Showing papers in "Advances in Biochemical Engineering \/ Biotechnology in 1992"
TL;DR: This paper summarizes the developments in the applications of aqueous two-phase systems to biotechnology by reviewing the phase diagram and its characteristics, fundamentals of biomolecule partition, large-scale and multi-stage aqueously two- phase biomolecules purification, and extractive bioconversions.
Abstract: Over the past-thirty years, aqueous polymer two-phase technology has evolved, both experimentally and theoretically, into a separation science with many useful applications in biomolecule purification and bioconversion. This paper summarizes the developments in the applications of aqueous two-phase systems to biotechnology. The main topics to be considered are the phase diagram and its characteristics, fundamentals of biomolecule partition, large-scale and multi-stage aqueous two-phase biomolecule purification, and extractive bioconversions. The first topic involves a discussion of the thermodynamics of aqueous polymer two-phase formation and how it is influenced by such factors as polymer molecular weight and concentration, temperature, and salt type and concentration. Next, the theoretical and experimental aspects of biomolecule partition in aqueous two-phase systems will be discussed in light of the factors which influence biomolecule partition: polymer concentration and molecular weight; temperature; salt type and concentration; the addition of charged, hydrophobic and affinity derivatives. Having reviewed the fundamentals of phase diagram formation and biomolecule partition, the next two topics are applications of aqueous two-phase technology. The first set of applications involve the large-scale extraction of proteins using one to three equilibrium stages and multi-stage purifications using countercurrent distribution, liquid-liquid partition chromatography and continuous countercurrent chromatography. The second application, and very promising area for future aqueous two-phase technology, is the extractive bioconversion which permits the simultaneous production and purification of a biomolecule.
183 citations
TL;DR: A critical appraisal of the methods used to assess cellulase multiplicity is presented and the recent elucidation of the three-dimensional domain structure of cellulases, their active center, and the role of both in the hydrolysis of cellulose are dealt with.
Abstract: The filamentous fungus Trichoderma reesei is the predominant industrial producer of cellulolytic enzymes by secreting an enzyme system capable of degrading crystalline cellulose, which consists of several cellobiohydrolases, endoglucanases and β-glucosidases. All of these enzymes occur in multiple forms. A critical appraisal of the methods used to assess cellulase multiplicity is presented. By the aid of gene technology, advanced protein analytics and immunology, “true” isoenzymes and proteolytic fragments of all of these enzymes could be identified, and their structure and properties are described. Also, the recent elucidation of the three-dimensional domain structure of cellulases, their active center, and the role of both in the hydrolysis of cellulose are dealt with. Particular emphasis is presented on the differences in the enzymatic reaction mechanisms of cellobiohydrolase I and II, and their synergism.
112 citations
TL;DR: This review on enzymes from extreme thermophiles (optimum growth temperature greater than 65 degrees C) concentrates on their characteristics, especially thermostabilities, and their commercial applicability.
Abstract: This review on enzymes from extreme thermophiles (optimum growth temperature >65 °C) concentrates on their characteristics, especially thermostabilities, and their commercial applicability. The enzymes are considered in general terms first, with comments on denaturation, stabilization and industrial processes. Discussion of the enzymes subsequently proceeds in order of their E.C. classification: oxidoreductases, transferases, hydrolases, lyases, isomerases and ligases. The ramifications of cloned enzymes from extreme thermophiles are also discussed.
88 citations
TL;DR: Practical examples of bioproduction, such as histidine, lysine, and glutathione, as well as production of an enzyme, showed that the two-stage production process could be realized experimentally, thus demonstrating the validity of the method.
Abstract: A method for obtaining maximum production of the bioproduct in fed-batch cultures is explained, and its validity is demonstrated by experimental data. The approach is based on a model which describes the relationship between the specific production rate, ϱ. and specific growth rate, μ. Using a mathematical model, an optimal profile of the specific growth rate could then be obtained easily by the Maximum Principle. Finally, the optimal profile was realized by changing the feed rate of the substrate in a practical fed-batch culture. Practical examples of bioproduction, such as histidine, lysine, and glutathione, as well as production of an enzyme, showed that the two-stage production process could be realized experimentally, thus demonstrating the validity of the method.
82 citations
TL;DR: It is important to review the mathematical models described previously in the literature and the experimental data on which these models are built to have a detailed knowledge of the mechanisms underlying the growth process of filamentous fungi.
Abstract: Despite the considerable industrial importance of filamentous fungi there have been very few attempts to model the complex growth process of these microorganisms. With a new generation of high performance, computerized bioreactors and new analytical techniques it is possible to obtain the necessary experimental data for setting up reliable structured models describing the growth process of filamentous fungi. It is therefore interesting to review the mathematical models described previously in the literature and the experimental data on which these models are built. Only structured models are considered due to the complex metabolism of filamentous fungi and to the natural cellular structuring of the biomass, i.e. the biomass can be divided into different cell types.
68 citations
TL;DR: It is shown that the neural network estimator provides good on-line bioprocess state estimations and an efficient optimization algorithm which reduces the number of iterations required for convergence is proposed.
