Dialister hominis sp. nov., isolated from human faeces

Abstract

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).

Keywords: Dialister; hsp60; human faeces; succinate-utilizing bacteria.