title: Pseudomonas aeruginosa inhibits the growth of Cryptococcus species.
abstract: Pseudomonas aeruginosa is a ubiquitous and opportunistic bacterium that inhibits the growth of different microorganisms, including Gram-positive bacteria and fungi such as Candida spp. and Aspergillus fumigatus. In this study, we investigated the interaction between P. aeruginosa and Cryptococcus spp. We found that P. aeruginosa PA14 and, to a lesser extent, PAO1 significantly inhibited the growth of Cryptococcus spp. The inhibition of growth was observed on solid medium by the visualization of a zone of inhibition of yeast growth and in liquid culture by viable cell counting. Interestingly, such inhibition was only observed when P. aeruginosa and Cryptococcus were co-cultured. Minimal inhibition was observed when cell-cell contact was prevented using a separation membrane, suggesting that cell contact is required for inhibition. Using mutant strains of Pseudomonas quinoline signaling, we showed that P. aeruginosa inhibited the growth of Cryptococcus spp. by producing antifungal molecules pyocyanin, a redox-active phenazine, and 2-heptyl-3,4-dihydroxyquinoline (PQS), an extracellular quorum-sensing signal. Because both P. aeruginosa and Cryptococcus neoformans are commonly found in lung infections of immunocompromised patients, this study may have important implication for the interaction of these microbes in both an ecological and a clinical point of view.
authors.affiliation: Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA.
authors.forename: Antonella
authors.initials: A
authors.lastname: Rella
authors.forename: Mo Wei
authors.initials: MW
authors.lastname: Yang
authors.forename: Jordon
authors.initials: J
authors.lastname: Gruber
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Montagna
authors.forename: Chiara
authors.initials: C
authors.lastname: Luberto
authors.forename: Yong-Mei
authors.initials: YM
authors.lastname: Zhang
authors.forename: Maurizio
authors.initials: M
authors.lastname: Del Poeta
mesh_terms: D000898:Antibiosis; D001422:Bacterial Adhesion; D003454:Cryptococcus / Q000254:growth & development*; D003470:Culture Media / Q000737:chemistry; D009172:Mycology / Q000379:methods; D010619:Phenazines / Q000378:metabolism / Q000633:toxicity; D011550:Pseudomonas aeruginosa / Q000378:metabolism / Q000502:physiology*; D011710:Pyocyanine / Q000378:metabolism / Q000633:toxicity; D011804:Quinolines / Q000378:metabolism / Q000633:toxicity
chemical_list: D003470:Culture Media; D010619:Phenazines; D011804:Quinolines; D011710:Pyocyanine; C037219:quinoline
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