1888 21 The Genus Geobacillus and Hydrocarbon Utilization

The members of the Gram-positive endospore-forming bacteria that made up the genus Bacillus have been gradually subdivided, during the last few years, into a number of new genera such as Alicyclobacillus, Aneuribacillus, Brevibacillus, Gracilibacillus, Paenibacillus, Salibacillus, Ureibacillus, and Virgibacillus. Nazina et al. in 2001 created the genus Geobacillus based around Bacillus (now Geobacillus) stearothermophilus DSM22 as the type strain. The description included two new species of hydrocarbon-oxidizing bacteria isolated from hightemperature oilfields, and the transfer of six members of genetic group 5 thermophilic species of Bacillus to the new genus. Other additions followed and, most of these species, shared the ability to grow at elevated temperatures and degrade hydrocarbons. The taxonomy of geobacilli, hydrocarbon degradation, molecular basis of thermophily, survival, and ecological roles in the environment and possible exploitation potential will be reviewed in this chapter.