The opportunistic pathogenic mould Aspergillus fumigatus (A. fumigatus) is an increasing cause of morbidity
and mortality in immunocompromised and in part immunocompetent patients. A. fumigatus can grow
in multicellular communities by the formation of a hyphal network embedded in an extracellular matrix
(ECM) meanly composed by polysaccharides, melanin, proteins. Because adhesion properties is one primary
factor affecting the balance between growth, detachment and biofilm formation, its quantification
is essential in understanding, predicting, and modelling biofilm development.
Atomic force microscopy (AFM) imaging and force spectroscopy have recently opened a range of novel
applications in microbiology including the imaging and manipulation of membrane proteins at the subnanometer
level, the observation of the surface of living cells at high resolution, the mapping of local
properties such as surface charges, the measurement of elastic properties of cell-surface constituents
and the probing of cellular interactions using functionalized probes. Nevertheless, the principal disadvantage
of this approach is the relatively slow acquisition rate that makes AFM is not able to detect fast
In this study we demonstrated that digital pulsed force mode (DPFM) atomic force microscopy can be
used to obtain high-resolution topographical images and to quantify the adhesion properties of the A.
fumigatus biofilm with an high acquisition rate.
Here we show by means of DPFM-AFM that Alginate Lyase (AlgL), an enzyme known to reduce negatively
charged alginate levels in microbial biofilm, is able to reduce the biofilm adhesion forces forming
several nano-fractures in the ECM. These results suggest that the AlgL could used to enhance the antifungal
drugs transit through the ECM.
- Aspergillus fumigatus