title: Parasitic growth of Pseudomonas aeruginosa in co-culture with the chitinolytic bacterium Aeromonas hydrophila.
abstract: Polymer-degrading bacteria face exploitation by opportunistic bacteria that grow with the degradation products without investing energy into production of extracellular hydrolytic enzymes. This scenario was investigated with a co-culture of Aeromonas hydrophila and Pseudomonas aeruginosa with chitin as carbon, nitrogen and energy source. In single cultures, A. hydrophila could grow with chitin, while P. aeruginosa could not. Co-cultures with both strains had a biphasic course. In the first phase, P. aeruginosa grew along with A. hydrophila without affecting it. The second phase was initiated by a rapid inactivation of and a massive acetate release by A. hydrophila. Both processes coincided and were dependent on quorum sensing-regulated production of secondary metabolites by P. aeruginosa. Among these the redox-active phenazine compound pyocyanin caused the release of acetate by A. hydrophila by blocking the citric acid cycle through inhibition of aconitase. Thus, A. hydrophila was forced into an incomplete oxidation of chitin with acetate as end-product, which supported substantial growth of P. aeruginosa in the second phase of the co-culture. In conclusion, P. aeruginosa could profit from a substrate that was originally not bioavailable to it by influencing the metabolism and viability of A. hydrophila in a parasitic way.
authors.affiliation: Universität Konstanz, Fachbereich Biologie, Mikrobielle Okologie, Fach M654, 78457 Konstanz, Germany.
authors.forename: Nina
authors.initials: N
authors.lastname: Jagmann
authors.forename: Hans-Philipp
authors.initials: HP
authors.lastname: Brachvogel
authors.forename: Bodo
authors.initials: B
authors.lastname: Philipp
mesh_terms: D000085:Acetates / Q000378:metabolism; D000154:Aconitate Hydratase / Q000378:metabolism; D016980:Aeromonas hydrophila / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D002686:Chitin / Q000737:chemistry / Q000378:metabolism*; D018920:Coculture Techniques; D006790:Host-Parasite Interactions; D010619:Phenazines / Q000378:metabolism; D011552:Pseudomonas Infections / Q000378:metabolism; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity; D011710:Pyocyanine / Q000378:metabolism; D015363:Quinolones / Q000378:metabolism
chemical_list: D000085:Acetates; D010619:Phenazines; D015363:Quinolones; D002686:Chitin; D011710:Pyocyanine; D000154:Aconitate Hydratase