Squamocin mode of action to stimulate biofilm formation of Pseudomonas plecoglossicida J26, a PAHs degrading bacterium

Abstract: Squamocin, an annonaceous acetogenin (ACG) extracted from Annona cherimolia (Annonaceae), has been shown to increase biofilm production of Pseudomonas plecoglossicida J26 (closely related to P. plecoglossicida), a polycyclic aromatic hydrocarbon degrading bacterium. PAHs have become priority pollutants for bioremediation due to their carcinogenicity and toxicity. The effect of various stressful stimuli (naphthalene, octanol, HCl, and NaCl) on cell growth, biofilm formation and autoinducer production of P. plecoglossicida were evaluated and compared with the effect of squamocin to establish its mode of action on biofilm formation. All stressors that inhibited growth stimulated autoinducer production while squamocin was growth stimulant at concentrations above 2.5 μg ml−1. Despite structural similarities, squamocin is not an autoinducer agonist. It indirectly stimulates autoinducer production and increases P. plecoglossicida J26 cell growth. This is the first report on an ACG mode of action in the formation of biofilm in a naphthalene-degrading strain. [Copyright &y& Elsevier]