Release of extracellular DNA by Pseudomonas sp. as a major determinant for biofilm switching and an early indicator for cell population control

In <i>Pseudomonas</i> sp., the switch from planktonic to sessile state is driven by extracellular DNA release. We observed a subpopulation of cells associated with eDNA in the planktonic phase, as indicated by propidium iodide staining. Surprisingly, the size of this subpopulation was directly correlated with the overall biofilm-forming capacity of the population. This challenges the prevailing understanding of phenotypic switching and confirms that biofilm formation in <i>Pseudomonas</i> is a collective process governed by eDNA release. Automated flow cytometry tracked the process, and PI-positive cells were identified as an early indicator of biofilm formation. Automated glucose pulsing successfully reduced biofilm formation by interfering with PI-positive cell proliferation. This study provides insights into the collective determinants of biofilm switching in <i>Pseudomonas putida</i> and introduces a potential strategy for controlling biofilm formation.