Abstract: The application of artificial neural networks to the estimation and prediction of bioprocess variables is presented in this paper. A neural network methodology is discussed, which uses environmental and physiological information available from on-line sensors, to estimate concentration of species in the bioreactor. Two case studies are presented, both based on the ethanol production by Zymomonas mobilis. An efficient optimization algorithm which reduces the number of iterations required for convergence is proposed. Results are presented for different training sets and different training methodologies. It is shown that the neural network estimator provides good on-line bioprocess state estimations.
62 citations
TL;DR: In this article, the potential bioethanol producing fungal strains, production of extracellular polysaccharases (cellulases and xylanases) and bioconversion of various carbohydrates are reviewed.
Abstract: The microbial production of ethanol and other solvents from renewable biomass is an attractive alternative to fuels and basic chemical feedstocks. Considerable efforts have been made in the past 10 years to improve the production of altenative fuel chemicals by various biological systems. Much current interest is focussed on the processes based on cellulosic and hemicellulosic feedstocks, the hydrolyzates of which contain a complex mixture of sugars. The technology to convert hexoses to ethanol is well established, however, conversion of pentoses and other sugars poses problems. Filamentous fungi belonging to the genera Fusarium, Monilia and Neurospora have been identified as potential organisms in recent years, that can convert cellulose directly to ethanol. Some species belonging to Fusarium, Mucor and Paecilomyces were also found to efficiently convert xylose to ethanol with high yields. Some fungal strains exhibited relatively higher ethanol and sugar tolerance. However, the major disadvantage with mycelial fungi for ethanol production is the slow bioconversion rate when compared to yeast. Potential bioethanol producing fungal strains, production of extracellular polysaccharases (cellulases and xylanases) and bioconversion of various carbohydrates are reviewed. The factors playing a significant role in determining culture variables and performance in lignocellulosic hydrolysate are discussed.
58 citations
TL;DR: A short review of the research in the past two years on immobilized whole cells, such as microbial, plant, and animal cells, is presented including a discussion from an engineering point of view.
Abstract: A short review of the research in the past two years (1990–1991) on immobilized whole cells, such as microbial, plant, and animal cells, is presented including a discussion from an engineering point of view. Recent works concerning the intraparticle mass transfer effect on immobilized microbial cells by the authors and their co-workers are also introduced. Finally, future prospects of the immobilized cell system will be discussed.
32 citations
TL;DR: Photosynthesis by microalgae would provide an efficient mechanism for the reduction of CO2, if well-designed photobioreactors could be constructed for the intensive cultivations and recent development in sensor technology are described.
Abstract: Biotechnological fixation of carbon dioxide (CO2) is described as a measure for reducing CO2 emissions. Photosynthesis by microalgae would provide an efficient mechanism for the reduction of CO2, if well-designed photobioreactors could be constructed for the intensive cultivations. Screening of microalgae which can grow well under high CO2 concentrations would also be necessary in order to establish biotechnological CO2 reduction systems. In addition, calcification and vegetation are discussed as mechanisms for reducing CO2 emissions. Environmental monitoring is significantly important for the understanding of global CO2 cycle, so that recent development in sensor technology are also described.
32 citations
TL;DR: This article begins by noting some of the recent advances in membrane technology such as new developments in membrane materials and fluid mechanics, followed by integration of membranes into both cellular and enzymatic reaction systems, and a review of established and emerging membrane separation processes.
Abstract: Synthetic membrane processes are being increasingly integrated into existing reaction, isolation and recovery schemes for the production of valuable biological molecules In many cases they are also replacing traditional unit processes The properties of membrane systems which are most often exploited for both upstream and downstream processing are their high surface area per unit volume, their permselectivity, and their potential for controlling the level of contact and/or mixing between two separate phases Advances in both membrane materials and module design/operation have led to better control of concentration polarization and membrane fouling While this article begins by noting some of the recent advances in membrane technology such as new developments in membrane materials and fluid mechanics, followed by integration of membranes into both cellular and enzymatic reaction systems, the primary focus is a review of established and emerging membrane separation processes Many examples referred to in this review underscore the potential for combining membranes and biological processes to good advantage We believe that this marriage has only just begun and that improvements in membrane materials and a better understanding of the fluid mechanics in membrane modules and of metabolic processes for reaction systems will lead to an even stronger synergism in the future
31 citations
TL;DR: The kinetics of regulated secretion in the context of a controlled secretion process is extensively analyzed and the choice of cell lines, expression systems, cell culture methods, and bioreactor configurations are discussed.
Abstract: Traditional industrial cell culture processes require extensive downstream product refining due to low product titer and purity in the spent growth medium. A controlled secretion process incorporating cells derived from endocrine or exocrine organs could potentially alleviate this processing burden by dynamically decoupling product recovery from cell growth and product biosynthesis. In addition, such specialized secretory cells may be uniquely capable of performing desirable post-translational processing of the secretory product. We briefly review the biology of regulated protein secretion as well as the biology and biochemistry of the signal transduction mechansims by which regulated systems respond to environmental stimuli. Drawing on these and other basic principles from cell biology and bioengineering, we describe the important features of a controlled secretion process. Among other issues we discuss the choice of cell lines, expression systems, cell culture methods, and bioreactor configurations. We extensively analyze the kinetics of regulated secretion in the context of a controlled secretion process. This discussion is illustrated with experimental results from two model cell lines, recombinant AtT-20 and βTC3, expressing recombinant human endocrine hormones or native murine insulin respectively.
