Bacillus stratosphericus is a gram-positive, motile, rod-shaped bacteria that was isolated, cultured and characterized from atmospheric samples collected in 2001 from altitudes between 24-41 km in an exploratory collecting venture employing a balloon equipped with cryogenic tubes. Based on characteristics such as being endospore-forming, catalase-positive bacteria, and from phylogenetic analysis of 16S rRNA gene sequence, B. stratosphericus was identified as a novel strain of the genus Bacillus, collected at 41 km in altitude. Three other novel Bacillus strains were also identified from samples collected at different altitudes in this sampling trip, these are B. aerius, B. aerophilus and B. altitudinis. All four were found to be more resistant to UV radiation than their close ground-residing relatives, which is consistent with living at altitudes where UV radiation is more intense than on the ground.

Bacillus stratosphericus made headlines when it was discovered to be a powerful potential workhorse for microbial fuel cells (MFCs). In February 2012 a team of scientists from Newcastle University in the United Kingdom and Yangzhou University in China, working to develop MFCs as low-cost, portable, bacteria-powered batteries which take advantage of catalytic oxidation in anaerobic conditions to convert organic matter into electricity, published their results of “prospecting” for appropriate bacteria in the river Wear, in Sunderland, UK. Bacillus stratosphericus was collected and identified from a consortium of 75 different bacterial strains these scientists collected, and when isolated and tested, proved to be capable of high power generation. Although believed to live primarily in the stratosphere, atmospheric cycling is thought to bring B. stratosphericus (and other stratospheric bacteria) to earth, explaining its presence in the river Wear estuary. Culturing B. stratosphericus along with 25 other bacterial strains also selected for their potential to efficiently generate power allowed the research team to engineer a super biofilm, which nearly doubled the output of the microbial fuel cell they are developing. This strategy of selecting particularly productive bacterial strains may inspire assays of other extreme environments, such as the deep sea, to identify more species with high power-generating capabilities for use in MFCs.

(Gavaghan 2012; Newcastle University Press Office 2012; Shivaji et al. 2006; Wainwright 2012; Zhang et al. 2012)