portfolio based on their future potential as large-volume industrial chemicals or materials. Second, the candidates are ranked with respect to a simple economic criterion based on the market value, the price of the starting material, and the product yield. Simple comparisons are then made, where possible, between producing the product via the most competitive conventional route and via the proposed bioprocessing route. Next, qualitative information is gathered from industrial experts on the advantages and disadvantages of each product with respect to energy impacts, environmental quality, and economic competitiveness. Finally, engineering and economic evaluations are performed for the most promising candidates to assess the profitability of the bioprocessing route and to identify the research and development opportunities that have the greatest impact on energy savings, environmental quality, and economics. Forty chemicals and materials that could potentially be produced from renewable feedstocks were initially selected for evaluation by this methodology. From this, succinic acid was chosen for the first more detailed evaluation based on the initial screening results. The approach described in this article could be used by potential industrial producers to complement their forecasting of the technical and economic feasibility of producing chemicals and materials from renewable resources, and by researchers to identify opportunities for focused research and development.
TL;DR: Both accessibility to cellulases and the specific hydrolysis rate of substrates were found to be changed by chemical and physical pretreatment of the substrate.
Abstract: Adsorption of cellulases to cellulose is a critical step in the hydrolysis of cellulosic substrates. However, the importance of adsorption in determining the hydrolysis rate is unclear. The accessibility to cellulases and specific hydrolysis rates were measured for various substrates. No correlation was found between the amount of enzyme adsorbed and the initial hydrolysis rate for different substrates. Specific hydrolysis rates were found to differ among substrates. Furthermore, both accessibility to cellulases and the specific hydrolysis rate of substrates were found to be changed by chemical and physical pretreatment of the substrate.
TL;DR: In this paper, the transesterification method was applied to crude safflower seed oil of Turkish origin using methanol, and a significant improvement was observed in viscosity and other physical properties with the ester product compared to the parent vegetable oil.
Abstract: The primary problems associated with the use of pure vegetable oils as fuels in compression ignition (Diesel) engines are caused by high fuel viscosity. Transesterification of the oil with short-chain alcohols (such as methanol or ethanol) to corresponding fatty esters is the most promising solution to the high-viscosity problem. In this work, the transesterification method was applied to crude safflower seed oil of Turkish origin using methanol. The variables affecting the monoester yield, such as:
were investigated. In the presence of 1.0 wt% KOH as the reaction catalyst, 97.7% ester yield was achieved within 18 min at a reaction temperature of 69 ± 1‡C using 1:7 vegetable oil-alcohol molar ratio. A significant improvement was observed in viscosity and other physical properties with the ester product compared to the parent vegetable oil. ASTM fuel properties of the methyl ester product were in accordance with those obtained for commercial Grade No.2-D diesel fuel.
TL;DR: A novel two-temperature dilute-acid prehydrolysis of hybrid poplar xylan that exploits the xylan biphasic kinetics at moderate temperatures is described, resulting in improvements in both yield of xylose equivalents and ethanol production level and rate.
Abstract: A novel two-temperature dilute-acid prehydrolysis of hybrid poplar xylan that exploits the xylan biphasic kinetics at moderate temperatures is described. A lower temperature (140‡C) is applied to hydrolyze the easily hydrolyzable xylan, and a higher temperature (170‡C) is subsequently applied to hydrolyze the remaining xylan. Using a bench-scale percolation reactor, yields of soluble xylose expressed in monomeric xylose equivalents as high as 92% of theoretical have been achieved with only 2% of the xylan being degraded to furfural. The lignocellulosic substrate produced from the pretreatment is readily converted to ethanol at a yield of 94% of theoretical via a simultaneous saccharification and fermentation process in 48 h. In terms of both yield of xylose equivalents and ethanol production level and rate, these improvements are far superior to those previously reported using a single-temperature dilute-acid pretreatment.
TL;DR: A. cellulolyticus E1 was found to exhibit striking synergism with a fungal cellobiohydrolase (Trichoderma reesei CBH I) in the saccharification of microcrystalline cellulose.
Abstract: A new thermostable endoglucanase,Acidothermus cellulolyticus E1, and another bacterial endoglucanase, E5 fromThermomonospora fusca, each exhibit striking synergism with a fungal cellobiohydrolase (Trichoderma reesei CBH I) in the saccharification of microcrystalline cellulose. In neither case did the ratio of endoglucanase to exoglucanase that demonstrated maximum synergism coincide exactly with the ratio that actually released the maximum quantity of soluble sugar for a given total cellulase loading. The difference between the two ratios, after significant hydrolysis of the substrate, was considerably larger in the case ofA. cellulolyticus E1. For both endoglucanase pairings with CBH I, the offset between the ratio for maximum synergism and the ratio for maximal soluble sugar production was found to be a function of digestion time.
