College of Science

SEMINAR: Structure and dynamics of bacterial collectives, Dr. Albert Siryaporn [UC Irvine]

SEMINAR: Structure and dynamics of bacterial collectives, Dr. Albert Siryaporn [UC Irvine]

Nov 20, 2019 11:00 PM to Nov 21, 2019 12:00 PM at

Physics and Astronomy Seminar

November 21, 2019, 11:00 am to 12:00 pm at Building 8, Room 241

 

 

Dr. Albert Siryaporn (UC Irvine)

 

Structure and dynamics of bacterial collectives


The physical interactions between bacteria and the environment give rise to organized structures and collective behaviors. In environments that contain networks of moving fluids such as blood vasculature and in plants, bacteria form biofilm structures composed of dense communities. The physical mechanisms that determine the spatial organization of bacteria in flow are not understood. We show that the bacterium P. aeruginosa colonizes flow networks using a cyclical process that we have termed dynamic switching, which distributes bacterial sub-populations upstream and downstream in flow through two phases: movement on surfaces and via the bulk. We measure electron flow in cells in both phases using fluorescence lifetime imaging microscopy (FLIM), which reports the activity of the electron carrier nicotinamide adenine dinucleotide (NADH) in live cells. We find that cells in the bulk and on surfaces exhibit distinct electron carrier profiles, with surface-attached cells exhibiting FLIM lifetimes that are associated with higher levels of free NADH. Our results demonstrate the use of FLIM to non-invasively measure NADH dynamics in early biofilms and suggest a model in which a metabolic rearrangement accompanies dynamic switching. Our results show that dynamic switching enables bacteria to explore flow networks efficiently, which maximizes dispersal and colonization, establishes the organizational structure of early biofilms, and impacts metabolic activity.

 

 

10:50 am Refreshments

 

11:00 am Seminar