Thermosipho geolei sp nov., a thermophilic bacterium isolated from a continental petroleum reservoir in Western Siberia

The novel isolate reduced elemental sulfur ana cystine. but not thiosulfate sulfate, to hydrogen sulfide, The G+C content of the genomic DNA was 30.0 mol%, As determined by 16S rDNA sequence analysis, this organism Three stri ctly anaerobic, thermophilic bacteria (SL31(T), SL30 and MLM39636) were iso lated from a deep continental oil reservoir in Western Siberia (Russia), Fo llowing the mid-exponential phase of growth, the non-motile rod-shaped orga nisms were surrounded by a sheath-like structure, As DNA-DNA hybridizations showed that these strains were highly related genomically, only strain SL3 1T was studied in detail, The temperature range for growth of strain SL31T was between 45 and 75 degreesC, with optimum growth at 70 degreesC, its opt imum ph and NaCl concentration for growth were pH 7.5 and 20-30 g l(-1), re spectively. The novel isolate reduced elemental sulfur and cystine, but not thiosulfate or belonged to the genus Thermosipho. DNA-DNA hybridization le vels between strain SL31T and type strains of the previously described spec ies of Thermosipho were less than 10%, On the basis of physiological and mo lecular properties, it is proposed that this organism should be placed in a new species, Thermosipho geolei sp, nov, The novel organism represents the first species of the genus Thermosipho that has been isolated from a petro leum reservoir, The type strain is SL31(T) (= DSM 13256(T) = JCM 10986(T)).