Abstract:
The 16S rRNA gene sequence analysis of Bifidobacterium species
reveals high interspecies sequence similarity in the range
of 87.7–99.5%. This study illustrated the extent of superiority of
a multigenic approach, involving protein-coding genes, in
comparison to the 16S rRNA gene, to precisely delineate presumptive
Bifidobacterium isolates obtained from probiotic milk
beverages, culture collections and pharmaceutical probiotic
preparations. Oligonucleotide pairs PurF-rev/PurF-uni; RpoCuni/
RpoC-rev; DnaB-uni/DnaB-rev; DnaG-uni/DnaG-rev; and
ClpC-uni/ClpC-rev amplified housekeeping genes while 27F/
1492R amplified the 16S rRNA gene of the presumptive bifidobacteria
in a polymerase chain reaction. Sequences of 16S
rRNA gene and some protein-coding genes effectively identified
the isolates. Phylogenetic analysis together with concatenation
showed that clpC, purF and dnaG genes had over 8-fold
better discriminatory power than the 16S rRNA gene in discriminating
between Bifidobacterium isolates. However, phylogenetic
analysis involving dnaB and rpoC gene sequences or
their concatenated trees showed discrepancies in clustering
isolates with designated type strains.
