Showing papers in "Biotechnology Techniques in 1988"
TL;DR: In this article, techniques for preparing four kinds of hydrogel membrane capsules are described, where the material being encapsulated remains in its original environment in an aqueous suspension, and capsule characteristics such as size, membrane thickness, pore size and surface charge can be controlled over a wide range.
Abstract: SUMMARY Techniques for preparing four kinds of hydrogel membrane capsules are described. In the present process the material being encapsulated remains in its original environment in an aqueous suspension. Also, capsule characteristics such as size, membrane thickness, pore-size and surface charge can be controlled over a wide range.
84 citations
TL;DR: Alginate solutions with two different M/G (mannuronic acid/guluronic acids) ratios were added dropwise to SrCl2 and BaCl2 solutions.
Abstract: Alginate solutions with two different M/G (mannuronic acid/guluronic acid) ratios were added dropwise to SrCl2 and BaCl2 solutions. The low M/G ratios (0.27) Sr− and Ba-alginate gel beads were more chemically and physically stable in electrolyte solutions than conventional Ca− alginate gel beads. These gel beads with immobilized yeast cells had normal ethanol productivities.
47 citations
TL;DR: A selection of dyes for tracer studies in bioreactors, specially for wastewater treatment, is presented in this article, which shows no adsorption on air or biomass, stability in time, good solubility and no color change between pH 6.5 to 8.5.
Abstract: A selection of dyes for tracer studies in bioreactors, specially for wastewater treatment, is presented. Substances that showed no adsorption on air or biomass, stability in time, good solubility and no color change between pH 6.5 to 8.5, were: bromocresol green, bromophenol blue, dextran blue, eosin Y and mordant violet. Consequently they seem to be adequate for common biochemical engineering processes. In addition, dyes that showed some limitations, but may be employed in special cases, were: bromophenol red and phenol red (color change between pH 5.0 to 6.8 and 6.8 to 8.4 respectively) and methylene violet Bernsthen (low spectrophotometric response).
44 citations
TL;DR: This article measured physical properties for three PEG-maltodextrin two-phase systems and demonstrated their bioseparation capabilities by extracting alcohol dehydrogenase from yeast extracts with a PEG bound textile dye.
Abstract: Several low-cost maltodextrins form two liquid phases with polyethylene glycol (PEG) in aqueous solution. We have measured physical properties for three PEG-maltodextrin two-phase systems and demonstrated their bioseparation capabilities by extracting alcohol dehydrogenase from yeast extracts with a PEG bound textile dye.
42 citations
TL;DR: A procedure for the measurement of fungal and bacterial α-amylase in crude culture filtrates and commercial enzyme preparations is described, which employs end-blocked (non-reducing end)p-nitrophenyl maltoheptaoside in the presence of amyloglucosidase and α-glucOSidase.
Abstract: A procedure for the measurement of fungal and bacterial α-amylase in crude culture filtrates and commercial enzyme preparations is described. The procedure employs end-blocked (non-reducing end)p-nitrophenyl maltoheptaoside in the presence of amyloglucosidase and α-glucosidase, and is absolutely specific for α-amylase. The assay procedure is simple, reliable and accurate.
41 citations
TL;DR: In this article, an integrated computerized control system consisting of temperature and moisture sensors, a variable relative humidity air stream and water sprayers was used to control temperature and humidity in the solid substrate fermentation of extruded corn withRhizopus ligosporus in a 15 l rotary drum fermenter.
Abstract: An integrated computerized control system, consisting of temperature and moisture sensors, a variable relative humidity air stream and water sprayers was used to control temperature and moisture in the solid substrate fermentation of extruded corn withRhizopus
oligosporus in a 15 l rotary drum fermenter. Dry air was blown through the substrate to force evaporative cooling, balanced by spraying of cold water to maintain constant moisture.
39 citations
TL;DR: The resonance nozzle immobilization technique was tested with thermo-hardening hydrogels (agar, gellan and κ-carrageenan) and compared with the conventional needle technique, proving to give satisfactory results, although the retention of respiration activity was generally lower than obtained with the needle technique.