TL;DR: A new strain of the fungus Beauveria bassiana Nov.
Abstract: A new strain of the fungusBeauveria bassiana Nov. EO-1 (ATCC 74037), which produces a red pigment in solid and liquid culture, has been isolated from an infected whitefly. The red pigment was extracted and has been identified by mass spectrometry as oosporein, a potent dibenzoquinone mycotoxin.
TL;DR: Experiments suggested that ESM is promising to use for the purpose of removal/recovery of metals and water pollution control.
Abstract: The egg shell membrane (ESM) is an intricate lattice network of stable and water-insoluble fibers with high surface area. ESM accumulates and eliminates various heavy metal ions from dilute aqueous solution with high affinity and in short contact time, depending on pH and characteristics of the individual ion. Under certain conditions, the level of precious ions, Au, Pt, and Pd accumulation approaches 55, 25, and 22% of dry wt of ESM, respectively. Also uranium uptake 30% of that of ESM. Experiments suggested that ESM is promising to use for the purpose of removal/recovery of metals and water pollution control.
TL;DR: The result in lipase stability suggests an application of lipases from Penicillium citrinum in detergents and other products that require a high stability at room temperature.
Abstract: A lipases (glycerol ester hydrolases E. C. 3.1.1.3) from a brazilian strain of Penicillium citrinum has been investigated. When the microorganism was cultured in the simple medium (1.0% olive oil and 0.5% yeast extract), using olive oil in as carbon source in the inocula, the enzyme extracted showed maximum activity (409 IU/mL). In addition, decrease of yeast extract concentration also reduces the lipase activity. Nevertheless, when yeast extract was replaced by ammonium sulfate, no activity was detected. Purification by precipitation with ammonium sulfate showed best activity in the 40-60% fraction. The optimum temperature for enzyme activity was found in the range of 34-37°C. However, after 30 min at 60°C, the enzyme was completely inactivated. The enzyme showed optimum at pH 8.0. The dried concentrated fraction (after dialysis and lyophilization) maintained its lipase activity at room temperature (28°C) for 8 mo. This result in lipase stability suggests an application of lipases from P. citrinum in detergents and other products that require a high stability at room temperature.
TL;DR: Reporter strains of bacteria were tested using soil samples from several sites near a leaking fuel oil storage facility and indicated that two soil samples were contaminated with both toluene (or xylene) and naphthalene.
Abstract: Reporter strains of bacteria were tested using soil samples from several sites near a leaking fuel oil storage facility. The reporter bacteria utilized the bioluminescentlux genes fromVibrio fischeri, which were transcriptionally fused to catabolic gene sequences. The catabolic genes of interest specified the degradation of toluene (from the TOL plasmid) and naphthalene (from the NAH7 plasmid and from a NAH plasmid recently isolated). The results indicated that two soil samples were contaminated with both toluene (or xylene) and naphthalene. These data were useful in describing the extent of contamination at the site.
TL;DR: In this paper, the production of L(+)-lactic acid using alginate immobilizedRhizopus oryzae in tapered-column fluidized-bed batch reactor was tested and simulated using the kinetic data taken independently in shake-flask cultures.
Abstract: The production of L(+)-lactic acid using alginate immobilizedRhizopus oryzae in tapered-column fluidized-bed batch reactor was tested and simulated using the kinetic data taken independently in shake-flask cultures. The data show saturation kinetics with substrate and product inhibitions in linear form. Analysis of the kinetic data gave kinetic constants:V
m, 11.04 g lactic acid/(L-bead. h);K
m, 20.9 g glucose/L; andK
i, 365 g glucose/L for lactic acid production. The product inhibition constant,K
p, was found to be 316 g lactic acid/L. The simulation results showed a good agreement with the experimental results when the initial lag phase was taken into account in the simulation model. Without the adjustment for the initial lag period, the kinetic model showed higher conversion. Starting with a glucose concentration of 150 g/L, it was possible to produce 73 g/L of L(+)-lactic acid in 44.5 h. The lactic acid yield was 64.8% by weight based on the amount of glucose consumed.
TL;DR: In this article, a 25-L working volume, upright cylindrical fermenter made of stainless steel was used to investigate cheese whey yeast fermentation for pollution potential reduction, and the effluent total and soluble chemical oxygen demand, total and volatile solids, and total Kjeldahl and ammonium nitrogen concentrations were significantly affected by the hydraulic retention time, air flow rate, and mixing speed.
