Bifidobacterium aesculapii sp. nov., from the faeces of the baby common marmoset (Callithrix jacchus)

Gram-positive-staining, microaerophilic, non-spore-forming, fructose-6-phosphate phosphoketolase positive bacterial strains with a peculiar morphology were isolated from faecal samples of baby common marmoset (Callithrix jacchus). Cells of these strains showed a morphology never found in bifidobacterial species, which resembled a coiled snake, always coiled or ring shaped or forming a "Y" shape. MRM 3/1 and MRM 4/2 were chosen as representative strains and further characterized. The bacteria utilized a wide range of carbohydrates and produced urease. Glucose was fermented to acetate and lactate. The strain MRM 3/1 showed a peptidoglycan type unique among members of the genus Bifidobacterium . The DNA base composition was 64.7mol% G+C. Almost complete 16S rRNA, hsp60, clpC and rpoB gene sequences were obtained and phylogenetic relationships were determined. Comparative analysis of 16S rRNA gene sequences showed that strains MRM 3/1 and MRM 4/2 had the highest similarities to Bifidobacterium scardovii (DSM 13734T) (94.6%) and Bifidobacterium stellenboschense (DSMZ 23968T) (94.5%). Analysis of hsp60 showed that both strains were closely related to B. stellenboschense (97.5%), however, despite this high degree of similarity, our isolates could be distinguished from B. stellenboschense DSMZ 23968T also by low levels of DNA-DNA relatedness (30.4%). Therefore, strains MRM 3/1 and MRM 4/2 were located in an actinobacterial cluster and were more closely related to the genus Bifidobacterium than to other genera in Bifidobacteriaceae. On the basis of these results strains MRM 3/1T and MRM 4/2 represent a novel species within the genus Bifidobacterium, for which the name Bifidobacterium aesculapii sp. nov. is proposed; the type strain is MRM 3/1T (=DSM 26737T;= JCM 18761T).