clostridium grantii clostridium grantii clostridium grantii is a gram-positive, strictly anaerobic, rod-shaped and spore-forming bacterium from the genus clostridium which has been isolated from the gut of a mullet. clostridium grantii scientific classification domain: bacteria phylum: bacillota class: clostridia order: eubacteriales family: clostridiaceae genus: clostridium species: c. grantii binomial name clostridium grantiimountfort et al. 1996 type strain a-1, cip 105529, dsm 8605