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

Abstract

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 mu m x 2-4 mu m, and they grew at 35-45 degrees C and at pH 6.0-8.0. Strain BS-1(T) produced H-2, 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-1(T) were Clostridium sporosphaeroides KCTC 5598(T) (94.5 %), Clostridium leptum KCTC 5155(T) (94.3 %), Ruminococcus bromii ATCC 27255(T) (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 1294(T) and C. leptum DSM 753(T), 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)).