Listeria grayi is a species of bacteria. It is a Gram-positive, facultatively anaerobic, motile, non-spore-forming bacillus. It is non-hemolytic. The species was first proposed in 1966. It is named after M.L. Gray, an early researcher in L. monocytogenes[2] There are two subspecies of L. grayi: L. gray subs. grayi, and L. grayi subsp. murrayi.[3]
Listeria murrayi (named after a co-founder of L. monocytogenes) was originally a separate species of Listeria when proposed in 1971.[4] However, there was controversy over whether L. grayi and L. murrayi were the same species, or belonged in genus Listeria altogether. In 1974, researchers suggested that a new genus be created for the two species, called, Murraya,[5] although furthers studies by other researchers in 1987 proposed that the two species remain in Listeria.[6] In 1996, further studies showed that L. murrayi was a subspecies of L. grayi.[2]
^Larsen, H. E., & Seeliger, H. P. R. (1966). A mannitol fermenting Listeria: Listeria grayi sp. n. In Proceedings of the Third International Symposium on Listeriosis. Bilthoven.