(153c) In Situ Mapping of the Mechanical Properties of Sulfate Reducing Bacteria By Microrheology

Sulphate-reducing bacteria (SRB) are corrosive anaerobic bacteria that secrete exopolymers on metal surfaces and form a biofilm to induce uniform corrosion or localized pitting. Quantifying the rheological properties of SRB biofilms at the micron scale is an important step to investigating the communal lifecycles of the bacteria as they adhere to substrate surfaces. The bacteria can modulate the mechanical properties of the biofilm according to the requirements of their colonial lifecycles. Rheology at the micron scale is directly relevant to the resistance of the biofilm from mechanical damage. Passive microrheology is a reasonably well-established technique that can be used to investigate the viscoelasticity of biofilms. Multiple particle-tracking (MPT) relies on tracking the Brownian motion of particles that are embedded in a medium to calculate the mechanical properties of the medium in the vicinity of the particles. By tracking the motion of the particles, measuring the viscoelasticity regarded by individual bacteria is possible. MPT resolves the local mechanical properties of the biofilm hydrogel spatially and temporally. We have developed a set of protocols that utilize MPT to characterize the mechanical properties of anaerobic bacteria in situ. To avoid biofilm disruption and eradication, fluorescent tracer particles are integrated into the media of the biofilms prior to inoculation. The primary contributors to biofilm mechanical properties, contributing to the overall viscoelastic character, have been investigated. The biofilm has been examined at different times after cultivation and under alternate environmental conditions. Our preliminary data confirms the establishment of biofilm growth, while showing different levels of heterogeneity in the biofilm.