Syntrophomonas curvata sp nov., an anaerobe that degrades fatty acids in co-culture with methanogens

A strict anaerobe (strain GB8- 1(T)) that degraded straight-chain fatty acids with C-4-C-18 in syntrophic association with methanogens was isolated from an up-flow anaerobic sludge blanket reactor treating beer wastewater. Strain GB8-1(T) degraded 1 mol butyrate into about 2 mol acetate and 1 mol (presumably) H-2 in co-culture with a methanogen. Neither branched-chain fatty acids nor benzoate could be degraded. Strain GB8- 1 T could grow on crotonate in pure culture and converted 1 mol crotonate to 0.5 mol butyrate and 1 mol acetate. Generation time was about 11 h when grown on crotonate at 37 degreesC. Fumarate, sulfate, thiosulfate, sulfur and nitrate could not serve as electron acceptors for strain GB8- 1 T to degrade butyrate. Cells of strain GB8-1(T) were curved rods with Gram-negative cell walls; no spores were observed. The DNA G+C content was 46.6 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain G138-1(T) was related most closely to the fatty acid-oxidizing, syntrophic bacterium Syntrophomonas sapovorans DSM 344 1(T); however, the relationship was not very close (95.4% sequence similarity). Some phenotypic features also differentiated strain G138-1(T) from Syntrophomonas sapovorans DSM 3441(T). Therefore, a novel species, Syntrophomonas curvata sp. nov., is proposed. The type strain is GB8-1(T) (=CGMCC 1.5010(T) = DSM 15682(T)).