One of the most fascinating aspects of alkaliphiles is their ability to maintain pH homeostasis under extreme environmental conditions. This work provides a treatment of alkaliphilic microbiology, supported by molecular studies on the genetics of alkaliphilic Bacillus strain. Genomic analysis of Bacillus halodurans C-125 has been started and the genes responsible for alkaliphily are described. In addition to a basic background of alkaliphiles, including discussions of cell structures, physiology and molecular biology, Alkaliphiles presents an analysis of extracellular enzymes. Research on numerous enzymes including alkaline proteases, starch-degrading enzymes, cellulases, mannan-degrading enzymes, and many others is described in depth with relevant industrial applications.