This book is an attempts to provide an overview of the various components of industrial enzyme production process and purification of enzymes, followed by enzyme applications. Commercial enzyme production has grown from the traditional natural microbial sources utilization in either submerged or solid state fermentation to a vast range of products in response to ever expanding markets and increasing demand for novel biocatalysts. Microorganisms constitute the major source of genetically modified organisms for recombinant enzymes production, but several enzymes are also obtained from animal and plant expression systems. Traditional enzyme production relied on the natural hosts as raw materials, for screening of enzyme producing microorganisms, most commonly from soil. After isolation of such a microbial source, the enzyme is produced in bulk in fermentation process, followed by the downstream processing of the enzyme to get high concentration of pure enzyme. The desired level of purity is dependent upon the ultimate applicability and use of the enzyme. The applicability of enzymes in solution and in immobilized conditions is discussed in the book.