The importance of bacterial growth phase for in planta virulence and pathogenicity testing: coordinated stress response regulation in fluorescent pseudomonads?

Abstract

Phytopathogenic strains of Pseudomonas syringae have different physiological properties in their different growth phases. Screening of four strains at the cellular level revealed that the sensitivity of P. syringae to oxidative stress, heat, and selected antibiotics is correlated with the growth phase and enzyme properties and is affected by the composition of the nutrient environment. The interrelation of responses to different stresses allows the conclusion to be made that coordinated stress response regulation occurs in some strains of P. syringae. This is important for studies that involve plant–bacteria associations in which the microbes have to cope with complex stress situations. It further opens an avenue of screening at the molecular level for stress response regulons in fluorescent pseudomonads.Key words: Pseudomonas syringae, antibiotics, catalase, growth phase, stress.