Membrane lipids form the structural basis of all cells. In bacteria Escherichia coli uses predominantly phospholipids in its cell envelope. However, beyond E. coli a range of lipids are found in bacterial membranes. In the marine environment, it is well established that phosphorus availability significantly affects lipid composition in the phytoplankton, whereby sulfur-containing lipids are used to substitute phospholipids. This remodelling offers a significant competitive advantage for these organisms, allowing them to adapt to oligotrophic environments. Until very recently, abundant marine heterotrophic bacteria were thought to lack the capacity for lipid remodelling in response to phosphorus deficiency. However, recent work by myself and others has now demonstrated that lipid remodelling occurs in many ecologically important marine heterotrophs, which are not only numerically abundant in marine waters but also crucial players in the biogeochemical cycling of key elements. However, the ecological and physiological consequences of lipid remodelling, in response to nutrient limitation, remain unknown.
The overall aim of this project is to use a synthesis of molecular biology, microbial physiology, and "omics" approaches to reveal the fitness trade-offs of lipid remodelling in marine heterotrophic bacteria, providing novel insights into the ecophysiology of lipid remodelling and its consequences for marine nutrient cycling. The project is further divided into three main work packages.
1) Obtaining a fundamental understanding of whole cell responses to lipid remodelling using comparative “omics” approaches.
2) Mechanistic insight into lipid remodelling and its impact on membrane composition and transporter activities.
3) lipid remodelling in marine heterotrophic bacteria and interaction with protists grazers and bacterial phages
