Single cell measurements of E.coli osmoregulation

The project will focus on the bacterial osmoregulatory network, crucial for cell survival; by utilizing truly interdisciplinary approaches to study the nature of living organisms.

The bacterial osmoregulatory network allows bacterial cells to maintain and adjust the concentration difference across the cellular membrane in response to frequent, often sudden changes in the external osmolarity. For example, soil bacteria are exposed to droughts and floods, bacteria that inhabit the human oral cavity experience concentration changes with food and fluid intake, and those that inhabit the human gut or infect the urinary tract experience concentration changes that reflect host metabolic processes. Research in bacterial osmoregulation has been extensive, and has predominantly utilized in vivo, bulk measurements and genetic manipulations to identify components of the network and demonstrate that the ability to sense and respond to changes in the external concentration is a key adaptation mechanism. However, many fundamental questions remain unanswered: for instance, how is a change in external concentration sensed, when does the recovery begin, when does it end, and how are the recovered cells different from those that have not experienced an osmotic challenge. The answers have thus far simply not been experimentally accessible.

I have recently developed cutting-edge methodologies for single cell, in vivo studies of the osmoregulatory network, demonstrating that capturing previously inaccessible experimental data and addressing many of the unanswered questions is possible (1). The student will apply these techniques, gaining expertise in molecular and microbiology methodologies as well as state-of-the-art fluorescence imaging techniques, microfluidic devices and optical trapping techniques. The project will include utilizing the developed system to determine the exact contributions of different components of the osmoregulatory network, and to establish the conditions under which they are used by the bacterial cell and the time scales on which they operate. Obtained data will be integrated in a simple mathematical model. Such predictive understanding of the osmoregulatory network stands in a direct relationship to our ability to construct artificial cells capable of functioning and sustaining useful properties in changing environments, as well as designing new pharmaceuticals to combat infectious disease affecting humans and animals alike.