Exiguobacterium profundum sp. nov., a moderately thermophilic, lactic acid-producing bacterium isolated from a deep-sea hydrothermal vent

IRD, UMR180, IFR-BAIM, Universités de Provence et de la Méditerranée, ESIL case 925, 163 Avenue de Luminy, 13288 Marseille Cedex 9, France Correspondence Yannick Combet-Blanc yannick.combet-blanc{at}univmed.fr A facultatively anaerobic, halotolerant, moderately thermophilic and non-sporulating bacterium, designated strain 10C T , was isolated from deep-sea hydrothermal vent samples collected on the 13° N East Pacific Rise at a depth of approximately 2600 m. Cells of strain 10C T were Gram-positive, motile rods, and grew optimally at 45 °C (range 12–49 °C), pH 7.0 (range pH 5.5–9.5) and 0–2 % NaCl (range 0–11 %). (+)- L -Lactate was the main organic acid detected from carbohydrate fermentation with traces of formate, acetate and ethanol. Strain 10C T was catalase-positive, oxidase-negative and reduced nitrate to nitrite under anaerobic conditions. The DNA G+C content was 50.4 mol%. Its closest phylogenetic relatives were Exiguobacterium aestuarii TF-16 T and Exiguobacterium marinum TF-80 T (16S rRNA gene sequence similarity >99 %). However, strain 10C T differed genotypically from these two Exiguobacterium species as indicated by DNA–DNA relatedness data. Therefore, on the basis of phenotypic, genotypic and phylogenetic characteristics, strain 10C T is considered to represent a novel species of the genus Exiguobacterium , for which the name Exiguobacterium profundum sp. nov. is proposed. The type strain is 10C T (=CCUG 50949 T =DSM 17289 T ). The GenBank/EMBL/DDBJ accession number for the 16S rRNA gene sequence of strain 10C T is AY818050 .