ATOMIC FORCE MICROSCOPY INVESTIGATION OF THE BIOFILM POLYSACCHARIDE FROM BURKHOLDERIA MULTIVORANS C1576

摘要

Biofilms (BF) are the most common mode of bacterial life. To setup biofilms bacteria adhere to a surface, or to other cells, and biosynthesize a macromolecular matrix which surrounds the cells, entrapping useful molecules. The major BF matrix components are exopolysaccharides (Epols) which constitute an aqueous gel-like structure. In diseases, BF-associated infections are particularly relevant because they are very difficult to eradicate. Therefore, the mechanisms involved in matrix stability and the role of matrix components in BF functions are important. We investigated the structure of Epols extracted from biofilms of different species of the Burkholderia cepacia Complex, a group of opportunistic pathogens causing serious lung infections. The one produced by B. multivorans strain C1576 (EpolC1576) is constituted by Rha sequences bearing also methyl substituents (Figure 1)[1]. These features suggested a less polar nature of the Epol backbone with respect to other polysaccharides, as proved by its ability to bind aromatic fluorescent probes[2]. In addition, molecular modeling showed that the EpolC1576 forms a flexible random coil conformation in aqueous solution, with transient hydrophobic domains that may accommodate nonpolar guest molecules[2].