<em>Geobacillus</em> Bacteria: Potential Commercial Applications in Industry, Bioremediation, and Bioenergy Production

The genus Geobacillus is represented by obligately thermophilic bacteria able to grow in the temperature range of 35–75°C. They are modest bacteria isolated from various sources on routine media such as nutrient agar. Originally classified as representatives of Bacillus, the species of Geobacillus were established in 2001 as a new genus. However, sequence similarity between all species indicates that at least some species need to be reclassified at the genus level. In addition to 16S rRNA, housekeeping genes, 16S-23S rRNA gene internal transcribed spacer, and repetitive sequences can be used in classification and identification of thermophilic bacteria. The ability to survive and grow at high temperatures as well as utilization and synthesis of a wide range of compounds makes these bacteria and their products attractive for use in various spheres: food, paper, biotechnology industries, medicine, bioremediation, etc. A broad spectrum of applications arouses increased interest in the study of physiological and biochemical characteristics and triggers emergence of new usage areas for Geobacillus, such as bioenergy. The growing demand for energy leads to the development of alternative technologic options. Geobacillus species demonstrated the ability to generate or enhance productivity of important sources of bioenergy such as ethanol, isobutanol, 2,3-butanediol, biodiesel, and biogas