Speaker
Description
Bacterial biofilms play a crucial role in environmental and engineering porous media, affecting flow, solute transport, and contaminant degradation. Understanding the interplay between bacterial biofilms and the structural heterogeneity of porous media, as well as the effect of water flow conditions, is fundamental for modeling these processes. Additionally, the impact of various biofilm extracellular components on biofilm growth dynamics remains largely unexplored. It could aid in understanding the functions of biofilms in various systems or even tailor specific types of bacteria for different purposes. In this work, we study the effects of biofilm characteristics and porous medium structure on biofilm growth dynamics. We use microfluidic porous medium devices with specifically designed structures and inoculate them with Bacillus Velezensis, a model Plant Growth Promoting Rhizobacteria (PGPR). We use a wild-type strain and a $\Delta$tasA strain mutant in extracellular protein fiber formation. The microfluidic porous medium devices feature an array of circular pillars within a rectangular channel, mimicking the structure of a porous medium. This structure is governed by the variance in pillar diameter distribution, which controls pore-scale heterogeneity. We initiate our experiments by inoculating the porous medium with a bacterial culture solution. We then inject nutrient broth into the microfluidic chip at a constant flow rate while periodically capturing images of biofilm development using a microscope in Brightfield mode. Biofilm growth limits the intensity of the light passing through it, therefore allowing us to quantify biofilm development in space and time. We also calculate the detailed distribution of pore and throat sizes, and numerically calculate the liquid velocity field within the porous medium. Preliminary results reveal higher biofilm accumulation in smaller pores during the early to moderate stages of the experiment, indicating that biofilm formation may initially favor smaller pores where velocities are relatively low. Ongoing experiments are designed to investigate the effects of varying flow rates, and hence the Péclet number, on biofilm formation and how the interplay between solute transport and fluid shear stress influences it.
| Country | Israel |
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