title: Rice seedling whole exudates and extracted alkylresorcinols induce stress-response in Escherichia coli biosensors.
abstract: A set of Escherichia coli sensor strains was used to evaluate the stress exerted on surrounding bacteria by germinating rice seed exudates. These biosensor strains contain Vibrio fischeri luxCDABE genes fused to the promoters of different genes involved in bacterial responses to environmental stresses. They provided clear evidence for a stress exerted by rice exudates, as shown by the induction of the universal stress protein gene uspA as well as genes of the heat shock regulon, grpE, lon and dnaK. The oxidative stress gene katG, and the post-transcriptional ompF regulator encoded by micF were also activated. The lack of derepression of recA, uvrA and alkA indicated that damage to the DNA was not induced in the E. coli strains tested. Interestingly, resorcinolic lipids extracted from rice root seedlings induced the same promoters as whole exudates, suggesting that these compounds may contribute to the stress exerted by seedling exudates. The results obtained with E. coli biosensors thus indicate that, in vivo, exudates may also exert a selective pressure on root-colonizing bacteria.
authors.affiliation: Laboratoire d'Ecologie Microbienne, UMR 5557 CNRS - Université Claude Bernard Lyon 1, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne cedex, France. lucie_miche@yahoo.fr
authors.forename: Lucie
authors.initials: L
authors.lastname: Miché
authors.forename: Shimshon
authors.initials: S
authors.lastname: Belkin
authors.forename: Rachel
authors.initials: R
authors.lastname: Rozen
authors.forename: Jacques
authors.initials: J
authors.lastname: Balandreau
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D015374:Biosensing Techniques; D004249:DNA Damage; D004926:Escherichia coli / Q000187:drug effects / Q000378:metabolism*; D005798:Genes, Bacterial; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D018869:Heat-Shock Response; D006358:Hot Temperature; D008163:Luminescent Measurements; D012275:Oryza / Q000737:chemistry*; D018384:Oxidative Stress; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D010936:Plant Extracts / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D012118:Resorcinols / Q000737:chemistry / Q000494:pharmacology*; D036226:Seedlings / Q000737:chemistry*; D014733:Vibrio / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D006360:Heat-Shock Proteins; D010936:Plant Extracts; D012118:Resorcinols; C078564:universal stress protein A, Bacteria; D010088:Oxidoreductases; C055198:LuxC protein, Bacteria