The bacterial cell envelope is one of the best targets in antimicrobial development. This proposal focuses on understanding how lipids move between the membranes of the gram-negative cell envelope as understanding this pathway could lead to inhibiting it and thus the development of new antimicrobials. This proposal focuses on understanding how lipids move between the membranes of the gram-negative cell envelope. Until recently how lipids were transported between the membranes of the cell envelope was unknown, however, the Mla pathway, has been identified that provides the first evidence of a lipid transport pathway. How this pathway functions remains unknown. The aim of this proposal is to tackle these issues. Neutron reflectometry provides the ideal tool for monitoring the movement of lipids to and from the membrane and provide vital information about how the Mla pathway function.