Dialister hominis sp. nov., isolated from human faeces

An obligately anaerobic, Gram-stain-negative, rod or coccobacilli organism was isolated from a faecal sample of a healthy Japanese woman. In the 16S rRNA gene sequence analysis, strain 5BBH33(T) showed the highest 16S rRNA gene sequence similarity to Dialister succinatiphilus YIT 11850(T) (95.9%), Dialister propionicifaciens ADV 1053.03(T) (94.3 %), Dialister micraerophilus DSM 19965(T) (93.1%), Dialister invisus DSM 15470(T) (92.5%) and Dialister pneumosintes ATCC 33048(T) (91.4%). The hsp60 gene sequence analysis also revealed strain 5BBH33(T) had relatively low hsp60 gene sequence similarities (74.4-85.3%) to other Dialister species. Strain 5BBH33(T) showed 21.8-23.9% in silico DNA-DNA hybridization values with other Dialister species. In addition, the average nucleotide identity values between strain 5BBH33(T) and other Dialister species ranged from 68.7-74.2 %, indicating that this strain should be considered as new species based on whole-genome relatedness. Strain 5BBH33(T) was asaccharolytic and largely unreactive for commercial kit. However, its growth was enhanced by adding 1 % (w/v) succinate to the medium; strain 5BBH33(T) was able to decarboxylate succinate to propionate. The strain 5BBH33(T) genome contained the enzymes involved in succinate utilization. These results improve our understanding of succinate-utilizing bacteria. On the basis of the collected data, strain 5BBH33(T) represents a novel species in the genus Dialister, for which the name Dialister hominis sp. nov. is proposed. The type strain of D. hominis is 5BBH33(T) (=JCM 33369(T)=DSM 109768(T)).