Nanoscale interactions of candida species with oral bacteria and surfaces

The human mouth contains many different types of microorganisms that are often found attached to oral surfaces in 'sticky' communities called biofilms. These microorganisms are held in close proximity and will therefore likely influence the behaviour of each other. The effects of this could result in increased microbial growth, the displacement of some microorganisms to other sites, the alteration of gene expression and potentially, the enabling of microorganisms to cause infection.
A PhD research project being done by Ms Megan Williams at the School of Dentistry, Cardiff University has been exploring how a fungus called Candida albicans can interact both with acrylic surfaces (used to manufacture dentures) and also with bacterial species often found alongside Candida albicans. To date, the work has indicated that colonisation of acrylic coated with different fluids, including those generated from tobacco smoking, may change the way Candida albicans grows. Candida albicans can grow as round cells called yeast, or as filamentous forms called hyphae. It is the hyphal forms that are often considered more damaging to human tissue surfaces during infection. In addition, the research shows that when certain bacteria are grown on acrylic surfaces with Candida albicans, hyphal development is also triggered. This is important, as it may mean that occurrence of infection by Candida albicans is at least in part determined by the community composition of the bacteria present alongside Candida.
To date, the methods used to study these effects have included fluorescent microscopy, where the Candida is stained to fluoresce a different colour to bacteria and the surface of attachment. Whilst this approach allows quantification of attachment and imaging of the different growth forms, it cannot determine strength of cell-cell-surface interactions.
Atomic Force Microscopy (AFM) is a method that provides images through measuring forces acting between a moving probe and a surface. It is possible to attach different molecules and even whole bacteria to the AFM probe, and in doing so, we can measure interactions occurring between bacteria, and either Candida yeast or hyphae serving as the substrate.
Dr Laurent Bozec and his team at the University of Toronto are experts in use of AFM, which is not available in the School of dentistry, Cardiff. The exchange therefore offers the PhD student the opportunity to learn a new experimental technique, generate important data for the PhD and benefit from unique networking experiences. The results generated from this proposal will greatly enhance the research output and complement existing findings of the PhD. Ultimately, this could help determine how bacteria physically interact with Candida albicans and trigger the development of hyphal filaments to facilitate infection.