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 mobilità 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.