, 2010). Recent work has used RNA-Seq to compare the transcriptomes of biofilm and liquid planktonic growth, where sequencing identified 3728 differentially regulated genes in the two conditions (Gibbons et al., 2011). In addition to many genes that are likely to reflect the different growth demands, these investigations identified many up-regulated genes involved in transport, secondary metabolism and cell wall and surface functions. Mapping of these genes showed significant spatial structure across the genome.
A total of 1164 genes were down-regulated, which were involved in primary metabolic functions, including carbon and amino acid metabolism. Interestingly, these were not spatially structured across the genome. This work has provided some initial insight into the genetics of biofilm formation. Evaluation of differential gene expression in A. niger biofilms formed on polyester cloth was performed. It was shown that genes encoding Etoposide some
lignocellulolytic enzymes and some regulatory genes showed that eng1, eglA, eglB, eglC, exo and xynB genes (coding for endoglucanases, a cellobiohydrolase GSK2126458 and a xylanase respectively) are differentially expressed in biofilm fermentation. Likewise, the regulatory genes xlnR (cellulase activator) and creA (cellulase repressor) showed time-related expression patterns, indicating that a different regulatory system may act in biofilms (Villena et al., 2009a). The intracellular proteome of A. niger biofilms was recently compared with that of the conventionally grown free-living submerged cultures. In biofilm
cultures, 19% and 32% of the selected protein spots were over-expressed and differentially expressed, respectively, compared to 44% and 7%, respectively, in free-living cultures (Villena et al., 2009b). It was demonstrated that A. niger biofilms differentially expressed a putative calcium P-type ATPase, which is important both in the homoeostatic selleck compound maintenance of calcium concentration in the endoplasmic reticulum, and in cation-dependant functions of Golgi apparatus (Vashist et al., 2002); this protein is probably involved in cAMP-mediated signalling (Bencina et al., 2005). Biofilms require the production of an EPS to satisfy the basic definition, which provides protection from hostile factors, such as host immunity and antifungal agents (Ramage et al., 2009). The presence of extracellular hydrophobic matrix composed of galactomannan, alpha-1,3 glucans, monosaccharides, polyols, melanin and proteins including major antigens and hydrophobins in an aerial static A. fumigatus biofilm model was recently demonstrated (Beauvais et al., 2007). This model was developed to study the characteristics of a fungus ball, opposed to using the typical submerged shaking culture system. Within the ball, hyphae are agglutinated and collectively form a macrocolony of highly branched hyphal elements that are tightly associated with one another.