We use a reactive transport modeling approach to evaluate the interactions between microorganisms mediated by signaling molecules (quorum sensing, QS). Using a nondimensionalized advection-diffusion-reaction equation, QS behavior of single and multiple microbial aggregates was investigated across a range of Péclet and Damköhler numbers. The results highlight the importance of the distance between microbial aggregates and their relative location to the flow direction. Also, QS activation triggering the production of more signaling molecules facilitates the cell-to-cell communication over long distances.