Genetic Study Reveals The Origins Of Cavity-causing Bacteria

Researchers have uncovered the complete genetic make-up of the
cavity-causing bacterium Bifidobacterium dentium Bd1, revealing the
genetic adaptations
that allow this microorganism to live and cause decay in the human oral
cavity. The study, led by Marco Ventura's Probiogenomics laboratory at the
University of Parma, and Prof. Douwe van Sinderen and Dr Paul O'Toole of
the Alimentary Pharmabiotic Centre at University College Cork, is
published
December 24 in the open-access journal PLoS Genetics.


Bifidobacteria, largely known as long-term beneficial gut bacteria, are
often included as probiotic components of food to aid digestion and boost
the
immune system. However, not all species within the genus Bifidobacterium
provide beneficial effects to the host's health. In fact, the
Bifidobacterium dentium species is an opportunistic pathogen since it has
been linked to the development of tooth decay. The genome sequence of B.
dentium Bd1 reveals how this microorganism has adapted to the oral
environment through specialized nutrient acquisition features, acid
tolerance,
defences against antimicrobial substances and other gene products that
increase fitness and competitiveness within the oral niche.


This report identifies, through various genomic approaches, specific
adaptations of a Bifidobacterium taxon to a lifestyle as a tooth
decay-causing
bacterium. The data in this study indicate that the genome of this
opportunistic pathogen has evolved through only a small number of
horizontal gene
acquisition events, highlighting the narrow boundary that separates
bacteria that are long-term residents on or in the human body from
opportunistic
pathogens.


Financial Disclosure: This work was financially supported by the Italian
Award for Outstanding Young Researcher scheme Incentivazione alla mobilit? 
di studiosi stranieri e italiani residente all'estero 2005-2009 and a
Marie Curie Reintegration Grant (MERG-CT-2005-03080) to MV; by the Science
Foundation Ireland Alimentary Pharmabiotic Centre located at University
College Cork to DvS, GFF, and PWOT; and by an EMBARK postdoctoral grant to
AZ.
The funders had no role in study design, data collection and analysis,
decision to publish, or preparation of the manuscript.


Competing Interests: The authors have declared that no competing interests
exist.


Citation:

Ventura M, Turroni F, Zomer A, Foroni E, Giubellini V, et al. (2009)

"The Bifidobacterium dentium Bd1 Genome Sequence Reflects Its Genetic Adaptation to the Human Oral Cavity."


PLoS Genet 5(12): e1000785. doi:10.1371/journal.pgen.1000785