This chapter brings an introduction to microbial enzymes as well as a description of the main groups of microorganisms used in the food industry. The advantages of microbial enzymes over animal and vegetal enzymes are described as well as the importance of the more friendly biotechnology processes. The most important enzymes used in the food industry, such as amylases, lipases, cellulases, peptidases, keratinases, transglutaminases, phytases, pectinases, lactases, glucose oxidase, glucose invertases and invertases, are examined as well as their applications in animal feed and human nutrition.