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Chapter 22 : Biotechnology
Category: Microbial Genetics and Molecular Biology; Environmental Microbiology
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The biotechnology of the Archaea has been reviewed in recent articles. This chapter covers topics that include enzymes and molecules from archaea and the use of archaeal whole cells. It updates the current state of biotechnology of the Archaea, paying special attention to distinguish between extant and potential applications, to provide a realistic overview of the impact of these organisms on biotechnology. Among hydrolases, proteases, esterases/lipases, and glycoside hydrolases are important in industry. Glycosidases synthesize oligosaccharides in reactions of reverse hydrolysis or transglycosylation in which an alcohol or another sugar acts as acceptor instead of water. Microbial exopolysaccharides (EPS) are used as stabilizers, thickeners, and emulsifiers in several industries, and the major commercial exopolysaccharides derives from the bacterium Xanthomonas campestris. Compatible solutes from archaea have biotechnological roles as cryoprotectants and preservatives. Hydrogen gas is an attractive alternative to fossil fuel as it is a clean, nonpolluting source of energy. However, conventional production is based, at present, on the steam reforming of natural gas and petroleum, and microbial production of H2 is gaining increasing interest. Many studies on the microbial production of H2 have focused on the bacterial genera, Clostridium and Enterobacter. Extremophilic archaea have been considered an interesting source of molecules for novel biotechnological applications. Their stability and activity to extreme conditions make them useful alternatives to labile mesophilic counterparts.
Reaction mechanism of β-glycosidases. Hydrolysis occurs if “X” is a hydrogen (H) atom, or transglycosylation occurs if “X” is a different “R” group.
Reaction mechanism of hyperthermophilic glycosynthases. (A) Scheme of the glycosynthase mechanism: the transferred sugar is shown in bold. (B) Scheme of the processive glycosynthetic reaction: the transferred sugar in a chair conformation is shown with closed symbols; the aryl leaving group is shown as a hexagon.
The intein self-catalytic protein-splicing mechanism is shown.
Applications of extremozymes