The model predator Acanthamoeba castellanii induces the production of 2,4, DAPG by the biocontrol strain Pseudomonas fluorescens Q2-87

Fluorescent pseudomonads show great potential as biological control agents due to their capability to produce antifungal toxins such as 2,4-diacetylphloroglucinol (DAPG). DAPG is synthesized from the precursor monoacetyl-phloroglucinol (MAPG) and its production depends on the metabolic state of the bacteria as well as on their interaction with other organisms. In this study we show that Pseudomonas fluorescens responds to the bacterivorous amoeba Acanthamoeba castellanii by upregulating the production of phloroglucinol derivates in a density-dependent manner. Living amoebae caused moreover a distortion of the MAPG to DAPG balance in favor of the latter, suggesting that amoebae may interfere with the first steps of DAPG synthesis. Predator–prey interactions appear thus to be an important factor for the regulation of antibiotics production in biocontrol microorganisms.