Agar is a complex mixture of polysaccharides. It is widely used in microbiology as a jellifying agent to obtain solid culture medium that can then support the growth of bacteria, yeasts and other microorganisms. Although this substrate has a daily use in biology and microbiology, its physico-chemical properties are still not well known. Consequently, a characterisation of a solid bacteriological medium infected or not by Escherichia coli type bacteria can be realized on thin films obtained by spin coating.
The present study using a prism coupler method gives a sensitive tool to detect photo-physical change in the medium. This method could allow us to detect the presence of bacteria. Results obtained are reproducible on different samples and might be qualitatively compared with conventional imagery.
This method should enable a rapid detection of the growing of bacteria on the studied medium.