Identifying and characterizing Yarrowia keelungensis sp. nov., an oil-degrading yeast isolated from the sea surface microlayer.

Ascomycetous yeast strain SM-22 was isolated from the sea-surface microlayer near the Keelung City off the northern coast of Taiwan. This strain showed a cell surface hydrophobicity higher than 90 %, moderate UV A/B resistance, and it degraded 68 % of the total petroleum hydrocarbon content of an artificial seawater medium containing 1 % (v v(-1)) diesel oil within 15 days at 25 °C. The closest phylogenetic relative of this strain is Candida oslonensis CBS 10146(T), but it differs from strain SM-22 by a 3.7 % divergence (including 18 nucleotide substitutions and 2 gaps) in the D1/D2 domain sequence of the large subunit rRNA gene. This difference clearly suggests that the strain SM-22 represents a distinct species. Strain SM-22 does not produce ascospores on common sporulation media and it can therefore be considered an anamorph of the genus Yarrowia. Thus, the name Yarrowia keelungensis sp. nov. (type strain SM-22(T) = BCRC 23110(T) = JCM 14894(T) = CBS 11062(T)) is proposed as a novel species of genus Yarrowia.