Corner Flows Induced by Surfactant-Producing Bacteria Bacillus subtilis and Pseudomonas fluorescens

Yuan Li, Joseph E. Sanfilippo, Daniel Kearns, Judy Q. Yang

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


A mechanistic understanding of bacterial spreading in soil, which has both air and water in angular pore spaces, is critical to control pathogenic contamination of soil and to design bioremediation projects. A recent study (J. Q. Yang, J. E. Sanfilippo, N. Abbasi, Z. Gitai, et al., Proc Natl Acad Sci U S A 118:e2111060118, 2021, pnas.2111060118) shows that Pseudomonas aeruginosa can self-generate flows along sharp corners by producing rhamnolipids, a type of biosurfactants that change the hydrophobicity of solid surfaces. We hypothesize that other types of biosurfactants and biosurfactant-producing bacteria can also generate corner flows. Here, we first demonstrate that rhamnolipids and surfactin, biosurfactants with different chemical structures, can generate corner flows. We identify the critical concentrations of these two biosurfactants to generate corner flow. Second, we demonstrate that two common soil bacteria, Pseudomonas fluorescens and Bacillus subtilis (which produce rhamnolipids and surfactin, respectively), can generate corner flows along sharp corners at the speed of several millimeters per hour. We further show that a surfactin-deficient mutant of B. subtilis cannot generate corner flow. Third, we show that, similar to the finding for P. aeruginosa, the critical corner angle for P. fluorescens and B. subtilis to generate corner flows can be predicted from classic corner flow theories. Finally, we show that the height of corner flows is limited by the roundness of corners. Our results suggest that biosurfactant-induced corner flows are prevalent in soil and should be considered in the modeling and prediction of bacterial spreading in soil. The critical biosurfactant concentrations we identify and the mathematical models we propose will provide a theoretical foundation for future predictions of bacterial spreading in soil.

Original languageEnglish (US)
JournalMicrobiology Spectrum
Issue number5
StatePublished - Sep 2022

Bibliographical note

Funding Information:
This research was supported by J. Q. Yang’s startup fund and the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources (LCCMR). Y. Li was supported by the fellowship of Civil, Environmental, and Geo-Engineering at the University of Minnesota. J. Sanfilippo was supported by NIH grant no. K22 AI151263. D. Kearns was supported by NIH grant no. R35 GM131783. We thank Mohamed Donia (Princeton University) for sharing with us the bacterial strain Pseudomonas fluorescens PF15.

Publisher Copyright:
© 2022 Li et al.


  • Bacillus subtilis
  • bacterial spreading
  • biosurfactant
  • contact angle
  • corners
  • hydrocarbons
  • hydrophobicity
  • Pseudomonas fluorescens
  • rhamnolipids
  • soil
  • soil microbiology
  • surfactin

PubMed: MeSH publication types

  • Journal Article
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't


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