Mariprofundus ferrooxydans is a neutrophilic, chemolithotrophic, Gram-negative bacterium which can grow by oxidising ferrous to ferric iron.

[4] The bacterium was isolated from iron-rich microbial mats associated with hydrothermal vents at a submarine volcano, Kamaʻehuakanaloa Seamount (formerly Lōʻihi), near Hawaii, and has only 85.3% 16S similarity to its nearest cultivated species Methylophaga marina.

[2] Despite being validly published,[3] the etymology of the generic epithet is grammatically incorrect, being a concatenation of the Latin neutral mare -is (the sea) with the Latin masculine adjective profundus (deep) intended to mean a deep-sea organism (the neuter of profundus is profundum).

[3] The specific epithet is ferrum (Latin noun), iron and oxus (Greek adjective), acid or sour, and in combined words indicating oxygen.

[4] M. ferrooxydans is capable of fixing CO2 using RuBisCo genes encoded in its genome; it has multiple different RuBisCo genes which suggests that the organism has adapted to fix CO2 across a broader spectrum of concentrations of oxygen and carbon dioxide.

[4] This organism has never been observed to grow heterotrophically, yet its genome encodes for a sugar phosphotransferase system, typically used as a carbohydrate transporter, which is specific for fructose and mannose.