Desulfothermus okinawensis sp. nov., a thermophilic and heterotrophic sulfate-reducing bacterium isolated from a deep-sea hydrothermal field

A novel thermophilic and heterotrophic sulfate-reducing bacterium, strain TFISO9(T), was isolated from a deep-sea hydrothermal field at the Yonaguni Knoll IV in the Southern Okinawa Trough. The cells were motile rods 2.5-5.0 microm in length and 0.6-0.9 microm in width. Strain TFISO9(T) was an obligate heterotroph and reduced sulfate. It grew between 35 and 60 degrees C (optimum 50 degrees C), at pH 5.4-7.9 (optimum pH 5.9-6.4) and with 1.5-4.5 % NaCl (optimum 2.5 %). The fatty acid composition was C(16 : 0) (61.5 %) and 12Me(16 : 0) (38.5 %). The DNA G+C content was 34.9 mol%. The 16S rRNA gene sequence analysis indicated that strain TFISO9(T) belonged to the genus Desulfothermus. Based on physiological and phylogenetic characteristics, strain TFISO9(T) represents a novel species for which the name Desulfothermus okinawensis sp. nov. is proposed. The type strain is TFISO9(T) (=JCM 13304(T)=DSM 17375(T)).