The role, basic concepts and development of bioprocess engineering have been presented. Biochemical engineers have always served as a bridge between discoveries involving enzymes, cells and biomass at the lab scale to implementation of valuable bioproducts on the commercial scale. Biochemical engineering discipline was initiated focusing on problems concerning bioreactor design and the optimisation and the purification of natural products. Nowadays, this discipline is a field undergoing a rapid change and diversification. Key concepts in transport phenomena, kinetics and thermodynamics, as well as proficiency in the application of mathematical tools in process modelling are used to bridge the gap between the intellectual potential of the gene to the manufacturing of industrial products.
The generalized anaerobic digestion model developed by the Task Group of IWA is discussed. The structured model includes multiple steps describing biochemical as well as physico-chemical processes. The biochemical steps include disintegration of a particulate substrate to carbohydrates, proteins and lipids, extracellular hydrolysis of these particulate biopolymers to sugars, amino acids, and long chain fatty acids, respectively, acidogenesis from sugars and amino acids to volatile fatty acids and hydrogen; acetogenesis of long chain - and volatile fatty acids to acetate , and separate methanogenesis steps from acetate and from hydrogen and carbon dioxide. The ADM1 is a powerful tool for predicting both steady state and dynamic behaviour of anaerobic digesters. The extensions and applications of the ADM1 model to simulate industrial scale anaerobic digestion processes are reviewed.
General problems of mass and energy balances of microbial growth are presented. The elemental mass balance and limits for biomass yield are discussed. Methods of the biomass yield prediction are reviewed. A concept of Gibbs energy of biooxidation is applied in the energy balance. Thermodynamic limits of microbial growth are discussed. A simple model of metabolism is described to present the structural approach to microbial growth balances.
Metabolic engineering is an integrating methodology of analysis and synthesis for improvement of flux distribution of metabolic pathways. It has two main aspects: modeling and analysis of metabolic networks to establish strategies for pathway engineering and actual molecular level engineering the pathway. Mathematical modeling is one of the key methodologies of metabolic engineering. The review presents the currently used metabolic modeling approaches. Metabolite balancing is the basis for analysis of metabolic flux and cell capability to form a targeted product. The use of isotope ? labeled substrates with nuclear magnetic resonance (NMR) and gas chromatography-mass spectrometry (GCMS) analyses of intracellular and extracellular metabolites enables determination of metabolic flux distribution. Metabolic Control Analysis (MCA) is a theoretical framework for investigation of control mechanism of metabolic network to identify key parameters influencing productivity. Kinetics models present a more detailed approach to simulate metabolic net behavior. Linear approximation of kinetic model, the so called (log)linear kinetics, is useful for modeling spatiotemporal variations of the net. The including of genetic regulation to metabolic models, the next step in the development of metabolism models, needs new methods of experimental approaches and mathematic and computational resources. Metabolic engineering is barely a decade old, but its significance is already widely recognized in the research-intensive biotechnology community and attracts great interest of industry.
Perfluorochemicals (fluorocarbons, PFCs) are the ones possible to use oxygen vector in biomedical sciences. Their structure, chemical and physical properties are fully described. The use of PFCs in medicine and biotechnology is presented. Possible areas of application of perfluorochemicals in biochemical engineering are discussed. Pure liquid or emulsified PFCs are used in the bioreactor cultures of microbial, plant or animal cells to improve the oxygen (or carbon dioxide) delivery with simultaneous reduction of hydrodynamic shear stress.
Methods of purification of chitin deacetylase are discussed. A two step method of purification of chitin deacetylase from mycelial extracts of the fungus Absidia orchidis by chromatography is presented. The crude enzyme extract was purified by a gel chromatography and then by ion exchange chromatography. Specific activity of purified enzyme was 12.3 U/mg and final purification degree was 147. The apparent molecular mass of the enzyme was 75 kDa. When O ? hydroxyethylated chitin (glycol chitin) was used as a substrate, the optimum pH for enzyme activity was 5,5 and the optimum temperature was 50?C.
Properties of microbial lipases important in practical applications are briefly described. Applications of lipases in wide branches of industry are presented. Potential fields of lipases applications are also discussed.
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