Laser Scanning Confocal Microscopy (LSCM) study of
surface properties of biofilm coated sand particles
Bayer, J.1*, Cheng, S.1,2, Bryant, R. 1, Doerr, S.H.2, Wright, C.1
1
School of Engineering, University of Wales Swansea, Singleton Park, Swansea
SA2 8PP, UK. *Juliabayer@gmx.net
2 School of Environment and Society, University of Wales Swansea, Singleton Park,
Swansea SA2 8PP, UK.
Plant root and fungal exudates are known to have a great impact to soil-water
interactions and represent an important component of soil organic matter (SOM). The
amount of these exudates, that are known to influence the soil-water interaction,
appear not to correlate directly with the hydrological behaviour of soils, e.g. the
degree of water repellency. Therefore, it is suggested that distribution and orientation
of exudate molecules is more important than the quantity present in the soil.
Laser Scanning Confocal Microscopy (LSCM) has been used widely to image
cells or neural networks. Either the fluorescence of dyes binding to the structures of
interest or the autofluorescence of the sample can be imaged. As LSCM has a very
high resolution even single cells can be imaged and scanned through a sequence of
optical planes allows 3D images to be obtained.
Biomolecules are often composed of large ring structures with large
conjugated π-systems and, therefore, often show autofluorescence. Where these do
not show autofluorescence, dyes binding to special functional groups, such as
carboxylic or phenolic groups, can be used to assist imaging.
This study investigates the correlation between distribution of plant root and
fungal exudates on sand particle surfaces and their water repellency. Clean sand
particles were coated with different biological exudates and humic acid in different
concentrations. Individual sand particle surfaces were investigated by LSCM and
Atomic Force Microscopy (AFM). The water repellency of bulk material was assessed
by the water drop penetration time (WDPT) test.