20 research outputs found

    Insect‐associated bacteria assemble the antifungal butenolide gladiofungin by non‐canonical polyketide chain termination

    Get PDF
    Genome mining of one of the protective symbionts ( Burkholderia gladioli ) of the invasive beetle Lagria villosa revealed a cryptic gene cluster that codes for the biosynthesis of a novel antifungal polyketide with a glutarimide pharmacophore. Targeted gene inactivation, metabolic profiling, and bioassays led to the discovery of the gladiofungins as previously‐overlooked components of the antimicrobial armory of the beetle symbiont, which are highly active against the entomopathogenic fungus Purpureocillium lilacinum . By mutational analyses, isotope labeling, and computational analyses of the modular polyketide synthase, we found that the rare butenolide moiety of gladiofungins derives from an unprecedented polyketide chain termination reaction involving a glycerol‐derived C3 building block. The key role of an A‐factor synthase (AfsA)‐like offloading domain was corroborated by CRISPR‐Cas‐mediated gene editing, which facilitated precise excision within a PKS domain

    Multimodal Molecular Imaging and Identification of Bacterial Toxins Causing Mushroom Soft Rot and Cavity Disease

    Get PDF
    Soft rot disease of edible mushrooms leads to rapid degeneration of fungal tissue and thus severely affects farming productivity worldwide. The bacterial mushroom pathogen Burkholderia gladioli pv. agaricicola has been identified as the cause. Yet, little is known about the molecular basis of the infection, the spatial distribution and the biological role of antifungal agents and toxins involved in this infectious disease. We combine genome mining, metabolic profiling, MALDI-Imaging and UV Raman spectroscopy, to detect, identify and visualize a complex of chemical mediators and toxins produced by the pathogen during the infection process, including toxoflavin, caryoynencin, and sinapigladioside. Furthermore, targeted gene knockouts and in vitro assays link antifungal agents to prevalent symptoms of soft rot, mushroom browning, and impaired mycelium growth. Comparisons of related pathogenic, mutualistic and environmental Burkholderia spp. indicate that the arsenal of antifungal agents may have paved the way for ancestral bacteria to colonize niches where frequent, antagonistic interactions with fungi occur. Our findings not only demonstrate the power of label-free, in vivo detection of polyyne virulence factors by Raman imaging, but may also inspire new approaches to disease control. © 2021 The Authors. ChemBioChem published by Wiley-VCH Gmb

    Space as a Tool for Astrobiology: Review and Recommendations for Experimentations in Earth Orbit and Beyond

    Get PDF

    Effect of Crystal Size on Framework Defects and Water Uptake in Fluoride Mediated Silicalite‑1

    No full text
    The relationship between framework defects and crystal size in fluoride mediated silicalite-1 was investigated through nitrogen physisorption, X-ray diffraction, and vapor adsorption of ethanol and water on samples with crystal sizes ranging from 0.4 to 30 ÎŒm in the <i>b</i> direction of the silicalite-1 crystals. X-ray diffraction reveals a shift in the lattice system from a predominantly monoclinic phase in smaller crystals to an orthorhombic phase in the larger crystals. <sup>29</sup>Si MAS studies reveal minimal differences in framework silanol defect concentration. An H-4 type hysteresis in 77 K N<sub>2</sub> adsorption isotherm and BdB-FHH pore size analysis reveal the presence of slit-like pores and a larger average pore size as well as a larger volume fraction of “microfissures” in the larger crystals. Pure vapor adsorption measurements show more than a 2-fold increase in water uptake from 0.21 mmol/g to 0.51 mmol/g from the smallest to largest samples at 308 K near unit activity, while ethanol uptake remains on the order of 2.4 mmol/g for all samples. An increase in desorption hysteresis with crystal size and negligible differences in isosteric heats of adsorption of water lend support to the presence of microfissure defects in the larger samples. IAST predications for binary adsorption of ethanol and water in the silicalite-1 samples reveal a 2-fold ethanol/water selectivity enhancement for dilute (<5 wt % EtOH) solutions when crystal size is reduced. This systematic study of N<sub>2</sub> physisorption, framework composition, and ethanol/water adsorption highlights the critical role that crystal size plays in the adsorption process, which can have significant implications for biofuel processes that produce dilute aqueous ethanol as a raw product
    corecore