Bacterial proliferation affects us from our personal microbiomes to the food industry. While bacteria come in many shapes, the ancestral shape of the bacteria appears to be rod-like. There are several groups of bacteria, including several important pathogens, that have become more or less spherical. We are directly studying the evolutionary transition from rod-like to spherical cell shape in order to learn more about how and why this transition occurs.
A single gene appears to be responsible for determining rod-like shape in bacteria. In the the major model organisms the deletiion of this gene kills the cells in short order, making investigation difficult. However, our bacterium that tolerates the deletion that renders it spherical. These cells are sick (take twice as long to divide). This provides an opportunity to take an experimental evolution approach. Evolved spherical cells can be studied in order to learn what genetic changes lead to spherical cell shape.