eubacterium nodatum eubacterium nodatum eubacterium nodatum is a gram positive member of the oral flora of some patients with chronic periodontitis. it has been recently added to the red complex bacteria, that are most associated with disease. eubacterium nodatum scientific classification domain: bacteria phylum: bacillota class: clostridia order: clostridiale family: eubacteriaceae genus: eubacterium species: e. nodatum binomial name eubacterium nodatumholdeman et al. 1980