Thermosyntropha tengcongensis sp nov., a thermophilic bacterium that degrades long-chain fatty acids syntrophically

A novel anaerobic, thermophilic, syntrophic, fatty-acid-oxidizing bacterium, strain L-60(T), was isolated from a Chinese hot spring. Cells of the strain were non-motile, non-spore-forming, slightly curved rods. Growth occurred between 55 and 70 degrees C (optimum about 60 degrees C) and at pH 7.0-9.3 (optimum about pH 8.2). Crotonate was the only tested carbon source that supported the growth of the strain in pure culture. In co-culture with the thermophilic, hydrogenotrophic Methanothermobacter thermautotrophicus DSM 1053(T), the isolate could oxidize saturated straight-chain fatty acids with 4-18 carbon atoms, and also unsaturated fatty acids such as oleate, syntrophically. The strain was unable to utilize sulfate, sulfite, thiosulfate, nitrate, fumarate or Fe(III) as electron acceptors. The major cellular fatty acids were C-14:0 (35.0%), C-16:0 (20.3%) and iso-C-17:1 l/anteiso-C-17:1 B (30.9 %). The genomic DNA G + C content was 40.3 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the strain was affiliated to the family Syntrophomonadaceae and was most closely related to Thermosyntropha lipolytica DSM 11003(T) (96.7% similarity). On the basis of phylogenetic and phenotypic evidence, it is proposed that strain L-60(T) represents a novel species, for which the name Thermosyntropha tengcongensis sp. nov. is proposed. The type strain is L-60(T) (=CGMCC 1.5161(T) = JCM 17260(T)).