General Information: Elusimicrobium minutum (strain Pei191) is a mesophilic, obligately anaerobic free-living ultramicrobacterium with a Gram-negative cell envelope isolated from the intestinal cluster from the hindgut of a humivorous scarab beetle larva. This species is an endosymbiont of flagellated protists which occur almost exclusively in the hindgut of termites and wood-feeding cockroaches.