Towards chemical analysis of nanostructures in biofilms I: imaging of biological nanostructures
Due to their direct influence on the stability of bacterial biofilms, a better insight into the nanoscopic spatial arrangement of the different extracellular polymeric substances (EPS), e.g., polysaccharides and proteins, is important for the improvement of biocides and for process optimization in wastewater treatment and biofiltration. Here, the first application of a combination of confocal laser-scanning microscopy (CLSM) and atomic force microscopy (AFM) to the investigation of river-water biofilms and related biopolymers is presented. AFM images collected at selected areas of CLS micrographs dramatically demonstrate the heterogeneity of biofilms at the nanometer scale and the need for a chemical imaging method with nanoscale resolution. The nanostructures (e.g., pili, flagella, hydrocolloids, and EPS) found in the extracellular matrix are classified according to shape and size, which is typically 50–150 nm in width and 1–10 nm in thickness, and sets the demands regarding spatial resolution of a potential chemical imaging method. Additionally, thin layers of the polysaccharide alginate were investigated. We demonstrate that calcium alginate is a good model for the EPS architecture at the nanometer scale, because of its similar network-like structure.
KeywordsBiofilm Extracellular polymeric substances (EPS) Alginate Confocal laser-scanning microscopy (CLSM) Atomic force microscopy (AFM)
Financial support for our work from the Deutsche Forschungsgemeinschaft (to Thomas Schmid), the ETH Zürich, and the Gebert Rüf Stiftung (grant no. P-085/03) is greatly appreciated.
- 3.O’Flaherty V, Moran AP, Stoodley P, Mahony T, Lens P (2003) Biofilms in medicine, industry and environmental biotechnology - characteristics, analysis and control. IWA, LondonGoogle Scholar
- 7.Sutherland IW (2001) Microbiol-UK 147:3–9Google Scholar
- 9.Bishop PL, Wilderer PA, Wuertz S (2003) Biofilms in wastewater treatment - an interdisciplinary approach. IWA, LondonGoogle Scholar
- 18.Hansma PK, Walters DA, Hillner PE (1996) US Patent 5,581,082Google Scholar
- 19.Hillner PE, Walters DA, Lal R, Hansma HG, Hansma PK (1995) Microsc Microanal 1:127–130Google Scholar
- 22.Schmid T, Messmer A, Yeo BS, Zhang W, Zenobi R (2008) Anal Bioanal Chem, DOI 10.1007/s00216-008-2101-1
- 27.Schmid T, Yeo BS, Zhang W, Zenobi R (2007) Use of tip-enhanced vibrational spectroscopy for analytical applications in chemistry, biology, and materials science. In: Kawata S, Shalaev V (eds) Tip Enhancement. Elsevier, AmsterdamGoogle Scholar
- 39.Evans LR, Linker A (1973) J Bacteriol 116:915–924Google Scholar