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

In Pseudomonas 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 Pseudomonas 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 Pseudomonas putida and introduces a potential strategy for controlling biofilm formation.