Carbon source and surface type influence the early-stage biofilm formation by rhizosphere bacterium Pseudomonas donghuensis P482.

The competence of bacteria to colonize different environmental niches is often determined by their ability to form biofilms. This depends on both cellular and extracellular factors, such as individual characteristics of a strain, type of colonized surface (abiotic or biotic) or availability and source of nutrients. Pseudomonas donghuensis P482 efficiently colonizes rhizosphere of various plant hosts, but a connection between plant tissue colonization and biofilm formation has not been verified for P482 up to date. Here we demonstrate that the ability of P482 to form biofilm on abiotic surfaces and the structural characteristics of the biofilm are connected to the type of carbon source available to the bacteria, with glycerol promoting formation of developed biofilm at early stages. Also, the type of substratum, polystyrene or glass, significantly influences the ability of P482 to attach to the surface, possibly due to hydrophobic effects. Moreover, mutants in genes associated with motility or chemotaxis, synthesis of polysaccharides, and encoding proteases or regulatory factors, affected in biofilm formation on glass were fully capable of colonizing root tissue of both tomato and maize hosts. This indicates that the ability to form biofilm on distinct abiotic surfaces does not simply correlate with the efficient colonization of rhizosphere and formation of biofilm on plant tissue by P482.