title: Inhibition of fungal colonization by Pseudoalteromonas tunicata provides a competitive advantage during surface colonization.
abstract: The marine epiphytic bacterium Pseudoalteromonas tunicata produces a range of extracellular secondary metabolites that inhibit an array of common fouling organisms, including fungi. In this study, we test the hypothesis that the ability to inhibit fungi provides P. tunicata with an advantage during colonization of a surface. Studies on a transposon-generated antifungal-deficient mutant of P. tunicata, FM3, indicated that a long-chain fatty acid-coenzyme A ligase is involved in the production of a broad-range antifungal compound by P. tunicata. Flow cell experiments demonstrated that production of an antifungal compound provided P. tunicata with a competitive advantage against a marine yeast isolate during surface colonization. This compound enabled P. tunicata to disrupt an already established fungal biofilm by decreasing the number of yeast cells attached to the surface by 66% +/- 9%. For in vivo experiments, the wild-type and FM3 strains of P. tunicata were used to inoculate the surface of the green alga Ulva australis. Double-gradient denaturing gradient gel electrophoresis analysis revealed that after 48 h, the wild-type P. tunicata had outcompeted the surface-associated fungal community, whereas the antifungal-deficient mutant had no effect on the fungal community. Our data suggest that P. tunicata is an effective competitor against fungal surface communities in the marine environment.
authors.affiliation: School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney 2052, New South Wales, Australia.
authors.forename: A
authors.initials: A
authors.lastname: Franks
authors.forename: S
authors.initials: S
authors.lastname: Egan
authors.forename: C
authors.initials: C
authors.lastname: Holmström
authors.forename: S
authors.initials: S
authors.lastname: James
authors.forename: H
authors.initials: H
authors.lastname: Lappin-Scott
authors.forename: S
authors.initials: S
authors.lastname: Kjelleberg
mesh_terms: D000935:Antifungal Agents / Q000378:metabolism; D001483:Base Sequence; D018441:Biofilms / Q000254:growth & development; D002448:Cell Adhesion; D003066:Coenzyme A Ligases / Q000235:genetics / Q000378:metabolism; D004271:DNA, Fungal / Q000235:genetics; D017753:Ecosystem; D005658:Fungi / Q000235:genetics / Q000254:growth & development* / Q000502:physiology; D005838:Genotype; D008386:Marine Biology; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D031161:Pseudoalteromonas / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D013499:Surface Properties; D044445:Ulva / Q000254:growth & development / Q000382:microbiology; D000098859:Long-Chain-Fatty-Acid-CoA Ligase
chemical_list: D000935:Antifungal Agents; D004271:DNA, Fungal; D003066:Coenzyme A Ligases; D000098859:Long-Chain-Fatty-Acid-CoA Ligase