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Articles from Springer a leading global scientific publisher of scientific books and journals. - biotechnology @ Tue, 18 Sep 2018 at 07:30 AM
Design for Values in Agricultural Biotechnology - Handbook of Ethics, Values, and Technological Design @ 2021-01-01
Agricultural biotechnology dates from the last two decades of the twentieth century. It involves the creation of plants and animals with new useful traits by inserting one or more genes taken from other species. New legal possibilities for patenting transgenic organisms and isolated genes have been provided to promote the development of this new technology. The applications of biotechnology raise a whole range of value issues, like consumer and farmer autonomy, respect for intellectual property, environmental sustainability, food security, social justice, and economic growth. Hitherto the field has not yet witnessed any deliberate attempt at value-sensitive design or design for values. The reason is that under the influence of strong commercial motivations, applications have been developed first and foremost with simple agronomic aims in view, such as herbicide tolerance and insect resistance, traits which are based on single genes. The opportunities for value-sensitive design appear to be constrained by the special character of the biological domain. Many desirable traits like drought tolerance are genetically complex traits that cannot be built into organisms by the insertion of one or a few genes. Another problem is that nature tends to fight back, so that insects become immune to insect-resistant crops and weeds become invulnerable to herbicides. This leads to the phenomenon of perishable knowledge, which also calls the so-called patent bargain into question. The possibilities for value-sensitive design will likely increase with synthetic biology, a more advanced form of biotechnology that aims at making biology (more) “easy to engineer.” Practitioners of this new field are acutely aware of the need to proceed in a socially responsible way so as to ensure sufficient societal support. Yet synthetic biologists are currently also engaged in a fundamental debate on whether they will ultimately succeed in tackling biological complexity.
Enzymes are the key substances responsible for a variety of biotechnological processes involved in the production of useful bioproducts. Malt and microbial species (bacteria, fungi, etc.) are the main sources of endogenous hydrolyzing enzymes (EHEs). EHEs are primarily involved in the digestion of complex substrates into simpler units and the resulting formation of biological products. Based on origin and substrate specificity, EHEs are categorized into cell wall-, starch-, protein-, lipid-, nucleic acid-, polyphenol-, and thiol-hydrolyzing enzymes. The substrate specificities and reaction mechanisms of individual EHEs and groups of EHEs have been verified through isolated and purified enzymes. A number of methods have been reported for high-yield, economically feasible isolation of enzymes. The endogenous enzymes contained in microbial cells are separated from cells, cellular fragments, and organelles through several cell lysis and separation methods. Analysis of the mechanism of action has revealed that most enzymes systematically undergo biological processes through a cascade of enzyme-specific reactions. The applications of these EHEs are involved in almost every aspect of human and animal life and are important in food, animal feed, textile, paper and pulp, fuel (energy), pharmaceutical, and chemical industries. In this chapter, we describe the origins, classes, isolation techniques, mechanisms, and applications of various EHEs with examples from updated literature.
Cellulose from Lignocellulosic Waste - Polysaccharides @ 2021-01-01
Bioconversion of renewable lignocellulosic biomass to biofuel and value-added products is globally gaining significant importance. Lignocellulosic wastes are the most promising feedstock considering its great availability and low cost. Biomass conversion process involves mainly two steps: hydrolysis of cellulose in the lignocellulosic biomass to produce reducing sugars and fermentation of the sugars to ethanol and other bioproducts. However, sugars necessary for fermentation are trapped inside the recalcitrant structure of the lignocellulose. Hence, pretreatment of lignocellulosic wastes is always necessary to alter and/or remove the surrounding matrix of lignin and hemicellulose in order to improve the hydrolysis of cellulose. These pretreatments cause physical and/or chemical changes in the plant biomass in order to achieve this result. Each pretreatment has a specific effect on the cellulose, hemicellulose, and lignin fraction. Thus, the pretreatment methods and conditions should be chosen according to the process configuration selected for the subsequent hydrolysis steps. In general, pretreatment methods can be classified into four categories, including physical, physicochemical, chemical, and biological pretreatment. This chapter addresses different pretreatment technologies envisaging enzymatic hydrolysis and microbial fermentation for cellulosic ethanol production and other bioproducts. It primarily covers the structure of lignocellulosic wastes; the characteristics of different pretreatment methods; enzymatic hydrolysis; fermentation and bioproducts; and future research challenges and trends.
