Diversity and Biotechnological Applications of Prokaryotic Enzymes

The global enzyme market was estimated at US $5 billion in 2009. Taking into consideration the compound annual growth rate (CAGR) of 6 % for the next 5 years, this market is expected to reach US $7 billion by 2015. Enzymes have been used in a wide range of applications in the fuel, pharmaceutical, brewing, food, animal feed, bioremediation, detergent, paper, and textile industries. The industrial sector is under continuous pressure to use more environmentally friendly processes and to find new methods to make products more competitive. Consequently, microbial enzymes are increasingly replacing conventional chemical catalysts in a range of industrial processes. Microbial enzymes present some advantages when compared to enzymes sourced from plants and animals which may be seasonal. There is a reliable supply of raw material to make microbial enzymes whenever necessary, and their production in bioreactors is easily controlled and predictable; excreted microbial enzymes are more robust in comparison to the intracellular animal and plant enzymes, and the microbial genetic diversity is a source of biocatalysts with a wide specificity range. This chapter is a review of the important prokaryotic enzyme families used in present-day biotechnology. A comprehensive survey on lipases, amylases, transglutaminases, cellulases, peroxidases, and peptidases, including keratinases, is presented. This chapter also focuses on the types of catalyzed reactions, the mechanisms of enzyme actions, and the main producing microorganisms, as well the contribution of molecular biology for enzyme production. 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.