Browsing by Author "Unelius, C. Rikard"

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    Chrysanthemyl 2-acetoxy-3-methylbutanoate: the sex pheromone of the citrophilous mealybug, Pseudococcus calceolariae
    (PERGAMON-ELSEVIER SCIENCE LTD, 2010) El Sayed, Ashraf M.; Unelius, C. Rikard; Twidle, Andrew; Mitchell, Vanessa; Manning, Lee Anne; Cole, Lyn; Suckling, David M.; Fernanda Flores, M.; Zaviezo, Tania; Bergmann, Jan
    Headspace volatiles collected from virgin females of the citrophilous mealybug, Pseudococcus calceolariae, contain three Compounds not present in the headspace of control samples. The main female-specific compound is identified as[2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropyl]methyl 2-acetoxy-3-methylbutanoate (chrysanthemyl 2-acetoxy-3-methylbutanoate). The other two compounds are identified as [2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropyl]methanol (chrysanthemol) and [2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropyl]methyl 2-hydroxy-3-methylbutanoate (chrysanthemyl 2-hydroxy-3-methylbutanoate). Traps baited with 100 mu g and 1000 mu g of chrysanthemyl 2-acetoxy-3-methylbutanoate captured 4- and 20-fold more males than traps baited with virgin females. (C) 2009 Elsevier Ltd. All rights reserved.
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    Diffusible signal factor signaling controls bioleaching activity and niche protection in the acidophilic, mineral-oxidizing leptospirilli
    (2021) Bellenberg, Soren; Salas, Beatriz; Ganji, Suresh; Jorquera-Roman, Cristian; Valenzuela, Maria Luisa; Buetti-Dinh, Antoine; Unelius, C. Rikard; Dopson, Mark; Vera, Mario
    Bioleaching of metal sulfide ores involves acidophilic microbes that catalyze the chemical dissolution of the metal sulfide bond that is enhanced by attached and planktonic cell mediated oxidation of iron(II)-ions and inorganic sulfur compounds. Leptospirillum spp. often predominate in sulfide mineral-containing environments, including bioheaps for copper recovery from chalcopyrite, as they are effective primary mineral colonizers and oxidize iron(II)-ions efficiently. In this study, we demonstrated a functional diffusible signal factor interspecies quorum sensing signaling mechanism in Leptospirillum ferriphilum and Leptospirillum ferrooxidans that produces (Z)-11-methyl-2-dodecenoic acid when grown with pyrite as energy source. In addition, pure diffusible signal factor and extracts from supernatants of pyrite grown Leptospirillum spp. inhibited biological iron oxidation in various species, and that pyrite grown Leptospirillum cells were less affected than iron grown cells to self inhibition. Finally, transcriptional analyses for the inhibition of iron-grown L. ferriphilum cells due to diffusible signal factor was compared with the response to exposure of cells to N- acyl-homoserine-lactone type quorum sensing signal compounds. The data suggested that Leptospirillum spp. diffusible signal factor production is a strategy for niche protection and defense against other microbes and it is proposed that this may be exploited to inhibit unwanted acidophile species.