A SIMPLE IN-VITRO MODEL FOR GROWTH-CONTROL OF BACTERIAL BIOFILMS

The perfused biofilm fermenter was found to be unsuitable for the long -term culture and growth rate control of Staphylococcus aureus and Pse udomonas aeruginosa biofilms. In a simplified approach, biofilms of th ese organisms were grown within Sorbarod filter plugs which were perfu sed with culture medium. Pseudo-steady states were established which w ere stable over several days at which the growth rate of the biofilm w as reproducible, measurable and significantly slower than in broth cul ture. Environmental scanning electron microscopy of dissected Sorbarod s demonstrated an association of cells with the surfaces of individual cellulose fibres, and growth characteristic of biofilms. Relatively h igh cell numbers recovered from the Sorbarod model facilitated biochem ical investigations of biofilm populations and cells released spontane ously from them. SDS-PAGE demonstrated significant differences between the protein profiles of biofilm and eluted populations, which include , in Staph. aureus, the repression of a 48 kDa protein and increased e xpression of a 21 kDa protein relative to planktonic controls cultured at equivalent growth rates. The paper demonstrates the suitability of the approach for the culture of biofilm samples which are suitable fo r biochemical analysis.