achromatium achromatium achromatium is a genus in the phylum pseudomonadota (bacteria). achromatium dividing achromatium, light micrograph of living cells. scientific classification domain: bacteria phylum: pseudomonadota class: gammaproteobacteria order: thiotrichales family: thiotrichaceae genus: achromatium type species a. oxaliferum etymology the name achromatium derives from:greek prefix a- (ἄ), not; greek noun chroma, color, paint; neo-latin neuter gender noun achromatium, that which is not colored. species the genus contains single species, namely a. oxaliferum ( schewiakoff 1893, species. (type species of the genus).; latin oxalis from the greek noun oxalis (ὀξαλίς), meaning sorrel, a toxic plant due to oxalic acid production; latin v. fero, to carry; neo-latin neuter gender adjective oxaliferum, oxalate-containing.