Affiliation:
1. College of Life Sciences, Northeast Agricultural University, Harbin 150030, PR China
Abstract
In 2018, Nouioui et al. transferred
Bifidobacterium gallinarum
and
Bifidobacterium saeculare
to
Bifidobacterium pullorum
as
B. pullorum
subsp.
gallinarum
and
B. pullorum
subsp.
saeculare
on the basis of digital DNA–DNA hybridization (dDDH) values. These two new subspecies were validated in the same year. However, we found that the genome (GenBank/ENA/DDBJ accession number JGZJ01000000) of
B. pullorum
used by Nouioui et al. in the dDDH analysis cannot represent
B. pullorum
. So, the taxonomic relationship between
B. gallinarum
,
B. saeculare
and
B. pullorum
should be re-examined.
B. pullorum
DSM 20433T had 88.7–89.0 % average nucleotide identity (ANI) values and 37.5–38.0 % dDDH values to the type strains of
B. gallinarum
and
B. saeculare
, respectively, less than the threshold for species demarcation, confirming that
B. pullorum
represents a different species from
B. gallinarum
and
B. saeculare
. The ANI values and dDDH values between the type strains of
B. gallinarum
and
B. saeculare
were 96.7–96.9 % and 73.0–73.3 %, respectively, greater than the threshold for species demarcation, confirming that they represent the same species. Relatively low dDDH values (less than the 79–80 % threshold for subspecies demarcation) between the type strains of
B. gallinarum
and
B. saeculare
indicated that
B. saeculare
can be considered as a subspecies of
B. gallinarum
. On the basis of the results presented here, (i)
B. gallinarum
and
B. saeculare
should not be transferred to
B. pullorum
; (ii) we propose
B. saeculare
Biavati et al. 1992 as a later heterotypic synonym of
B. gallinarum
Watabe et al. 1983 and as a new subspecies of
B. gallinarum
, for which the name
B. gallinarum
subsp. saeculare subsp. nov. is proposed.
Funder
National Natural Science Foundation of China
Subject
General Medicine,Ecology, Evolution, Behavior and Systematics,Microbiology