nisaea (bacterium) nisaea (bacterium) nisaea is a genus in the phylum pseudomonadota (bacteria), which contains two species, namely n. denitrificans and n. nitritireducens, which were described in 2008. nisaea scientific classification domain: bacteria phylum: pseudomonadota class: alphaproteobacteria order: rhodospirillales family: thalassobaculaceae genus: nisaeaurios et al. 2008 type species nisaea denitrificans species nisaea denitrificans urios et al. 2008 nisaea nitritireducens urios et al. 2008 description like all proteobacteria the two species stain gram-negative.(,cf.) they were isolated from coastal, surface waters of the north-western mediterranean sea, specifically in february 2004 at the sola station located in the bay of banyuls-sur-mer (42 2.99 n 3 0.89 e) at a depth of 3 metres. the cells are motile pleomorphic rods that are 2.9 μm long and 0.9 μm wide. when grown on marine agar medium, they form cream colonies (i.e. no pigmentation). apart from standard genetic differences for species (98% 16s, 55% dna-dna), the two species differ in that nisaea denitrificans can fully denitrify whereas nisaea nitritireducens cannot only reduce nitrite. etymology