Extremophile enzyme application

Many scientists hope to discover other proteins that are stable at extremes of temperature, salt concentration, or pH. Biocatalysis can be a useful tool in a number of different applications. Just as Taq polymerase revolutionized PCR, other extremophilic enzymes might also serve as useful catalysts in commercially important reactions. T. aquaticus was a focus of much of the early work. In 1973, Stellwagen reported the isolation of a thermostable enolase from T. aquaticus YT-1. It was remarkably thermostable compared to enolases isolated from either yeasts or rabbit muscle cells. Taq... 

There are many existing and potential industrial applications of extremophilic enzymes (see Table 2), which take advantage of their capacity to thrive in harsh conditions, relative to their mesophilic (ie, function under moderate conditions) counterparts. For example, the detergent industry makes extensive use of alkaline-stable proteases, accounting for approximately 30% of global enzyme production (27). Enzymes from extremophiles have been used for bioremediation heavy metals and radionuclides from wastewaters (28), as well as for biodegrading hydrocarbons in polar soils (29). It is likely that extremophilic enzymes will find wide use in applications that strategically use their intrinsic robustness as biocatalysts. 

F. Niehaus, C. Bertoldo, M. Kahler, and G. Anthranikian, Extremophiles as a source of novel enzymes for industrial application, Appl. Microbiol. Biotechnol. 

A quite interesting area with considerable application potential opens up with enzymes obtained from extremophiles [89]. First reports on properties and functions described a novel a-glucosidase from the acidophilic archaeon Ferroplasma acidiphilium strain Y [90] and two /3-glucosidases from a thermo-tolerant yeast Pichia etchellsii [91]. 

A number of smaller enzyme-producing companies focus on thermophilic micro-organisms (and other extremophiles) to identify and produce new types of thermostable enzymes Unitika, Pacific Enzymes, Genis, Diversa (formerly Recombinant BioCatalysis), and others. One extremozyme that has already found commercial application is the heat-stable DNA polymerase from Thermus aquaticus (Taq-polymerase) that gave rise to the polymerase chain reaction (PCR). Using PCR, nucleic acids or segments of DNA can by amplified in vitro without having to replace the enzyme after each amplification cycle when the DNA template is denatured by heat. A number of new hyperthermophilic enzymes with temperature optima between 75 and 118°C have been described in the past few years [81], such as... 

Extremophiles are a source of evolution-hardened enzymes and principles, such as thermostable enzymes (Taq polymerase for PCR) and cold-adapted enzymes with applications in the detergent and food industries, fine chemicals production, bioremediation as well as broader applicable mechanisms for then- high catalytic efficiency based on stractural X-ray studies. 

The class I FruA isolated from rabbit muscle ( RAMA ) is the aldolase used for preparative synthesis in the videst sense, because of its commercial availability and useful specific activity of 20 U mg. Its operating stability in solution is limiting, but recently more robust homologous enzymes have been cloned, e.g. from Staphylococcus camosus [152] or from the extremophilic Thcrmus aquaticus [153], vhich promise to be unusually stable in synthetic applications [154]. Attempts at catalyst immobilization have been performed vith rabbit muscle FruA, vhich has been covalently attached to microcarrier beads [58], cross-linked in enzyme crystals (CLEG) [59], or enclosed in a dialysis membrane [73]. It vas recently sho vn that... 

Despite the promising performance of newly studied enzymes in the laboratory, their application in the industrial milieu might fail due to their lack of robustness. However, as anaerobic, extremophilic, and marine bacteria might be a source of enzymes with superior chances of success in biotechnological processes, a great deal of laboratory effort has been concentrated on their production and characterization. Furthermore, the design of novel enzymes as well as molecular approaches such as enzyme evolution and metagenomic approaches can be used to identify and develop novel biocatalysts from uncultured bacteria—a treasure of unknown proteins. 

Nghiem NP, Taylor F, Johnston DB, Shelly JK, Hicks KB (2011) Scale-up of ethanol production from winter barley by the EDGE (enhanced dry grind enzymatic) process in fermentors up to 300 1. Appl Biochem Biotechnol 165(3-4) 870-882. doi 10.1007/sl2010-011-9304-1 Nichaus F, Bertoldo C, Kiihler M, Antranikian G (1999) Extremophiles as a source of novel enzymes for industrial application. Appl Microbiol Biotechnol 89 1267-1273... 

Johnston W, Cooney MJ, Liaw BY, Sapra R, Adams MWW. Design and characterization of redox enzyme electrodes new perspectives on established techniques with application to an extremophilic hydrogenase. Enzyme Microb Technol 2005 36 540-549. 

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