Regulation of the flagellar motor in Bacillus subtilis

Bacteria exhibit many multicellular, complex behaviors such as motility and biofilm formation. Many motile bacteria in the environment exist as single cells that are propelled by rotating flagella and can also differentiate into aggregates that form a biofilm. Upon biofilm formation, cells transition and become non-motile while synthesizing an extracellular matrix. Here I used the model bacterial system Bacillus subtilis to study the transition from motile to non-motile cells in a biofilm. Using genetic, biochemistry, and cytology techniques, I was able to determine the mechanism of how a single, unique protein expressed by cells during biofilm formation is bifunctional and acts to inhibit motility as well as synthesize the extracellular matrix. I further explored the dynamics of flagellar assembly, number, function, and patterning and found the clutch protein localized to flagella, indicating the clutch protein directly acts at the flagellum to inhibit motility. The finding that a single protein inhibits motility during biofilm formation is informative for other bacterial systems. Understanding the transition between motile and non-motile cells is important to understanding biofilm formation and eradication. Once bacteria form a biofilm, it is extremely difficult to disrupt and therefore my findings have far reaching implications in not only bacterial function but also medicine and industry.