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Abstract:
Crude extracts of in vitro and in vivo cultures of two strains of Photorhabdus I. sonorensis (Enterobacteriaceae) were analyzed by TLC, HPLC-UV and LC-MS. Nine unique compounds with mass/charge ratios (m/z) ranging from 331.3 to 713.5 were found in MS analyses. Bioactivity of extracts was assessed on a selection of plant pathogens/pests and non-target species. Caborca strain extracts showed the highest activity against Helicoverpa zea (Lepidoptera: Noctuidae) neonates at all concentrations tested. Mortality ranged from 11% (at 10 mu g/ml) to 37% (at 40 mu g/ml). Strain CH35 extracts showed the highest nematicidal activity on Meloidogyne incognita (Tylenchida: Meloidogynidae) at 40 mu g/ml. Low to no nematicidal activity was observed against the non-target species Steinernema caipocapsae (Rhabditida: Steinernematidae) and Caenorhabditis elegans (Rhabditida: Rhabditidae). Caborca extracts exhibited a strong antibiotic effect on Pseudomonas syringae (Pseudomonadales: Pseudomonadacedae) at 40 mu g/ml, while both Caborca and CH35 extracts inhibited the growth of Bacillus subitillis (Bacillales: Bacillaceae) at 40 mu g/ml. All extracts strongly inhibited the growth of the fungus Fusarium oxysporum (Hypocreales: Nectriceae) but not that of Alternaria alternata (Pleosporales: Pleosporaceae). Contrastingly, a moderate to high inhibitory effect was denoted on the non-target biocontrol fungus Beauveria bassiana (Hypocreales: Clavivipitaceae). Crown Copyright (C) 2016 Published by Elsevier Inc. All rights reserved.
