The genus Clostridium consists of over 295 species of gram-positive, rod-shaped bacteria. These are mostly anaerobes and present ubiquitously in the environment due to their ability to form heat, radiation and chemical resistant spores. In this book, the authors present current research in the study of the biotechnology, medicinal applications and implications of clostridia. Topics discussed include the biodegradation of organic pollutants, reduction of metals and energy generation involving Clostridium sp.; the utilisation of clostridium in industrial, biotechnological and medical endeavours; the clinical aspects of clostridium difficile associated with diarrhoea and the potential use of megasphaera elsdenii as a hydrogen producer.