Motility of Bacteria in a synthetic Yield-Stress Fluid

Understanding the dynamics of bacteria in yield-stress fluids presents an intriguing opportunity for studying microbial locomotion in biological fluids and its underlying mechanisms, as many of these fluids possess a yield stress. The yield-stress fluid chosen is a well-dispersed aqueous suspension of hairy nanoparticles (HNPs), which is made of covalently tethered poly (ethylene glycol) methyl ether (mPEG) on silica nanoparticles. The selection of aqueous HNPs as our yield-stress fluid stems from their rheological similarities to mucus and the fact that they are made of accessible, bio-compatible materials. Moreover, unlike mucus, which has variant rheology due to the degradation of samples and natural variability between patients, HNPs rheology is reproducible, allowing us to study bacterial motility systematically. We will present our results concerning bacteria's growth and survival rates in HNPs solutions. Moreover, we will show our primary results focusing on the motility of bacteria using a single particle tracking method. Specifically, we aim to understand the variation of the mean speed and velocity fluctuations of bacteria with the yield stress in dilute bacterial suspensions.