RESUMO
A new group of anaerobic thermophilic bacteria was isolated from enrichment cultures obtained from deep sea sediments of Peru Margin collected during Leg 201 of the Ocean Drilling Program. A total of ten isolates were obtained from cores of 1-2 m below seafloor (mbsf) incubated at 60 degrees C: three isolates came from the sediment 426 m below sea level with a surface temperature of 9 degrees C (Site 1227), one from 252 m below sea level with a temperature of 12 degrees C (Site 1228), and six isolates under sulfate-reducing condition from the lower slope of the Peru Trench (Site 1230). Strain JW/IW-1228P from the Site 1228 and strain JW/YJL-1230-7/2 from the Site 1230 were chosen as representatives of the two identified clades. Based on the 16S rDNA sequence analysis, these isolates represent a novel group with Thermovenabulum and Caldanaerobacter as their closest relatives. The temperature range for growth was 52-76 degrees C with an optimum at around 68 degrees C for JW/IW-1228P and 43-76 degrees C with an optimum at around 64 degrees C for JW/YJL-1230-7/2. The pH(25C) range for growth was from 6.3 to 9.3 with an optimum at 7.5 for JW/IW-1228P and from 5 to 9.5 with an optimum at 7.9-8.4 for JW/YJL-1230-7/2. The salinity range for growth was from 0% to 6% (w/v) for JW/IW-1228P and from 0% to 4.5% (w/v) for JW/YJL-1230-7/2. The G+C [corrected] mol% of the genomic DNA was 46.3 +/- 0.7% (n = 4) for Thermosediminibacter oceani [corrected] JW/IW-1228PT [corrected] and 45.2 +/- 0.7 (n = 6) for Thermosediminibacter litoriperuensis [corrected] JW/YJL-1230-7/2T [corrected] DNA-DNA hybridization yielded 52% similarity between the two strains. According to 16S rRNA gene sequence analysis, the isolates are located within the family, Thermoanaerobacteriaceae. Based on their morphological and physiological properties and phylogenetic analysis, it is proposed that strain JW/IW-1228P(T) is placed into a novel taxa, Thermosediminibacter oceani, gen. nov., sp. nov. (DSM 16646(T)=ATCC BAA-1034(T)), and JW/YJL-1230-7/2(T) into Thermosediminibacter litoriperuensis sp. nov. (DSM 16647(T) =ATCC BAA-1035(T)).