- Like all living organisms, bacteria must communicate with the world around them. As they typically live as single cells, the communication with their environment must occur at the cell membrane, both in moving molecules in and out and in transmitting information about their surroundings to response elements within the cell. This volume is devoted primarily to methods used to study either the behavior of bacteria in response to their environment or methods used to study events that involve signaling pathways that are initiated by events at the cell membrane. The topics are arranged according to the scale of the events described: (1) Methods for studying bacterial chemotaxis at the population and whole-cell levels; (2) In vivo analysis of receptor function; (3) Cryo-EM methods for studying chemoreceptor structure; (4) Monitoring the intracellular movement of chemosensory proteins; (5) High-throughput methods for screening novel chemoeffectors; (6) Creating chemical tools for studying chemosensory signal transduction; (7) Computerized analysis of chemotaxis. Every effort has been made to get the most experienced and proficient practitioners of each of the methods described, and the editor is indebted to all who agreed to participate.