G ram‐negative bacteria can also form pellicles

Summary There is a growing interest in the bacterial pellicle, a biofilm floating at the air–liquid interface. Pellicles have been well studied in the G ram‐positive bacterium B acillus subtilis, but far less in G ram‐negative bacteria, where pellicle studies have mostly focused on matrix components rather than on the regulatory cascades involved. Several G ram‐negative bacteria, including pathogenic bacteria, have been shown to be able to form a pellicle under static conditions. Here, we summarize the growing body of knowledge about pellicle formation in G ram‐negative bacteria, especially about the components of the pellicle matrix. We also propose that the pellicle is a specific biofilm, and that its formation involves particular processes. Since this lifestyle concerns a growing number of bacteria, its properties undoubtedly deserve further investigation.