There is a growing awareness that horizontal gene transfer (HGT) is a highly significant phenomenon among single-celled organisms. The evolution of bacteria and archaea most often results from the acquisition of new genes through horizontal transfer rather than by modification of vertically inherited genes. Horizontal or lateral gene transfer is a major factor in the spread of bacterial antibiotic resistance and other adaptive traits of microorganisms and is particularly significant in microbial communities. HGT may also play a substantial role in the emergence of novel infections and opportunistic pathogens. In this book, expert authors from around the world have contributed novel work and comprehensive, up-to-date reviews on the most topical aspects of HGT in microorganisms. Topics include: gene survival in emergent genomes * evolution of prokaryotic pangenomes * horizontal transfer of host-adaptability systems * barriers to horizontal gene transfer * evolution of horizontally transferred genes * lateral gene transfer in natural ecosystems * maintenance of plasmids among bacteria * mobile genetic elements in metagenomes * the evolution of antibiotic resistance genes. Aimed primarily at research scientists, graduate students, and other experts, this book will be a major resource for anyone interested in HGT, microbial evolution, or antibiotic resistance in bacteria. Horizontal Gene Transfer in Microorganisms is recommended for all microbiology laboratories.