TL;DR: Bioprocess automation is mandatory to boost biotechnology from an empirical discipline to a natural science and made more reproducible and predictable than generally expected by exploitation of modern high-tech biotechnology hard- and software.
Abstract: Bioprocess automation is mandatory to boost biotechnology from an empirical discipline to a natural science. Bioprocesses can be made more reproducible and predictable than generally expected by exploitation of modern high-tech biotechnology hard- and software.
TL;DR: Both somatic and gametophytic embryos of oil plants exhibit high capacities for storage lipid biosynthesis and accumulation in vitro compared to cultured plant cells, and the microspore-derived embryo system is recommended to both plant breeders and plant biochemists for the selection and multiplication of plants of superior quality.
Abstract: The biosynthesis of storage lipids in plant cell and embryo cultures is discussed in the light of their significance in the breeding of agriculturally important oil seed crops. After a short introduction to the biosynthesis of storage lipids, i.e. triacylglycerols and wax esters, this review covers the occurrence and biosynthesis of storage lipids in plant cell and embryo cultures. Plant cells in culture generally contain low levels of both unusual fatty acids and triacylglycerols indicating that these cells are quite different from cells of oil storage tissues. There are a few exceptions to this rule which demonstrate that induction of genes involved in the expression of fatty acid modification and triacylglycerol assembly is possible in plant cell cultures. Such biosynthetically active plant cells may be of particular interest in future studies of storage lipid assembly. Both somatic and gametophytic embryos of oil plants exhibit high capacities for storage lipid biosynthesis and accumulation in vitro compared to cultured plant cells. Above all, the microspore-derived embryo system is recommended to both plant breeders and plant biochemists for the selection and multiplication of plants of superior quality.
TL;DR: The goal of this chapter is to provide practical strategies for large scale separations by gradient elution chromatography by developing a detailed model that can precisely predict the band position, profile and width at various gradient concentrations, gradient periods, flowrates, and column lengths.
Abstract: The goal of this chapter is to provide practical strategies for large scale separations by gradient elution chromatography. A detailed model has been developed for gradient elution systems considering interference effect, longitudinal diffusion, film mass transfer, intraparticle diffusion, mixing mechanism of the mobile phases, Langmuir-type adsorption and desorption kinetics. This detailed model can be solved by an efficient and robust numerical procedure. Hence, the optimizaton strategy of gradient elution has been developed through the calculation using this detailed model. This detailed model can precisely predict the band position, profile and width at various gradient concentrations, gradient periods, flowrates, and column lengths, in fair agreement with the experimental results. As a result of optimization, an optimal column length may exist. All the input parameters in this model have been either experimentally measured or estimated through empirical correlations. An alternative instrument for large-scale production using gradient elution has been suggested compared with conventional gradient elution instrument. The tolerance of the gradient elution processes to the fluctuation of input parameters has also been discussed.
TL;DR: The development of non-equilibrium immunoassays from a manually operated flow injection system to a completely computerized system for sample analysis as well as calibration and data evaluation is discussed.
Abstract: Immunoanalysis for process control is reviewed. The development of non-equilibrium immunoassays from a manually operated flow injection system to a completely computerized system for sample analysis as well as calibration and data evaluation is discussed. Several other approaches in using immunochemistry in biosensors for process control are discussed. The fact that reuse of antibodies raises specific demands on their properties is discussed. Even if the area is young, much progress has been achieved and one can foresee an interesting future development of the area.
TL;DR: The developments, potentials, and applications of novel purification procedures based on the affinity interaction between complementary molecules, as well as some common procedures by which ligands can be covalently immobilized to water-soluble or insoluble matrices are described.
Abstract: Novel purification processes have been developed, based on the affinity interaction between complementary molecules, to circumvent the difficulties associated with affinity chromatography. Depending upon the procedure used for isolating the ligand-ligate complex, the process can be termed affinity ultrafiltration, affinity partitioning or affinity precipitation. This review describes the developments, potentials, and applications of such purification procedures. Emphasis is also placed on the type and choice of affinity ligands as well as some common procedures by which ligands can be covalently immobilized to water-soluble or insoluble matrices. Finally, the problems and challenges encountered by such novel purification procedures are presented and discussed.
TL;DR: The research in Biotechnology is an important element for the competitive environment of European bioindustrial activities and the evolution of the Biotechnology programmes in the European Community is presented.
Abstract: The research in Biotechnology is an important element for the competitive environment of European bioindustrial activities. In this article the evolution of the Biotechnology programmes in the European Community is presented.
TL;DR: A part of the Japanese human genome project has resulted in the development of a world original human genome analysis system, which is described in the paper.
Abstract: A part of the Japanese human genome project has resulted in the development of a world original human genome analysis system. Circumstances of the project, objective, design concept, and constitution of the system are described in the paper.