Development of a Steady-State Oral Microbial Biofilm Community using the Constant-Depth Film Fermenter

1 School of Pure and Applied Biology, University of Wales College of Cardiff, Cardiff CF1 3TL, UK 2 Department of Basic Dental Science, University of Wales College of Medicine, Cardiff CF4 4XY, UK 3 Centre for Applied Microbiology and Research, Salisbury SP4 OJG, UK * Author for correspondence: Julian W. T. Wimpenny. Tel: +44 1222 874974. e-mail: sabjw@cardiff.ac.uk ABSTRACT The complexity of biofilm communities like dental plaque suggests that laboratory model biofilm growth systems may help to understand their structure and function. This study describes the use of a constant-depth film fermenter (CDFF) to investigate biofilm formation by a nine-membered community of oral bacteria. The community was grown to steady state in a chemostat incubated anaerobically. The chemostat output was fed into the CDFF incubated aerobically. Viable counts for each species from the chemostat and the CDFF at steady state showed major differences; however, all nine organisms were present under both conditions. There was evidence of succession during biofilm formation with obligately anaerobic species only establishing after several days. A steady-state biofilm community was achieved which remained stable over time. Electron microscopy showed evidence of spatial differentiation with what appeared to be Neisseria subflava dominant near the upper surface and Fusobacterium nucleatum largely confined to the middle portion. Keywords: steady state, biofilm, community, oral, growth