The genus Clostridium represents a heterogeneous group of anaerobic spore-forming bacteria, comprising prominent toxin-producing species, such as C. difficile, C. botulinum, C. tetani, and C. perfringens, in addition to well-known non-pathogens like solventogenic C. acetobutylicum. In the last decade, several clostridial genomes have been deciphered and post-genomic studies are currently underway. The advent of newly developed, genetic manipulation tools have permitted functional-based and systems biology analyses of several clostridial strains. Research in this area is at a very exciting stage. In this book, internationally recognized Clostridium experts critically review the most important aspects of clostridial research, providing the first coherent picture of the organism's molecular and cellular biology in this post-genomic era. The first major focus of the book is the genetics and molecular biology of the major clostridial toxins including: botulinum and tetanus neurotoxins, C. difficile large exotoxins, C. perfringens enterotoxin, pore-forming and binary bacterial toxins. Other topics include molecular epidemiology of C. botulinum and C. difficile, metabolic networks in C. acetobutylicum, development of genetic knock-out systems for clostridia, surface structures, anti tumor potential of clostridia, and antibiotic resistance determinants in C. difficile.