Understanding Bacterial Biofilm Stimulation Using Different Methods - a Criterion for Selecting Epiphytes by Plants

Earlier studies by our group revealed that gallic acid in phytochemicals stimulated biofilm production in epiphytes, while caffeic acid in phytochemicals inhibited biofilm production in non-epiphytes. It is well documented that antimicrobial secretion by some epiphytic bacteria inhibits non-epiphytic bacterial growth on leaf surfaces. These selection criteria help plants choose their microbial inhabitants. Calcium and iron in phytochemicals also stimulate biofilm formation and thus, may be selection criteria adopted by plants with respect to their native epiphytic population. Furthermore, the processing of leaves during phytochemical extraction impacts the composition of the extract, and therefore its ability to affect bacterial biofilm formation. Computation of the Hurst exponent using biofilm thickness data obtained from the Ellipsometry of Brewster Angle Microscopic (BAM) images is an efficient tool for understanding the impact of phytochemicals on epiphytic and non-epiphytic populations when compared to fluorescent microscopy, scanning electron microscopy, and staining techniques. To the best of our knowledge, this is the first report that uses the Hurst exponent to elucidate the mechanism involved in plant microbe interaction.