Biofilms 2012

Project of S. Reuben and S. Swarup (Singapore-Delft Water Alliance National University of Singapore.)

Biofilms are aggregations of microorganisms embedded in extrapolymeric substances (EPS). Their structure and composition vary in the different ecological conditions and with their maturity. Visualization of microorganisms is critical in gaining an insight into their function in the biofilm community and microbial interrelationships within the biofilms. Though researchers have attempted to understand biofilm compositional heterogeneity in cultured cells, insight into spatial heterogeneity of natural biofilms is limited. Fourier Transform Infrared (FTIR) imaging and, in particular, spectromicroscopy, can be considered as a non-destructive chemical mapping where each pixel within an image corresponds to a complete FTIR spectrum that reflects the chemical composition at the analyzed spot. Many common biomolecules, such as nucleic acids, carbohydrates, proteins and lipids have characteristic and well-defined IR-active vibrational modes. Using Singapore Synchrotron Light Source ISMI beamline and the high brilliance of the synchrotron radiation edge effect source it is possible to analyze samples in greater spatial resolution and chemical details. Early biofilms were grown on various substrates in water from a storm water canal (Sungei Ulu Pandan). Two-day biofilms were then directly imaged and analyzed in situ. Several substrates were tested for two criteria 1) ability to grow biofilms 2) compatibility with FTIR spectroscopy.

Preliminary results reveal that the analysis of biofilms by means of FTIR is a major challenge, firstly because of finding proper supporting material to prepare the sample to experiments and secondly because of the strong water absorption in the mid-infrared region. The first FTIR spectra collected for biofilm grown on Mylar foil seem to be reasonable for the initial analysis. The full understanding of any diversities in biofilms species during their growing processes available by analysis of their FTIR spectra require further detailed and monitored studies and interpretations, but we believe that this method will provide better insight into the dynamic of biofilm structures and functions.