Extremophiles, a Unique Resource of Biocatalysts for Industrial Biotechnology

Abstract

This chapter focuses on extremophilic archaea and extremophilic bacteria and their relevance for industrial biotechnology. The majority of extremophiles identified to date belong to the archaeal domain (nearly 300 species), which consists of four kingdoms: Crenarchaeota, Euryarchaeota, Korarchaeota, and Nanoarchaeota. Other hemicellulases (glucoronidase, β-mannanase, β-mannosidase, galactosidase, acetyl xylan esterase, feruloyl esterase and α-arabinofuranosidase), isolated from extremophiles, are efficient enzymes for the complete saccharification of plant cell wall. In the field of industrial biotechnology, esterases too are gaining increasing attention because of their application in organic biosynthesis. The use of high pressure leads to better flavor and color preservation. On the other hand, a number of limitations did not allow so far the broad application of extremophiles. These limitations include difficulties associated with large-scale cultivation of extremophiles, non efficient systems for the overexpression of archaeal genes and unknown factors that confer enzyme stability under extremes of temperature, pH, and pressure. The growing demand for more robust biocatalysts has shifted the trend toward improving the properties of existing proteins for established industrial processes and producing new enzymes tailor-made for entirely new areas of application. The new technologies such as genomics, metanogenomics, gene shuffling, and mutagenesis provide valuable tools for improving or adapting enzyme properties to the desired requirements. Thus, the modern methods of genetic engineering combined with an increasing knowledge of structure and function and process engineering will allow further adaptation of biocatalysts to industrial needs, the exploration of novel applications and protection of the environment.