This book comprises a total of 14 chapters contributed by experts from different countries worldwide. It is a comprehensive collection of articles to illustrate an overview of microbial catalysts that include enzymes widely contribute to many fields infood and industrial products. Microorganisms have served and continue to serve as one of the largest and most useful sources of many enzymes used in foods and the food industry. Microbial catalysts are environmentally friendly and consume lower energy. A particular aim of this book is focused on applied and industrial microbiology, agricultural microbiology, and food microbiology. All sections discuss microbial catalysts viz., enzymes with respect to their function and its benefit to human kind especially, and to biotechnology as a subject of which enzymology is an integral part. The book also deals with structure and function of some microbial enzymes. Microbial catalysts are generally preferred than plant and animal as sources of industrial enzymes because their production cost is low. In addition, enzymes are more predictable and controllable, and more so because of the easy availability of raw materials with constant composition for their cultivation.