Abstract: The resonance nozzle immobilization technique was tested with thermo-hardening hydrogels (agar, gellan and κ-carrageenan) and compared with the conventional needle technique. After nozzling the warm gel solution, the formed droplets were caught in an ice-cold two-phase system consisting of an organic solvent (n-butylacetate, hexane or nonane) as top phase, in which gelling occurred, and aqueous medium as bottom phase. The cells used were yeast cells (Saccharomyces cerevisiae), bacterial cells (Mycobacterium aurum L1), plant cells (Tagetes minuta) and insect cells (Spodoptera frugiperda). The retention of the respiration activity was used as a criterion for the suitability of the conditions applied. The relatively polar solvent n-butylacetate with the low log P value gave the poorest activity retention, which is in agreement with experimentally validated theory. For all gels, the resonance nozzle technique proved to give satisfactory results, although the retention of respiration activity was generally lower than obtained with the needle technique.
31 citations
TL;DR: In this article, a polymerization of pyrrole in aqueous KCl solution containing glucose oxidase produces adherent films at platinum electrode surface, which can determine glucose in the range 0 to 100mm.
Abstract: Electrochemical polymerization of pyrrole in aqueous KCl solution containing glucose oxidase produces adherent films at platinum electrode surface. Such coated electrodes are prepared in 20 min and can determine glucose in the range 0 to 100mm. The useful lifetime of the electrode is 85 assays. Its stability is at least 75 days under storage in PBS at 4°C.
26 citations
TL;DR: A dairy by-product was used in cell line cultures as a replacement for fetal calf serum to stimulate DNA synthesis in human and mouse 3T3 fibroblast and hybridoma cultures and allow hybridoma proliferation in the long term using only 0.5% FCS.
Abstract: A dairy by-product was used in cell line cultures as a replacement for fetal calf serum (FCS). Various fractions were prepared from whey. All fractions have the ability to stimulate DNA synthesis in human and mouse 3T3 fibroblast and hybridoma cultures. They also allow hybridoma proliferation in the long term using only 0.5% FCS. In these latter experiments, heated and ultrafiltered fractions were more effective than 10% fetal calf serum.
24 citations
TL;DR: In this paper, a model solid substrate consisting of cassava starch and other nutrients embedded in kappa-carrageenan was developed, and a suitable fermentation system and analytical techniques were also developed to cope with the constraints imposed by solid state fermentation.
Abstract: A model solid substrate was developed, consisting of cassava starch and other nutrients embedded in kappa-carrageenan. A suitable fermentation system and analytical techniques were also developed to cope with the constraints imposed by solid-state fermentation.
17 citations
TL;DR: An improved technique of protoplast regeneration and a general procedure of transfection and plasmid transformation are described in Clostridium acetobutylicum.
Abstract: An improved technique of protoplast regeneration and a general procedure of transfection and plasmid transformation are described inClostridium acetobutylicum. Frequencies of 104–105 transfectants/transformants per μg of DNA were easily achieved.
TL;DR: Xanthan concentration and molecular weight distribution are determined by size exclusion chromatography in the fermentation medium after dilution and cell removal by centrifugation because the analysis is rapid enough for process control.
Abstract: Xanthan concentration and molecular weight distribution are determined by size exclusion chromatography in the fermentation medium after dilution and cell removal by centrifugation. The analysis is rapid enough for process control. During a batch fermentation, the average molecular weight is found to be in the range of 7.2–9.3·106 g/mole and to run through a maximum.
TL;DR: It appears that redox potential in conjunction with fluorescence measurements are of utility in studying extra- and intracellular reduction states, particularly in the microaerobic regime.
Abstract: Transient experiments were performed during a batch fermentation ofCorynebacterium glutamicum ATCC 14296 in which the flow of air to the reactor was cut off. The fluorescence of the culture was observed to vary linearly with the culture redox potential during the transient. This observation was made below the sensitivity limit of a dissolved oxygen probe. It appears that redox potential in conjunction with fluorescence measurements are of utility in studying extra- and intracellular reduction states, particularly in the microaerobic regime.
TL;DR: A simple procedure based on differential sensitivity to a given panel of “killer yeasts” allows the discrimination of strains within the species K. lactis and K. marxianus.
Abstract: A simple procedure based on differential sensitivity to a given panel of “killer yeasts” allows the discrimination of strains within the speciesK. lactis andK. marxianus. The proposed method was found to be reproducible, readily discriminatory, and easy to perform without specialized equipment. All strains within the species are characterized by a specific, individual sensitivity pattern (killer formula).
TL;DR: In this article, a method for measuring KL a in a solid state medium is proposed, which allows to study the influence of air inflow rate and dry matter percentage of the medium on the oxygen volumetric mass transfer coefficient.
