Involvement of bacterial migration in the development of complex multicellular structures in <i>Pseudomonas aeruginosa</i> biofilms

TLDR

Understanding how single cells evolve into complex biofilm structures is essential for developing strategies to control biofilm formation. The study investigates bacterial migration patterns during Pseudomonas aeruginosa biofilm development. Time‑lapse confocal laser scanning microscopy of colour‑coded wild‑type and motility‑mutant P. aeruginosa biofilms was employed to observe migration patterns.

Abstract

Detailed knowledge of the developmental process from single cells scattered on a surface to complex multicellular biofilm structures is essential in order to create strategies to control biofilm development. In order to study bacterial migration patterns during Pseudomonas aeruginosa biofilm development, we have performed an investigation with time-lapse confocal laser scanning microscopy of biofilms formed by various combinations of colour-coded P. aeruginosa wild type and motility mutants. We show that mushroom-shaped multicellular structures in P. aeruginosa biofilms can form in a sequential process involving a non-motile bacterial subpopulation and a migrating bacterial subpopulation. The non-motile bacteria form the mushroom stalks by growth in certain foci of the biofilm. The migrating bacteria form the mushroom caps by climbing the stalks and aggregating on the tops in a process which is driven by type-IV pili. These results lead to a new model for biofilm formation by P. aeruginosa.