title: Imaging mass spectrometry of a coral microbe interaction with fungi.
abstract: Fungal infections are increasing worldwide, including in the aquatic environment. Microbiota that coexist with marine life can provide protection against fungal infections by secretion of metabolites with antifungal properties. Our laboratory has developed mass spectrometric methodologies with the goal of improving our functional understanding of microbial metabolites and guiding the discovery process of anti-infective agents from natural sources. GA40, a Bacillus amyloliquefaciens strain isolated from an octocoral in Panama, displayed antifungal activity against various terrestrial and marine fungal strains. Using matrix-assisted laser desorption/ionization-imaging mass spectrometry (MALDI-IMS), the molecular species produced by this microbe were visualized in a side-by-side interaction with two representative fungal strains, Aspergillus fumigatus and Aspergillus niger. The visualization was performed directly on the agar without the need for extraction. By evaluating the spatial distributions, relative intensities and m/z values of GA40 secreted metabolites in the fungal interactions and singly grown control colonies, we obtained insight into the antifungal activity of secreted metabolites. Annotation of GA40 metabolites observed in MALDI-IMS was facilitated by MS/MS networking analysis, a mass spectrometric technique that clusters metabolites with similar MS/MS fragmentation patterns. This analysis established that the predominant GA40 metabolites belong to the iturin family. In a fungal inhibition assay of A. fumigatus, the GA40 iturin metabolites were found to be responsible for the antifungal properties of this Bacillus strain.
authors.affiliation: Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California at San Diego, La Jolla, California, USA.
authors.forename: Wilna J
authors.initials: WJ
authors.lastname: Moree
authors.affiliation: Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California at San Diego, La Jolla, California, USA.|Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, California, USA.
authors.forename: Jane Y
authors.initials: JY
authors.lastname: Yang
authors.affiliation: Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, California, USA.
authors.forename: Xiling
authors.initials: X
authors.lastname: Zhao
authors.affiliation: Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California at San Diego, La Jolla, California, USA.|Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, California, USA.
authors.forename: Wei-Ting
authors.initials: WT
authors.lastname: Liu
authors.affiliation: Instituto de Investigaciones Científicas y Servicios de Alta Tecnología, Ciudad del Saber, Clayton, 0843-01103 Panamá.
authors.forename: Marystella
authors.initials: M
authors.lastname: Aparicio
authors.affiliation: Instituto de Investigaciones Científicas y Servicios de Alta Tecnología, Ciudad del Saber, Clayton, 0843-01103 Panamá.
authors.forename: Librada
authors.initials: L
authors.lastname: Atencio
authors.affiliation: Instituto de Investigaciones Científicas y Servicios de Alta Tecnología, Ciudad del Saber, Clayton, 0843-01103 Panamá.
authors.forename: Javier
authors.initials: J
authors.lastname: Ballesteros
authors.affiliation: Instituto de Investigaciones Científicas y Servicios de Alta Tecnología, Ciudad del Saber, Clayton, 0843-01103 Panamá.
authors.forename: Joel
authors.initials: J
authors.lastname: Sánchez
authors.affiliation: Instituto de Investigaciones Científicas y Servicios de Alta Tecnología, Ciudad del Saber, Clayton, 0843-01103 Panamá.
authors.forename: Ronnie G
authors.initials: RG
authors.lastname: Gavilán
authors.affiliation: Instituto de Investigaciones Científicas y Servicios de Alta Tecnología, Ciudad del Saber, Clayton, 0843-01103 Panamá.
authors.forename: Marcelino
authors.initials: M
authors.lastname: Gutiérrez
authors.affiliation: Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California at San Diego, La Jolla, California, USA.|Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, California, USA.
authors.forename: Pieter C
authors.initials: PC
authors.lastname: Dorrestein
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000382:microbiology*; D000935:Antifungal Agents / Q000032:analysis*; D001232:Aspergillus fumigatus / Q000502:physiology*; D001234:Aspergillus niger / Q000502:physiology*; D001407:Bacillus / Q000737:chemistry / Q000502:physiology*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013559:Symbiosis
chemical_list: D000935:Antifungal Agents