Illuminating the relationship between flagellar activity and bacterial swimming

Bacterial swimming and chemotaxis serves as a model system for understanding information processing in living organisms. My thesis project was focused on studying the swimming behavior of Escherchia coli bacterial cells. These cells swim by rotating helical filaments called flagella. An individual cell can have anywhere from 1 to 10 flagella. In a process called chemotaxis, cells modulate the rotational direction of their flagella to modify their swimming behavior and move towards more favorable environments. The primary goal of this thesis was to determine how the number of flagella on a cell affects its swimming behavior. I designed and constructed a unique instrument, combining optical tweezers and high-speed fluorescence imaging. This instrument allowed me to simultaneously measure the activity of the individual flagella on a cell, while also monitoring the swimming behavior of the cell. These results provided a large amount of data regarding the relationship between flagella number, CW bias and tumble bias. In particular, I discovered that the tumble bias of a swimming cell is robust against variations in flagellar number. Cells with 2 flagella and cells with as many as 8 flagella have the same average tumble bias. Many other results regarding this system are presented throughout this thesis. The goals and organization of the thesis are summarized in Chapter 1.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2014

Author dc:creator

• Mears, Patrick

Contributors dc:contributor

• Chemla, Yann R.
• Kuhlman, Thomas E.
• Dahmen, Karin A.
• Schulten, Klaus J.

• Escherichia coli
• biophysics
• optical tweezers
• chemotaxis
• fluoresence imaging
• systems biology

Statement dc:rights

• Copyright 2014 Patrick J. Mears

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/49486

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/49486