Distinct microcolony morphologies promote flow-dependent bacterial colonization

Abstract

Fluid flows can impact bacterial behaviors in unexpected ways (1-3). The high shear rate in heart valves should reduce colonization, but in endocarditis, valves are often counter-intuitively colonized by Staphylococcus aureus and Enterococcus faecalis (4, 5). Here we discover bacteria-specific mechanisms for preferential surface colonization in higher shear rate environments. This behavior enables bacteria that are outcompeted in low flow to dominate in high flow. Flow-dependent colonization by S. aureus and E. faecalis are mediated by distinct mechanisms that depend on each species microcolony morphologies: transport of a dispersal signaling molecule for clustered S. aureus and mechanical forces for linear chains of E. faecalis. These results suggest that microcolony morphologies have previously unappreciated costs and benefits in different environments, like those introduced by flow. One-Sentence SummaryBacterial surface colonization in high fluid flow depends upon the species clustered or chained microcolony morphologies.