This book examines several synthetic transcriptional regulatory circuits in bacteria. Chapter 1 presents a novel technique for shuffling short sequences of regulatory DNA to generate exponential libraries of functional sequences. Chapter 2 introduces a library of combinatorial promoters--genetic logic gates which integrate multiple environmental signals. Chapter 3 examines the role of genetic noise in transcriptional co-regulation using a three-color fluorescent reporter system. Chapter 4 showcases a synthetic circuit for the control of population density in a bacterial growth culture. These...