Chemotaxis enables marine bacteria to utilize microscale nutrient patches and many marine bacteria are excellent at chemotaxis, markedly outperforming the classic chemotaxis model organism E. coli. In naturally occurring bacterial communities, we have observed the dramatic, fast formation of ephemeral accumulations of bacteria by chemotaxis into the ‘phycosphere’, the microscale region surrounding individual phytoplankton cells. Using high-resolution video microscopy and cell tracking, we have for the first time precisely dissected the spatio-temporal dynamics of this process. We are using this unique data set as input for a mathematical model that ‘scales up’ these microscale dynamics to yield predictions of the relative contribution of motile and non-motile bacteria to the utilization of nutrients from the phycosphere. By merging direct observations with ecological modeling, these results will help us understand resource competition among diverse bacterial communities and the roles of phytoplankton-bacteria interactions in biogeochemical cycling.
Now working on this theme: Steven Smriga, Vicente Fernandez.