A major problem that develops with implanted biomedical devices is that they become covered with biofilms that are made by microbes such as the fungus Candida albicans. The properties of biofilms make it difficult to defend against such infections, even with antifungals. Candida initially grow on surfaces as typical yeast-form cells and then mature into hyphal-like structures bearing adhesins and forming an extensive extracellular matrix of carbohydrate and protein.
Nobile et al. have been investigating the regulation of Candida biofilm formation. After their discovery that hyphal development and adhesion are coupled via Tec1 control of Bcr1, they find that adhesin expression is the specific target of Bcr1 in vivo. Yeast mutants deficient in BCR1 cannot form biofilms on polyethylene catheters implanted in rats but can be rescued if an adhesin-encoding gene, ALS3, is overexpressed. Interestingly, als3/als3 mutants do form biofilms, probably because other adhesins, including those similar to mating agglutinins, are under the influence of BCR1 in this network and can compensate. -- CA
PloS Pathol. 2, e63 (2006).
