(B-75) Observing Flow Patterns at the Fluid-Biofilm Interface for Marine Bacteria Biofilms Designed for Aquatic Use

Introduction:: Bacteria biofilms are comprised of a single colony or co-colonies of bacteria grown to cover a surface. In many applications, bacteria growth is trying to be prevented, but bacteria biofilms can have beneficial applications if the growing conditions can be controlled. One use of biofilms is for covering small marine vessels to prevent the growth of undesired marine life that will hinder the performance of the vessels. For a biofilm to be used in this environment, it must survive in a marine environment and provide little impedance to function while rejecting marine life attachment. To test which bacteria will work for this application, the bacteria must be grown in a turbulent, aqueous environment and the disturbance of flow must be measured. To perform these measurements, optical coherence tomography (OCT) can be used to capture xz plane images of the bacteria and the surrounding fluid. OCT can detect the thickness and roughness of the biofilm and capture the movement of particles in the growth media to observe flow patterns near the biofilm-fluid interface.


Materials and Methods:: A testbed was developed to mimic the environment that the biofilms will be operating in. The setup consists of fluid pumps that move low-nutrient media through a growth chamber in which the bacteria is allowed to grow and form a biofilm over the surface. A custom-built OCT system was designed using a supercontinuum light source and a weakly focused objective. The data was captured using an 1800 lines/mm diffraction grating and 4096-pixel line scan camera. OCT imaging was performed on these bacteria biofilms to capture the thickness and surface characteristics of the biofilm. The media was seeded with small particles to provide markers of fluid flow for the OCT. Using OCT-based particle image velocimetry (PIV), the fluid patterns were able to be visualized near the surface of the biofilms.


Results, Conclusions, and Discussions:: The flow patterns at the biofilm-fluid interface were able to be properly visualized using PIV techniques. Changes could be detected for different biofilm growth patterns. This is confirmation that this technique can be used to observe and assess biofilm growth for later use on marine vessels. The upcoming steps will be to create algorithms to provide quantitative estimates of the turbulence at the biofilm surface. These results will be combined with measurements of biofilm sand roughness to determine the impact that different biofilms will have on the performance of the marine vessels that these biofilms are intended for.


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