This book describes the design and the use of bioluminescent biosensors. It introduces beginners and experienced researchers starting in the microbiological biosensor domain to the practical aspects of building a luminescent microbial biosensor. It is also a source of information about other applications that use microbial cells. Each chapter focuses as far as possible on the technological conception of the presented biosensor with a clear demonstration of the issues in the design and how to reach the proof of concept. The book is divided into three practical sections facilitating the reader to easily access the information.