Bacterial floc mediated rapid streamer formation in creeping flows.
One of the central puzzles concerning the interaction of low Reynolds number fluid transport with bacterial biomass is the formation of filamentous structures called streamers. In this manuscript, we report our discovery of a new kind of low Re bacterial streamers, which appear from pre-formed bacterial flocs. In sharp contrast to the biofilm-mediated streamers, these streamers form over extremely small timescales (less than a second). Our experiments, carried out in a microchannel with micropillars rely on fluorescence microscopy techniques to illustrate that floc-mediated streamers form when a freely-moving floc adheres to the micropillar wall and gets rapidly sheared by the background flow. We also show that at their inception the deformation of the flocs is dominated by recoverable large strains indicating significant elasticity. These strains subsequently increase tremendously to produce filamentous streamers. Interestingly, we find that these fully formed streamers are not static structures and show viscous response at time scales larger than their formation time scales. Finally, we show that such novel streamer formation can lead to rapid clogging of microfluidic devices.
Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Canada.
Mahtab
M
Hassanpourfard
Department of Mechanical Engineering, University of Alberta, Edmonton, Canada.
Zahra
Z
Nikakhtari
Department of Mechanical and Industrial Engineering, Northeastern University, Boston MA 02115, USA.
Ranajay
R
Ghosh
Department of Mechanical Engineering, University of Maryland, College Park, MD 20742, USA.
Siddhartha
S
Das
Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Canada.
Thomas
T
Thundat
Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Canada.
Yang
Y
Liu
Department of Mechanical Engineering, University of Alberta, Edmonton, Canada.
Aloke
A
Kumar
D001419:Bacteria / Q000378:metabolism*; D001422:Bacterial Adhesion / Q000502:physiology; D018441:Biofilms; D004548:Elasticity; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation / Q000379:methods*; D008856:Microscopy, Fluorescence; D018715:Microscopy, Video; D011551:Pseudomonas fluorescens / Q000502:physiology
D049452:Green Fluorescent Proteins