Rapid formation of bioaggregates and morphology transition to biofilm streamers induced by pore-throat flows

Sang Hyun Lee, Eleonora Secchi, Peter K. Kang

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Bioaggregates are condensed porous materials comprising microbes, organic and inorganic matters, and water. They are commonly found in natural and engineered porous media and often cause clogging. Despite their importance, the formation mechanism of bioaggregates in porous media systems is largely unknown. Through microfluidic experiments and direct numerical simulations of fluid flow, we show that the rapid bioaggregation is driven by the interplay of the viscoelastic nature of biomass and hydrodynamic conditions at pore throats. At an early stage, unique flow structures around a pore throat promote the biomass attachment at the throat. Then, the attached biomass fluidizes when the shear stress at the partially clogged pore throat reaches a critical value. After the fluidization, the biomass is displaced and accumulated in the expansion region of throats forming bioaggregates. We further find that such criticality in shear stress triggers morphological changes in bioaggregates from rounded- to streamer-like shapes. This knowledge was used to control the clogging of throats by tuning the flow conditions: When the shear stress at the throat exceeded the critical value, clogging was prevented. The bioaggregation process did not depend on the detailed pore-throat geometry, as we reproduced the same dynamics in various pore-throat geometries. This study demonstrates that pore-throat structures, which are ubiquitous in porous media systems, induce bioaggregation and can lead to abrupt disruptions in flow.

Original languageEnglish (US)
Article numbere2204466120
JournalProceedings of the National Academy of Sciences of the United States of America
Volume120
Issue number14
DOIs
StatePublished - Apr 4 2023

Bibliographical note

Funding Information:
ACKNOWLEDGMENTS. This work was supported by MnDRIVE Advancing Industry, Conserving Our Environment at the University of Minnesota, and preparation of PDMS microfluidic devices were conducted in the Minnesota Nano Center, which is supported by the NSF through the National Nano Coordinated Infrastructure Network (NNCI) under Award Number ECCS-2025124. We would like to thank Prof. William Harcombe and Dr. Jeremy Chacon in the College of Biological Sciences at the University of Minnesota for kindly donating the E. coli and M. extorquens strains.

Publisher Copyright:
Copyright © 2023 the Author(s).

Keywords

  • bioaggregate
  • clogging
  • critical shear stress
  • microfluidics
  • pore-throat flows

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