Abstract: A convenient method for measuring KL a in a solid state medium is proposed. Due to the particular nature of the substrate used in solid state fermentation, different modifications of the sulfite oxidation method have been necessary. This first approach allows to study the influence of air inflow rate and dry matter percentage of the medium on the oxygen volumetric mass transfer coefficient.
TL;DR: The immobilization of enzymes and microbial cells within insolubilized gelatin involves both physical entrapment and covalent crosslinking, each one playing its role.
Abstract: The immobilization of enzymes and microbial cells within insolubilized gelatin involves both physical entrapment and covalent crosslinking, each one playing its role. The effect of this dual type of bonding on the kinetic parameters and activity yield of three enzymes (acid phosphatase, invertase and α-glucosidase) and of whole microbial cells belonging to three yeast species (Saccharomyces cerevisiae,Candida utilis andKluyveromyces marxianus) have been investigated.
TL;DR: Using Gibbs Energies of compounds, as well as Gibbs Energy changes and equilibrium constants of biochemical reactions, the contributions of functional groups to the Gibbs Energy (in aqueous solution, temperature 25°C, and pH=7) have been estimated as discussed by the authors.
Abstract: Using Gibbs Energies of compounds, as well as Gibbs Energy changes and equilibrium constants of biochemical reactions, the contributions of functional groups to the Gibbs Energy (in aqueous solution, temperature 25°C, and pH=7) have been estimated. These contributions allow the estimation of the Gibbs Free Energy and the equilibrium constant of a biochemical reaction, given the structure of the reactants and products.
TL;DR: In this article, the enantioselective hydrolysis of racemic 4-acetoxy-cyclopentenone by immobilized enzymes is described, which combines the specific enzymatic reaction with a selective transport through the organic phase.
Abstract: The enantioselective hydrolysis of racemic 4-acetoxy-cyclopentenone by immobilized enzymes is described. Liquid membrane emulsions were used to encapsulate the enzyme. This technique combines the specific enzymatic reaction with a selective transport through the organic phase. The product (−)-4-hydroxy-cyclopentenone was produced with an enantiomeric excess of 82%. The immobilization techniques and all reaction steps, as well as a mathematical model for the complete process are discussed in this report.
TL;DR: Separating fungi from cellulose fibres by a layer of agar or by filters showed that cell-fibre contact is not necessary for cellulose degradation, and such degradation is clearer when contact is prevented.
Abstract: Cellulolytic activity of four fungal species growing on solid medium containing acid-swollen cellulose could be detected much more easily if fungal growth was partly inhibited by the detergent Triton X-100. The dye, aniline blue-black, did not affect growth but increased the sensitivity of detection of cellulolytic activity of both fungi and bacteria. Separating fungi from cellulose fibres by a layer of agar or by filters showed that cell-fibre contact is not necessary for cellulose degradation. Such degradation is clearer when contact is prevented.
TL;DR: In this article, the origin of vinegars obtained by bacterial or chemical oxidation of ethanol resulting from the fermentation of various sugars is identified by a new method based on NMR determination of site specific deuterium/hydrogen ratio in acetic acid.
Abstract: The origin of vinegars obtained by bacterial or chemical oxidation of ethanol resulting from the fermentation of various sugars is identified by a new method based on NMR determination of site specific deuterium/hydrogen ratio in acetic acid.
TL;DR: In this paper, a new capillary inlet system was used with a magnetic sector mass spectrometer to analyse headspace gas from air-sparged aqueous solutions of methanol and ethanol.
Abstract: A new capillary inlet system was used with a magnetic sector mass spectrometer to analyse headspace gas from air-sparged aqueous solutions of methanol and ethanol. The system responded to pulse additions within 2 minutes and gave ≥90% of equilibrium response after 10 minutes. No memory effects or hysteresis were observed. Signal to concentration ratio was linear with alcohol concentrations up to 5 g/L. Liquid ethanol concentration in aerobic yeast fermentation was followed successfully by on-line headspace gas analysis.
TL;DR: A linear relationship was found between cell concentration and culture fluorescence during in the early exponential growth phase and accumulation of a metabolite in the culture broth affects fluorescence by NADH consumption and inner filter effects.
Abstract: The fluorescence of a batch culture ofPseudomonas putida grown on phenol was investigated. A linear relationship was found between cell concentration and culture fluorescence during in the early exponential growth phase. Accumulation of a metabolite in the culture broth affects fluorescence by NADH consumption and inner filter effects. The fluorescence is also affected by changes in the metabolic activity of the cells. These effects during the course of the fermentation are discussed.
