[¦meth·ə·nō‚män·ə′dās·ē‚ē] (microbiology) Formerly a family of bacteria in the suborder Pseudomonadineae; members identified as gram-negative rods are able to use carbon monoxide (Carboxydomonas), methane (Methanomonas), and hydrogen (Hydrogenomonas) as their sole source of energy for growth.