Caproiciproducens galactitolivorans gen. Nov., sp. nov., a bacterium capable of producing caproic acid from galactitol, isolated from a wastewater treatment plant

A strictly anaerobic, Gram-stain-positive, non-spore-forming, rod-shaped bacterial strain, designated BS-1^T, was isolated from an anaerobic digestion reactor during a study of bacteria utilizing galactitol as the carbon source. Its cells were 0.3–0.5 μm × 2–4 μm, and they grew at 35–45 ºC and at pH 6.0–8.0 Strain BS-1^T produced H₂, CO₂, ethanol, acetic acid, butyric acid and caproic acid as metabolic end products of anaerobic fermentation. Phylogenetic analysis, based on the 16S rRNA gene sequence, showed that strain BS-1^T represented a novel bacterial genus within the family Ruminococcaceae, Clostridium Cluster IV. The type strains that were most closely related to strain BS-1T were Clostridium sporosphaeroides KCTC 5598^T (94.5 %), Clostridium leptum KCTC 5155^T (94.3 %), Ruminococcus bromii ATCC 27255T (92.1 %) and Ethanoligenens harbinense YUAN-3^T (91.9 %). Strain BS-1^T had 17.6 % and 20.9 % DNA–DNA relatedness values with C. sporosphaeroides DSM 1294T and C. leptum DSM 753T, respectively. The major components of the cellular fatty acids were C_{16 : 0} dimethyl aldehyde (DMA) (22.1 %), C_{16 : 0} aldehyde (14.1 %) and summed feature 11 (iso-C_{17 : 0} 3-OH and/or C_{18 : 2} DMA; 10.0 %). The genomic DNA G+C content was 50.0 mol%. Phenotypic and phylogenetic characteristics allowed strain BS-1^T to be clearly distinguished from other taxa of the genus Clostridium Cluster IV. On the basis of these data, the isolate is considered to represent a novel genus and novel species within Clostridium Cluster IV, for which the name Caproiciproducens galactitolivorans gen. nov., sp. nov. is proposed. The type species is BS-1^T (=JCM 30532^T and KCCM 43048^T).