Cyclodextrins - Polysaccharides @ 2021-01-01
Cyclodextrins - Polysaccharides @ 2021-01-01
Cosmetics are complex multiphase systems that include different components with distinct functions on the final product. Bacterial polysaccharides are biocompatible, biodegradable, and usually nontoxic natural biopolymers that possess physicochemical properties suitable for use as cosmetic ingredients. Some of them, namely, hyaluronic acid (HA), bacterial cellulose (BC), and levan, have biological properties (e.g., skin regeneration and protection) and are used as active agents in cosmetic formulations. Other bacterial polysaccharides, such as xanthan gum and gellan gum, are mostly used as viscosity controllers and psychosensorial agents and are applied in cosmetic vehicles (e.g., emulsions, gels, and suspensions). The nontoxic nature of these bacterial polysaccharides has been thoroughly assessed by innumerous studies and their safety as cosmetic ingredients has been established.
Dietary Fiber and Prebiotics - Polysaccharides @ 2021-01-01
Dietary fiber and prebiotics exert a great impact on health-promoting food for mankind. Under this aspect a general overview is given about the bioavailability of carbohydrates and their influence on dietary fiber intake and about the developing of the prebiotic concept and specific functional foods. Moreover, the occurrence and chemical composition of native dietary fiber such as resistant starch, pectin, hemicelluloses, ß-glucan, and fructan in context to their properties – in particular the prebiotic potential for human health – will be discussed. Important industrially produced bioactive carbohydrates from plant and seaweed sources with high prebiotic efficacy and increasing economic interest such as fructan – particularly inulin and fructooligosaccharides (FOS), heteropolysaccharides, xylooligosaccharides (XOS), and isomaltooligosaccharides (IMO) – will be presented. Additionally enzymatic processing of prebiotic-active oligosaccharides such as FOS, galactooligosaccharides (GOS), or nondigestible disaccharides such as isomaltulose and trehalulose derived from sucrose and lactose will be demonstrated and discussed.
Since their first discovery in 1790–1825, pectins are still fascinating plant and food scientists who continue to carry out numerous structural as well as functional studies on them. This great interest of scientists for pectins is accounted for by their large spectrum of (bio)functionalities, starting from their natural location in plant cell walls as bioactive components for cell growth, defense, and protection via diverse manufactured food and nonfood products as techno-functional (gelling, emulsifying, film-forming, etc.) agents to terminate in human welfare as health-benefit (prebiotic, anticomplementary, antioxidant, anticancer, etc.) agents. The extraordinary functional versatility of pectins is thought to be intimately related to fine structure. Unfortunately, structurally, pectins are extremely diversified that establishment of structure-function relationship appeared so far a difficult task to go through. On the other hand, the extended structural variability of pectins presages for the finding of new functions hitherto unknown. Nevertheless, for some structurally well-known pectic cobiopolymers such as homogalacturonan, solid evidence for structure-related functions, especially gelling properties, has been provided, including new insights very recently.After a brief introduction on the “pectin structural repertoire,” the main sources of industrial pectins will be exposed, followed by a succinct structural description of the different pectic block cobiopolymers, commonly referred to as “pectic polysaccharides.” Finally, some remarkable structure-related functions, namely, gelling, emulsifying/emulsion-stabilizing, and antitumor properties of pectins will be revisited in the light of the latest work.
The interest in bio-based polymers, especially extracellular polysaccharides (EPSs), has increased considerably in recent years due to their useful physicochemical and rheological properties and diverse functionality. Microbial polysaccharides have many commercial applications in different industrial sectors like chemical, food, petroleum, health, and bionanotechnology. Although microbial EPS production processes are regarded as environmentally friendly and in full compliance with the biorefinery concept, EPSs constitute only a minor fraction of the current polymer market due to their cost-intensive production and recovery. For that reason, much effort has been spent to the development of cost-effective production processes by using cheaper fermentation substrates such as low-cost biomass resources. These resources are generally either in liquid form like syrups, molasses, juices, cheese whey, and olive mill wastewater or solid-like lignocellulosic biomass and pomaces. In this chapter, after a brief description of microbial polysaccharides, submerged and solid-state fermentation processes utilizing cheap biomass resources are discussed with a special focus on the microbial production of EPSs with high market value.
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