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''O. kitaharae'' is a lactic acid bacterium (LAB) that was isolated from composting distilled shochu residue produced in Japan. This species represents only the second member of the genus ''Oenococcus'' to be identified. ''O. kitaharae'' has the ability to ferment maltose, citrate and malate and the ability to synthesize specific amino acids such as L-arginine and L-histidine unlike some ''O. Oeni''. In addition to these metabolic differences, the ''O. kitaharae'' genome also encodes many proteins involved in defense against both bacteriophage (restriction-modification and [https://en.wikipedia.org/wiki/CRISPR CRISPR]) and other microorganisms (bacteriocins), and has had its genome populated by at least two conjugative [https://en.wikipedia.org/wiki/Transposable_element transposons], which is in contrast to currently available genome sequences of ''O. oeni'' which lack the vast majority of these defense proteins. It therefore appears that the genome of ''O. kitaharae'' has been shaped by its need to survive in a competitive growth environment that is vastly different from that encountered by ''O. oeni'', where environmental stresses provide the greatest challenge to growth and reproduction. <ref name="IdentificationofOK">[http://www.microbiologyresearch.org/docserver/fulltext/ijsem/56/10/2345.pdf?expires=1500421799&id=id&accname=guest&checksum=4FF9F1182BE36F4DF3395E34D812B03C. Identifcation of O. Kitaharae, Authors: Akihito Endo1, Sanae Okada1 10/1/2006 .]</ref>

One of the defining biochemical differences between ''O. kitaharae'' and ''O. oeni'' that was noted in its original isolation was the ability of ''O. kitaharae'' to produce acid from maltose. This trait is rare in ''O. oeni'', which is formally classified as maltose negative. By comparing available whole-genome annotations for ''O. oeni'' with ''O. kitaharae'', it was possible to identify several genes associated with sugar utilization that are deferentially present across the species. Of these, at least four genes which are present in ''O. kitaharae'', but absent in the ''O. oeni'' genomes, are predicted to be involved in the utilization of maltose, providing a direct genetic basis for this phenotype. In addition to genes predicted to be involved in the species-specific utilization of maltose, there are several [https://en.wikipedia.org/wiki/Open_reading_frame ORFs] predicted to be involved in the metabolism of trehalose, D-gluconate, D-ribose and fructose that are specifically present in ''O. kitaharae''. While the assimilation of these sugars is often carried out by specific strains of ''O. oeni'', this genotypic data agrees well with biochemical tests performed previously that indicated that ''O. kitaharae'' was able to utilize all of these various carbon sources. <ref name="link">[http://journals.plos.org/plosone/article/authors?id=10.1371/journal.pone.0029626 . Functional Divergence in the Genus Oenococcus as Predicted by Genome Sequencing of the Newly-Described Species, Oenococcus kitaharae, Authors Anthony R. Borneman, Jane M. McCarthy, Paul J. Chambers, Eveline J. Bartowsky 01/3/2012 .]</ref>