A taxonomic study was carried out on strain R8-12T, which was isolated from deep-sea water of the Indian Ocean during the screening of oil-degrading bacteria. The isolate was Gram-stain-negative, oxidase and catalase-positive. Growth was observed at salinities from 0.5 to 15 % (optimum 3 %), at pH from 6–10 (optimum 7–8) and at temperatures from 10 to 42 °C (optimum 28 °C). On the basis of 16S rRNA gene sequence similarity, strain R8-12T was shown to belong to the genus
Alcanivorax
and to be related to
Alcanivorax venustensis
DSM 13974T (97.2 %),
A. dieselolei
B-5T (95.0 %),
A. balearicus
MACL04T (94.6 %),
A. hongdengensis
A-11-3T (94.3 %),
A. jadensis
T9T (93.8 %),
A. borkumensis
SK2T (93.7 %) and
A. pacificus
W11-5T (93.7 %). The gyrB sequence similarities between R8-12T and other species of the genus
Alcanivorax
ranged from 77.9 % to 86.9 %. The major fatty acids were C16 : 0 (31.8 %), C18 : 1ω7c (20.3 %), C19 : 0ω8c cyclo (15.8 %) and summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7c) (8.9 %). The polar lipids were phosphatidylglycerol (PG), phosphatidylethanolamine (PE), two aminolipids (AL1–AL2) and two phospholipids (PL1–PL2). Three alkane hydroxylase (alkB) genes were identified in the genome. The G+C content of the chromosomal DNA was 66.1 mol%. DNA–DNA hybridization showed that strain R8-12T and
A. venustensis
DSM 13974T had a DNA–DNA relatedness of 63±3 %. According to its phenotypic features and fatty acid composition as well as the 16S rRNA and gyrB gene sequences, the novel strain represents a member of the genus
Alcanivorax
, but could be easily distinguished from all other known species of the genus
Alcanivorax
described to date. The name Alcanivorax marinus sp. nov. is proposed, with the type strain R8-12T ( = MCCC 1A00382T = LMG 24621T = CCTCC AB 208234T).