Priestia

Priestia is a genus of mostly Gram-positive (P. flexa stains Gram-variable and P. koreensis stains Gram-negative), rod-shaped bacteria in the family Bacillaceae from the order Bacillales. The type species of this genus is Priestia megaterium.

Members of Priestia are previously species belonging to Bacillus, a genus that has been recognized as displaying extensive polyphyly within its members due to the vague criteria used to assign species to this clade. Multiple studies have been conducted using comparative phylogenetic analyses as a means to clarify the evolutionary relationships between Bacillus species, resulting in the transfer of species into numerous novel genera such as Alkalihalobacillus, Brevibacillus, Solibacillus, Alicyclobacillus, Virgibacillus and Evansella. In addition, the genus Bacillus has been restricted to only include species closely related to Bacillus subtilis and Bacillus cereus.

Priestia is named after the British microbiologist Fergus G. Priest (professor, Heriot-Watt University, Edinburgh; 1948–2019) for his many contributions to the systematics and uses of the members of the genus Bacillus.