, 2010). It was also shown that deletion of cspA (cell surface protein A), which encodes a repeat-rich glycophosphatidylinositol-anchored cell wall protein, causes weakening

of the conidial cell wall (Levdansky et al., 2010). Analysis of double mutants indicated that cspA interacts with Regorafenib molecular weight the cell wall protein-encoding genes EPS33 and Gel2, deletion of which results in strongly reduced conidial adhesion, increased disorganization of the conidial cell wall and exposure of the underlying layers of chitin and beta-glucan. Given the number of genes integral to adhesion and cell wall structure, it is likely that many play a pivotal role in the different phases of biofilm formation, and as biofilm becomes an accepted term within the Aspergillus research community, Selleckchem AZD6244 many future studies

will elucidate the molecular pathways for its development. The initial clinical-based studies explored whether A. fumigatus multicellular structure (or mycelial mass) fits the criteria for a biofilm, and represents a source of continuing debate (Chandrasekar & Manavathu, 2008; Mowat et al., 2008a). A key factor as observed early in our investigations was the critical importance of conidial seeding density, a phenomenon also described in studies of A. niger biofilms (Villena & Gutierrez-Correa, 2006). Confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) demonstrated an optimal conidial seeding density of 1 × 105 conidia mL−1 of liquid medium. Therefore, structural morphology and integrity was dependent upon the concentration of conidia

(Mowat et al., 2007). This biofilm system was then amenable to high throughput testing required for the screening of clinical isolates and defined mutants, or for testing the susceptibility of antifungal agents (Mowat et al., 2008b). This concentration differs from those described elsewhere, where it was reported than an optimized conidial density of 1 × 106 per millilitre was used, a concentration also reported within an epithelial-biofilm co-culture system (Villena & Gutierrez-Correa, 2006; Seidler et al., 2008). However, this log difference was due to subtleties of biofilm model systems, which both utilize different substrates and media. Fungal biofilms, like bacterial biofilms, have defined developmental phases that include arrival at an appropriate substrate, adhesion, colonization, polysaccharide Epothilone B (EPO906, Patupilone) production, and biofilm maturation and dispersal (Chandra et al., 2001; Donlan, 2002; Blankenship & Mitchell, 2006). Both CLSM and SEM were used in our investigations to evaluate the characteristics of this development. Following initial conidial seeding, there is a lag phase (conidial adhesion), germination (6–8 h), filamentation and formation of a monolayer (12 h), followed by increased structural complexity, EPS production and maturation (24 h). During this time, the depth of the biofilm increases from 10 to 200 μm (Mowat et al., 2007).