Motility Modulates the Partitioning of Bacteria in Aqueous Two-Phase Systems
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arXiv
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| Format: | Preprint |
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2024
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| author | Cheon, Jiyong Choi, Kyu Hwan Modica, Kevin J. Mitchell, Robert J. Takatori, Sho C. Jeong, Joonwoo |
| author_facet | Cheon, Jiyong Choi, Kyu Hwan Modica, Kevin J. Mitchell, Robert J. Takatori, Sho C. Jeong, Joonwoo |
| contents | We study the partitioning of motile bacteria in an aqueous two-phase mixture of dextran (DEX) and polyethylene glycol (PEG), which can phase separate into DEX-rich and PEG-rich phases. While non-motile bacteria partition exclusively into the DEX-rich phase in all conditions tested, we observed that motile bacteria penetrate the soft DEX/PEG interface and partition variably among the two phases. For our model organism \textit{Bacillus subtilis}, the fraction of motile bacteria in the DEX-rich phase increased from 0.58 to 1 as we increased DEX composition within the two-phase region. We hypothesized that the chemical affinity between DEX and the bacteria cell wall acts to weakly confine the bacteria within the DEX-rich phase; however, motility can generate sufficient mechanical forces to overcome the soft confinement and propel the bacteria into the PEG-rich phase. Using optical tweezers to drag a bacterium across the DEX/PEG interface, we demonstrate that the overall bacteria partitioning is determined by a competition between the interfacial forces and bacterial propulsive forces. Our measurements are supported by a theoretical model of dilute active rods embedded within a periodic soft confinement potential. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2405_08995 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Motility Modulates the Partitioning of Bacteria in Aqueous Two-Phase Systems Cheon, Jiyong Choi, Kyu Hwan Modica, Kevin J. Mitchell, Robert J. Takatori, Sho C. Jeong, Joonwoo Soft Condensed Matter We study the partitioning of motile bacteria in an aqueous two-phase mixture of dextran (DEX) and polyethylene glycol (PEG), which can phase separate into DEX-rich and PEG-rich phases. While non-motile bacteria partition exclusively into the DEX-rich phase in all conditions tested, we observed that motile bacteria penetrate the soft DEX/PEG interface and partition variably among the two phases. For our model organism \textit{Bacillus subtilis}, the fraction of motile bacteria in the DEX-rich phase increased from 0.58 to 1 as we increased DEX composition within the two-phase region. We hypothesized that the chemical affinity between DEX and the bacteria cell wall acts to weakly confine the bacteria within the DEX-rich phase; however, motility can generate sufficient mechanical forces to overcome the soft confinement and propel the bacteria into the PEG-rich phase. Using optical tweezers to drag a bacterium across the DEX/PEG interface, we demonstrate that the overall bacteria partitioning is determined by a competition between the interfacial forces and bacterial propulsive forces. Our measurements are supported by a theoretical model of dilute active rods embedded within a periodic soft confinement potential. |
| title | Motility Modulates the Partitioning of Bacteria in Aqueous Two-Phase Systems |
| topic | Soft Condensed Matter |
| url | https://arxiv.org/abs/2405.08995 |