Scanning Transmission X-Ray, Laser Scanning, and Transmission Electron Microscopy Mapping of the Exopolymeric Matrix of Microbial Biofilms

J. R. Lawrence, G. D. W. Swerhone
National Water Research Institute, Saskatoon, Saskatchewan, Canada S7N 3H51

G. G. Leppard
NWRI, Burlington, Ontario, Canada L7R 4A62

T. Araki, X. Zhang, A. P. Hitchcock
Brockhouse Institute for Materials Research, McMaster University, Hamilton, Ontario, Canada L8S 4M13

M. M. West
Electron Microscopy Facility, Faculty of Health Sciences, McMaster University, Hamilton, Ontario, Canada L8N 3Z54

Received 3 April 2003/Accepted 29 June 2003

Confocal laser scanning microscopy (CLSM), transmission electron microscopy (TEM), and soft X-ray scanning transmission X-ray microscopy (STXM) were used to map the distribution of macromolecular subcomponents (e.g., polysaccharides, proteins, lipids, and nucleic acids) of biofilm cells and matrix. The biofilms were developed from river water supplemented with methanol, and although they comprised a complex microbial community, the biofilms were dominated by heterotrophic bacteria. TEM provided the highestresolution structural imaging, CLSM provided detailed compositional information when used in conjunction with molecular probes, and STXM provided compositional mapping of macromolecule distributions without the addition of probes. By examining exactly the same region of a sample with combinations of these techniques (STXM with CLSM and STXM with TEM), we demonstrate that this combination of multimicroscopy analysis can be used to create a detailed correlative map of biofilm structure and composition. We are using these correlative techniques to improve our understanding of the biochemical basis for biofilm organization and to assist studies intended to investigate and optimize biofilms for environmental remediation applications.