Enzymes are necessary for nearly all of life's chemical reactions. With the advance of biotechnology, increasing numbers of enzymes are identified and over-produced prior to application in various industries that encompass medicine, agro-industry, commodity products sectors, and biofuel biotechnologies. Many enzymes currently are derived from recombinant microorganisms. Enzyme manufacturers take advantage of new genetic techniques to develop and manufacture enzymes with improved properties. Such enzymes often originate from microorganisms that cannot be readily cultured under laboratory or industrial conditions. By judicious selection of host microorganisms, recombinant production strains can be constructed to allow efficient production of enzymes that are substantially free of undesirable enzymes or other microbial metabolites. The developments in molecular genetics and cell biology in the last four decades have reshaped enzyme production. This book provides comprehensive material on applications of important microbes and their gene functions in enzyme technology for audiences across many disciplines.