江南大学发酵工程研究生面试英语翻译材料_62256_发酵工程江南大学

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[1] Industrial biotechnology, also known as white biotechnology, is the application of modern biotechnology to the sustainable production of chemicals, materials, and fuels from renewable sources, using living cells and/or their enzymes.This field is widely regarded as the third wave of biotechnology, distinct from the first two waves(medical or red biotechnology and agricultural or green biotechnology).Much interest has been generated in this field mainly because industrial biotechnology is often aociated with reduced energy consumption, greenhouse gas emiions, and waste generation, and also may enable the paradigm shift from foil fuel-based to bio-based production of value-added chemicals.***************************************************************************************************** [2] In aerobic bioprocees, oxygen is a key substrate employed for growth, maintenance and in other metabolic routes, including product synthesis.Due to its low solubility in broths, which are usually aqueous solutions, oxygen must be continuously provided by a gas phase, and thus the knowledge of oxygen transfer rate(OTR)is needed for bioreactor design and scale-up.The concentration of diolved oxygen in the broth, a suspension of respiring microorganisms, depends on the OTR from the gas to the liquid phase, and on the rate of its consumption by the microorganism, the oxygen uptake rate(OUR).***************************************************************************************************** [3] An immobilized enzyme is an enzyme that is attached to an inert, insoluble material such as calcium alginate(produced by reacting a mixture of sodium alginate solution and enzyme solution with calcium chloride).This can provide increased resistance to changes in conditions such as pH or temperature.It also allows enzymes to be held in place throughout the reaction, following which they are easily separated from the products and may be used again—a far more efficient proce and so is widely used in industry for enzyme catalysed reactions.An alternative to enzyme immobilization is whole cell immobilization.***************************************************************************************************** [4] The bioreactor is the heart of any biochemical proce in which enzymes, microbial, mammalian or plant cell systems are used for manufacture of a wide range of useful biological products.To design a bioreactor, some objectives have to be defined.The decisions made in the design of the bioreactor might have a significant impact on overall proce performance.Knowledge of reaction kinetics is eential for understanding how a biological reactor works.Other areas of bioproce engineering such as ma and energy balances, mixing, ma transfer and heat transfer are also required.***************************************************************************************************** [5] One of the most important tools for industrial biotechnology is protein engineering.More often than not, a wild-type enzyme discovered in nature is not suitable for an industrial proce.There is a need to engineer and optimize enzyme performance in terms of activity, selectivity on non-natural substrates, thermostability, tolerance toward organic solvents, enantioselectivity, and substrate/product inhibition in order for the enzymatic proce to be commercially viable.***************************************************************************************************** [6] As product purification is an eential part of the bioproce, it is also evident that the development and optimization of this part has to be performed in an integral way together with other key elements like biotransformation, fermentation or biocatalyst development.Changes in the bioproce itself or in the reaction conditions like pH, temperature and solvent, can have a decisive influence on the crystallization, phase separation, extraction or adsorption behavior

of

product

and

impurities.The

combination

of fermentation/biotransformation with in situ recovery techniques continues to be of much importance.***************************************************************************************************** [7] The main goal of metabolic engineering is to improve the metabolic phenotype through genetic modifications.Most of the recent approaches to metabolic engineering have aimed to improve a particular biosynthetic capacity through engineering of the target pathway based on rational aumptions for its improvement.The resulting phenotypes are, however, often suboptimal and unsatisfactory due to the distant effects of genetic modifications or unknown regulatory interactions.It is therefore strongly desirable to take into account the overall metabolic regulation mechanism in metabolic engineering.Metabolic regulation may occur either at the enzyme level or at the gene level.***************************************************************************************************** [8] Great efforts have been made in the last decade to identify genes and pathways relevant to cells enhancing productivity, figure out the metabolic bottlenecks, understand the mechanism of protein synthesis, develop better nutrients and media formulation, increase growth rate, and design procees with the aim to increase overall productivity.New technologies have recently become available, which allow a thoroughly high throughput aement of changes at gene(genomics)and protein(proteomics)levels involved in determining productivity in different environmental conditions, and establish functional relationships between cellular organization and productivity.***************************************************************************************************** [9] The oxygen transfer rate(OTR)in a bioreactor depends on the liquid side ma transfer coefficient, kL, the total specific surface area available for ma transfer, a, and the driving force in terms of concentrations.Since the two parameters, kL and a, can not be measured easily individually, they are usually lumped together as one single parameter called volumetric ma transfer coefficient, kLa.The available information on kLa in bioreactors is extensive.Many empirical correlations are proposed for kLa estimation.***************************************************************************************************** [10] A fed-batch is a biotechnological batch proce which is based on feeding of a growth limiting nutrient substrate to a culture.The fed-batch strategy is typically used in bio-industrial procees to reach a high cell density in the bioreactor.Mostly the feed solution is highly concentrated to avoid dilution of the bioreactor.The controlled addition of the nutrient directly affects the growth rate of the culture and allows to avoid overflow metabolism(formation of side metabolites, such as acetate for Escherichia coli, lactic acid in cell cultures, ethanol in Saccharomyces cerevisiae), oxygen limitation(anaerobiosis).***************************************************************************************************** [11] Solid-state fermentation(SSF)has long been applied to the food industry.SSFs are procees carried out with microbes growing on nutrient impregnated solid substrate with little or no free water.SSF can be directly carried out with abundant low-cost biomaterials(starch, cellulose, lignin, hemicellulose, chitin, etc.)with minimal or no pretreatment, and thus is relatively simple, uses le energy than submerged fermentation(SmF), and can provide unique microenvironments conducive to microbial growth and metabolic activities.Currently, SSF is undergoing a renewed surge of interest, primarily because of the opportunities that SSF affords for increased productivity as compared to SmF.***************************************************************************************************** [12] Fermentation broths are complex, aqueous mixtures of cells, comprising soluble extracellular, intracellular products and any unconverted substrate or unconvertible components.Recovery and extraction of product is important in bioproce engineering.In particular, separation is a useful technique;it depends on product, its solubility, size of the proce, and product value.Purification of high-value pharmaceutical products using chromatography such as hormones, antibody and enzymes is expensive and difficult to scale up.The neceary steps to follow a specific proce depend on the nature of the product and the characteristics of the fermentation broth.***************************************************************************************************** [13] Sterilisation is the action of eliminating microorganisms from a medium.Sterility is the absence of any detectable and viable microbes in a culture medium or in the gas phase.Sterilisation is a proce that destroys all living organisms, spores and viruses in a preurised veel at high temperature.In the food and dairy industries, sterilisation is commonly used to preserve food products.At the laboratory scale, huge steel veels with live stream at 105 kPa are commonly used for 20–30 minutes.This is a closed system known as an autoclave;therefore it is batch sterilisation.Wet steam is usually used for effective autoclaving.The high temperature and long duration may kill all living microorganisms, spores and viruses.