TL;DR: This study reports on the degradation of lignocellulose by three species of actinomycetes, Streptomyces cyaneus,Thermomonospora mesophila andActinomadura sp.
Abstract: This study reports on the degradation of lignocellulose by three species of actinomycetes,Streptomyces cyaneus,Thermomonospora mesophila andActinomadura sp. Control studies showed that there was a release of soluble material, a result of the aqueous extraction of the straw and that these materials were rapidly utilized by the organisms at the onset of growth. HPLC analysis was able to identify the water soluble products of radioactive and nonradioactive substrates from culture supernatants and in cell-free extracts. It is concluded that the products and therefore the mechanism of lignocellulose solubilization is quite different for each of the organisms.
TL;DR: A fast 4-step isolation procedure for β-D-galactosidase from E. coli has been developed: cell disruption, two-stage aqueous two-phase extraction and ultrafiltration, achieving a 60-fold purification of the enzyme.
Abstract: A fast 4-step isolation procedure for β-D-galactosidase from E coli has been developed: cell disruption, two-stage aqueous two-phase extraction and ultrafiltration A 60-fold purification of the enzyme with a total yield of 75% was achieved
TL;DR: Aspergillus niger LCF No9 synthesizes large amounts of a semi-alkaline protease highly active on Benzoyl arginine p-nitroanilide (BAPNA) that is likely to find industrial use.
Abstract: Aspergillus niger LCF No9 synthesizes large amounts of a semi-alkaline protease highly active on Benzoyl arginine p-nitroanilide (BAPNA) that is likely to find industrial use. An industrial-grade enzyme of around 80% purity was prepared and a reference enzyme was obtained in high yield from the industrial product by ultrafiltration and HPIEC on a mono Q column. The industrial-grade enzyme was produced on a pilot scale with a yield of 0.52% of medium solid starting material by adsorption on CM-Sephadex A50, precipitation with acetone at −30°C, ion-exchange chromatography on DEAE-Sepharose and diafiltration.
TL;DR: The use of chitosan fibers as a matrix for immobilizing hybridoma cells was investigated and the viability of the cells was found to be unaffected by the presence of ch itosan in culture.
Abstract: The use of chitosan fibers as a matrix for immobilizing hybridoma cells was investigated. Optimal cell entrapment within fibrous chitosan occurred at pH values below 7.2. Chitosan fibers were found to be more effective than chitosan beads in the occlusion of the hybridoma cells. Maximum total cell concentrations of 5 to 5.8 × 106 cells/mL were obtained in the chitosan fractions of cultures containing 25% to 50% chitosan volume fractions. The viability of the cells was found to be unaffected by the presence of chitosan in culture.
TL;DR: Ionic HPLC is a novel technique used to determine more easily mineral ions consumptions during fermentations during fermentation.
Abstract: Ionic HPLC is a novel technique used to determine more easily mineral ions consumptions during fermentations.
TL;DR: A simple assay based on the enzymatic release of stained cleavage products originating from dyed substrates such as different celluloses, mannan and xylan, diffusing from an upper into a lower agar layer became applicable to various species of basidiomycete fungi.
Abstract: A simple assay is described for the quantitative measurement of cellulase and hemicellulase activities. It is based on the enzymatic release of stained cleavage products originating from dyed substrates such as different celluloses, mannan and xylan, diffusing from an upper into a lower agar layer. The amount of cleavage products is assessed by direct absorbance measurement in the agar tubes employing an ordinary filter photometer. The method proved to be applicable to various species of basidiomycete fungi.
TL;DR: Three methods, the dynamic one, the balance one, and the biological one, were used for KLa estimation in the culture of Aspergillus niger, and big differences between the values obtained were observed.
Abstract: Three methods, the dynamic one, the balance one, and the biological one, were used for KLa estimation in the culture ofAspergillus niger. Big differences between the values obtained by the dynamic and the other two methods were observed. The mathematical model including the diffusion of oxygen into the pellets can offer an explanation.
TL;DR: The role of several culture conditions is described and its values determined for the maximum yeast production in mixed cultures of Aspergillus oryzae and Rhodotorula glutinis.
Abstract: By means of an experimental factorial design the role of several culture conditions is described and its values determined for the maximum yeast production in mixed cultures ofAspergillus oryzae andRhodotorula glutinis.