Abstract: A 25-L working volume, upright cylindrical fermenter made of stainless steel was used to investigate cheese whey yeast fermentation for pollution potential reduction. The effluent total and soluble chemical oxygen demand, total and volatile solids, and total Kjeldahl and ammonium nitrogen concentrations were significantly affected by the hydraulic retention time, air flow rate, and mixing speed. The system removal efficiencies were 15.90-58.61%, 25.20-69.33%, 12.43-49.90%, 9.22-51.77%, 1.66-10.06%, and 54.82-72.22% for total chemical oxygen demand, soluble chemical oxygen demand, total solids, volatile solids, total Kjeldahl nitrogen, and ammonium nitrogen, respectively, depending on the hydraulic retention time, air flow rate, and mixing speed used.
TL;DR: In this paper, the presence of zinc ions in the cellulose gels enhanced the rate of hydrolysis and glucose yield and the evidence obtained from X-ray diffraction, iodine absorption experiments; and Nuclear Magnetic Resonance spectra analysis suggested the presence presence of Zinc-cellulose complex after Avicel was treated with zinc chloride.
Abstract: Cellulose gel with < 10% of crystallinity was prepared by treatment of microcrystalline cellulose, Avicel, with zinc chloride solution at a ratio of zinc chloride to cellulose from 1.5 to 18 (w/w). The presence of zinc ions in the cellulose gels enhanced the rate of hydrolysis and glucose yield. The evidence obtained from X-ray diffraction, iodine absorption experiments; and Nuclear Magnetic Resonance spectra analysis suggested the presence of zinc-cellulose complex after Avicel was treated with zinc chloride. Zinc-cellulose complex was more susceptible to hydrolysis than amorphous cellulose. Under the experimental condition, cellulose gels with zinc ions were hyrolyzed to glucose with 95% theoretical yield and a concentration of 14% (w/v) by cellulases within 20 h. The same gel was hydrolyzed by acid to glucose with 91.5% yield and a concentration of 13.4% (w/v).
TL;DR: In this paper, an integrated approach to produce protein and fermentable sugars from one herbaceous species, Coastal Bermudagrass (CBG), was proposed, where the ammonia fiber explosion (AFEX) process made possible over 90% conversion of cellulose and hemicellulose to simple sugars.
Abstract: The herbaceous crops that may provide fermentable carbohydrates for production of fuels and chemicals also contain 10–20% protein. Protein coproduction with biomass-derived fuels and chemicals has important advantages: (1) food and fuel production can be integrated, and (2) protein is a high-value product that may significantly improve overall process economics. We report the results of an integrated approach to producing protein and fermentable sugars from one herbaceous species, Coastal Bermudagrass (CBG). The ammonia fiber explosion (AFEX) process makes possible over 90% conversion of cellulose and hemicellulose to simple sugars (about 650 mg reducing sugars/g dry CBG) at 5 IU cellulase/g vs < 20% conversion for untreated CBG. The AFEX treatment also improves protein extraction from CBG; over 80% protein recovery is possible from AFEX-treated CBG vs about 30% recovery from untreated CBG.
TL;DR: Although the alkali-treated residue derived from steam-treated eucalyptus did not provide good cellulosic substrates recovery, subsequent alkaline peroxide treatment of this residue dramatically enhanced cellulase recycling efficiency.
Abstract: The recovery and recycling of cellulases during fed-batch hydrolysis of cellulosic substrates derived from SO2-impregnated steamtreatedEucalyptus viminalis chips was examined An initial enzyme loading of 10 FPU and 25 CBU g−1 cellulose was shown to be effectively recovered and recycled to hydrolyse seven consecutive batches of pretreated substrate at a 5% (w/w) cellulose concentration Although the alkali-treated residue derived from steam-treated eucalyptus did not provide good cellulase recovery, subsequent alkaline peroxide treatment of this residue dramatically enhanced cellulase recycling efficiency A glucose production rate of 261 ± 17 mg mL−1 d−1 was obtained for seven consecutive days, with an elapsed time of 24 h between each recycling step, without any requirement for further addition of cellulases after the first hydrolysis step However, a considerable loss of both protein and enzymatic activity was observed throughout the experiment In preliminary work, an excess of cellobiase activity was added at the beginning of every new hydrolysis step to avoid cellobiose accumulation in the reaction mixture This was shown to be unnecessary when an additional step of ultrafiltration was used to recover and recycle the cellobiase activity present in the hydrolysates
TL;DR: This article brings together all of the kinetic data on catalytic antibodies available in the published literature at the time of writing (September, 1993) so that they can be analyzed for any significant trends that arise from relating the structure of the transition-state analog/hapten to the type and efficiency of the catalytic antibody activity elicited.
Abstract: This article brings together all of the kinetic data on catalytic antibodies available in the published literature at the time of writing (September, 1993). The data have been presented so that they can be analyzed for any significant trends that arise from relating the structure of the transition-state analog/hapten to the type and efficiency of the catalytic antibody activity elicited.