Application of FESEM and FTIR for evaluation of Staphylococcus aureus biofilms grown on chitin and polycarbonate membrane

The aim of this study was to use Field Emission Scanning Electron (FESEM) and Fourier transform infrared spectroscopy (FTIR), to investigate the structure and the film-forming capacity of Staphylococcus aureus, on two different surface materials, Chitin and Polycarbonate membrane filter. Both the substrates, having diverse properties, showed varied attachments of bacterial and biofilm development. FESEM showed that higher bacterial colonization and biofilm growth was obtained in the rough surface of chitin with complex structure, compared to that of polycarbonate membrane at different time intervals. Due to its high magnification and resolution, FESEM enabled a more detailed analysis of the biofilm cells, influenced by different structural organisations and morphology.  On the other hand, FTIR analyses revealed the chemical conformation of the substrate and its biofilm state. However, the difference in the spectra of the two substrates was not large. Prominent band absorbance at 1200-800 cm-1 for polysaccharides and proteins at 1700- 1400 cm-1 were observed at its biofilm states. These findings promote the prospect of using FESEM and FTIR for understanding biofilm morphology and architecture, as well as its chemical interaction with the substrate.