Biology Seminar - Thomas Bernhardt

Most bacteria surround themselves with multiple surface layers that are collectively referred to as the cell envelope. The peptidoglycan cell wall has long been thought to be the main stress-bearing layer of the envelope responsible for maintaining cell shape and integrity. However, recent results have also implicated the outer membrane of Gram-negative bacteria in the mechanical stability of the cell envelope. I will present our results demonstrating that the outer membrane plays a role in rod shape determination in addition to its barrier and envelope stabilizing functions. I will also present our studies of phage-induced cell lysis suggesting that membrane-anchored glycans play a conserved role in maintaining cell integrity in Gram-positive bacteria. Overall, our results indicate that the mechanical properties of the bacterial cell envelope needed to prevent osmotic lysis are contributed by several different surface layers in addition to the peptidoglycan cell wall.