Antibiotic activity altered by competitive interactions between two coral reef – associated bacteria

Microbes produce natural products that mediate interactions with each other and with their environments, representing a potential source of antibiotics for human use. The biosynthesis of some antibiotics whose constitutive production otherwise remains low has been shown to be induced by competing microbes. Competition among macroorganism hosts may further influence the metabolic outputs of members of their microbiomes, especially near host surfaces where hosts and microbial symbionts come into close contact. At multiple field sites in Fiji, we collected matched samples of corals and algae that were freestanding or in physical contact with each other, cultivated bacteria from their surfaces, and explored growth-inhibitory activities of these bacteria against marine and human pathogens. In the course of the investigation, an interaction was discovered between two coral-associated actinomycetes in which an Agrococcus sp. interfered with the antibiotic output of a Streptomyces sp. Several diketopiperazines identified from the antibiotic-producing bacterium could not, on their own, account for the antibiotic activity indicating that other, as yet unidentified molecule(s) or molecular blends, possibly including diketopiperazines, are likely involved. This observation highlights the complex molecular dynamics at play among microbiome constituents. The mechanisms through which microbial interactions impact the biological activities of specialized metabolites deserve further attention considering the ecological and commercial importance of bacterial natural products

Sharing and community curation of mass spectrometry data with Global Natural Products Social Molecular Networking

The potential of the diverse chemistries present in natural products (NP) for biotechnology and medicine remains untapped because NP databases are not searchable with raw data and the NP community has no way to share data other than in published papers. Although mass spectrometry techniques are well-suited to high-throughput characterization of natural products, there is a pressing need for an infrastructure to enable sharing and curation of data. We present Global Natural Products Social molecular networking (GNPS, http://gnps.ucsd.edu), an open-access knowledge base for community wide organization and sharing of raw, processed or identified tandem mass (MS/MS) spectrometry data. In GNPS crowdsourced curation of freely available community-wide reference MS libraries will underpin improved annotations. Data-driven social-networking should facilitate identification of spectra and foster collaborations. We also introduce the concept of ‘living data’ through continuous reanalysis of deposited data

Mechanism of Action of the Cyanobacterial Marine Natural Product Honaucin A

The bioactive natural products of cyanobacteria show great therapeutic promise in the treatment of a number of ailments. Advancement of these compounds into clinical settings is greatly facilitated by knowledge of the molecules' cellular target and mechanism of action. This thesis presents the multidisciplinary examination of the bioactivity and mechanism of action of the cyanobacterial marine natural product honaucin A. Preliminary evidence for the anti-inflammatory activity of honaucin A was observed in in vitro assays. Evaluation of analogues of honaucin A revealed that certain structural features were necessary for this bioactivity. The marine natural product was subsequently shown to exhibit in vivo activity in the Mouse Ear Edema Model. RNA sequencing of was utilized as a method of understanding differences in gene expression of cultured macrophages that result from honaucin A treatment. This analysis led us to hypothesize that honaucin A exerts its bioactivity through activation of the cytoprotective Nrf2 (nuclear erythroid 2-related factor 2)-ARE/EpRE (antioxidant response element/ electrophile response element) signaling pathway. Activation of this pathway by honaucin A in cultured human cells was confirmed using an Nrf2 luciferase reporter assay. In vitro alkylation experiments with the natural product and N-acetyl-L-cysteine suggested that honaucin A may have the ability to activate this pathway through covalent interaction with the sulfhydryl residues of the repressor protein Keap1. Screening of a library of marine natural products uncovered eight compounds in addition to honaucin A that activate Nrf2-ARE/EpRE. These molecules, isolated from cyanobacteria and an alga, bear structural similarities to honaucin A. This panel of Nrf2-ARE activators may have applications in the treatment of disorders with inflammatory components including neurodegeneration, cadiovascular diseases, cancer, and obesit

Direct detection of fungal siderophores on bats with white-nose syndrome via fluorescence microscopy-guided ambient ionization mass spectrometry.

White-nose syndrome (WNS) caused by the pathogenic fungus Pseudogymnoascus destructans is decimating the populations of several hibernating North American bat species. Little is known about the molecular interplay between pathogen and host in this disease. Fluorescence microscopy ambient ionization mass spectrometry was used to generate metabolic profiles from the wings of both healthy and diseased bats of the genus Myotis. Fungal siderophores, molecules that scavenge iron from the environment, were detected on the wings of bats with WNS, but not on healthy bats. This work is among the first examples in which microbial molecules are directly detected from an infected host and highlights the ability of atmospheric ionization methodologies to provide direct molecular insight into infection

Direct Detection of Fungal Siderophores on Bats with White-Nose Syndrome via Fluorescence Microscopy-Guided Ambient Ionization Mass Spectrometry

White-nose syndrome (WNS) caused by the pathogenic fungus Pseudogymnoascus destructans is decimating the populations of several hibernating North American bat species. Little is known about the molecular interplay between pathogen and host in this disease. Fluorescence microscopy ambient ionization mass spectrometry was used to generate metabolic profiles from the wings of both healthy and diseased bats of the genus Myotis. Fungal siderophores, molecules that scavenge iron from the environment, were detected on the wings of bats with WNS, but not on healthy bats. This work is among the first examples in which microbial molecules are directly detected from an infected host and highlights the ability of atmospheric ionization methodologies to provide direct molecular insight into infection

Direct Detection of Fungal Siderophores on Bats with White-Nose Syndrome via Fluorescence Microscopy-Guided Ambient Ionization Mass Spectrometry

White-nose syndrome (WNS) caused by the pathogenic fungus Pseudogymnoascus destructans is decimating the populations of several hibernating North American bat species. Little is known about the molecular interplay between pathogen and host in this disease. Fluorescence microscopy ambient ionization mass spectrometry was used to generate metabolic profiles from the wings of both healthy and diseased bats of the genus Myotis. Fungal siderophores, molecules that scavenge iron from the environment, were detected on the wings of bats with WNS, but not on healthy bats. This work is among the first examples in which microbial molecules are directly detected from an infected host and highlights the ability of atmospheric ionization methodologies to provide direct molecular insight into infection