Microbial Interactions Within Denture Biofilms

Most microorganisms naturally grow within biofilms in both environmental and industrial systems. Biofilms on denture surfaces are widely acknowledged and arise in cases of poor oral/denture hygiene and where dentures are not removed whilst sleeping.

Key microorganisms in denture biofilms include fungi of the genus Candida as well as bacteria that can originate from other oral sites or from exogenous sources. The majority of denture biofilm studies have targeted Candida as these fungi are highly adept at adhering to denture acrylic and can induce the infection, denture associated stomatitis. Denture biofilms are, however, ideal for investigating microbial interactions since they are readily accessible, polymicrobial and variable in their microbial composition and can be modelled in vitro.

Furthermore, difference in conditioning of the denture surface may also lead to differential species colonisation and biofilm behaviour. Preliminary studies in our School of Dentistry have highlighted the effect that bacterial species may have on denture biofilm composition and behaviour of Candida albicans.

We have found that Candida growth can be inhibited in biofilms by Pseudomonas aeruginosa, whilst other bacteria, such as certain streptococcal species can influence the morphologyof C. albicans. The reasons for these effects remain unclear, but could be due to specific associations between species, or a feature of a wider community effect on the biofilm.

Project aims
The aims of this PhD are therefore to explore the types and mechanism(s) of microbial interactions that occur in biofilms, using denture biofilms as model systems.