Amino Acid Starvation Slows Planktonic E. coli Growth but Does Not Slow Sessile Growth

Biofilms are aggregations of microorganisms that form on a solid surface, generally in a wet environment. Biofilms wreak havoc in their clinical manifestations, causing infections to the urinary, reproductive, and pulmonary systems. Although planktonic cell growth is well-understood in Escherichia coli, there is much less knowledge about how biofilms form and what sorts of environments foster biofilm formation. E. coli is responsible for a multitude of infections, including over 80% of urinary tract infections, making it an important model organism for biofilm formation. This project was designed to analyze how amino acid starvation impacts E. coli sessile growth and biofilm formation. The project demonstrated that, while amino acid starvation significantly slows planktonic, or free-swimming, growth, it does not slow sessile, or attached, growth. This demonstrates a clear discrepancy between when planktonic growth is triggered and when sessile growth is triggered, indicating that the physiological processes triggering each type of growth differ. The project has demonstrated that the evolutionary reasons behind biofilm attachment and sessile growth are poorly understood, and that a more comprehensive understanding of these processes will lead to a better understanding of why biofilm-associated infections are so common and so harmful.