Oral anaerobes cannot survive oxygen stress without interacting with facultative/aerobic species as a microbial community

Anaerobic bacteria are found commonly as components of mixed culture biofilms in many aerated habitats, including the mouth. Previous studies showed that anaerobes could survive in planktonic and biofilm communities in aerated conditions when part of a community including facultative and/or aerobic species, and the numbers and proportions of anaerobic species increased as biofilms aged. When the obligate anaerobes were grown in the absence of aerobic/facultative species, however, they were unable to grow in either the planktonic or biofilm culture. The mean survival times of organisms in the aerated culture containing four anaerobic species varied from around 5 min for Fusobacterium nucleatum and Veillonella dispar, to less than 4 min for Porphyromonas gingivalis and Prevotella nigrescens. In addition, in this culture, the biofilm mode of growth did not provide a haven for these bacteria in the absence of oxygen-consuming species.