''Halanaerobium fermentans'' is a

Gram-negative Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall ...

and strictly anaerobic bacterium from the genus of ''

Halanaerobium ''Halanaerobium'' is a Gram-negative, non-endospore-forming, rod-shaped, and strictly anaerobic genus of bacteria from the family Halanaerobiaceae. Phylogeny The currently accepted taxonomy is based on the List of Prokaryotic names with Standi ...

'' which has been isolated from puffer fish ovaries.

References

Clostridia Bacteria described in 2000 {{Firmicutes-stub