The field of industrial microbiology has been undergoing rapid change in recent years. First, what has been described as the 'cook book' approach has been largely abandoned for the rational manipulation of microorganisms on account of our increased knowledge of their physiology. Second, powerful new tools and technologies especially genetic engineering, genomics, proteomics, bioinformatics and such like new areas promise exciting horizons for man's continued exploitation of microorganisms. Third, new approaches have become available for the utilization of some traditional microbial products such as immobilized enzymes and cells, site-directed mutation and metabolic engineering. Simultaneously, microbiology has addressed itself to some current problems such as the fight against cancer by the production of anti-tumor antibiotics; it has changed the traditional practice in a number of areas: for example the deep sea has now joined the soil as the medium for the search for new bioactive chemicals such as antibiotics. Even the search for organisms producing new products has now been broadened to include unculturable organisms which are isolated mainly on genes isolated from the environment. Finally, greater consciousness of the effect of fossil fuels on the environment has increased the call in some quarters for the use of more environmentally friendly and renewable sources of energy, has led to a search for alternate fermentation substrates, exemplified in cellulose, and a return to fermentation production of ethanol and other bulk chemicals. Due to our increased knowledge and changed approach, even our definitions of familiar words, such as antibiotic and species seem to be changing. This book was written to reflect these changes within the context of current practice.