exiguobacterium aurantiacum exiguobacterium aurantiacum exiguobacterium aurantiacum is a gram-positive, alkaliphilic, halotolerant and non-spore-forming bacterium from the genus of exiguobacterium which has been isolated from human blood. exiguobacterium aurantiacum scientific classification domain: bacteria phylum: bacillota class: bacilli order: bacillales family: bacillaceae genus: exiguobacterium species: e. aurantiacum binomial name exiguobacterium aurantiacumcollins et al. 1984