title: Evaluation of phytotoxicity and ecotoxicity potentials of a cyanobacterial extract containing microcystins under realistic environmental concentrations and in a soil-plant system.
abstract: The impact of a crude extract of Microcystis aeruginosa (PCC7820) containing 14 microcystin variants was investigated on seeds germination and radicles development of four agricultural plants: two tomato varieties Solanum lycopersicum (MicroTom and Saint-Pierre), the wheat Triticum aestivum and the lettuce Lactuca sativa. In addition, the effect of 14 d-exposure to irrigation water containing realistic concentrations of microcystins (0-0.1 mg eq. microcystin-LRL(-1)) on the tomato MicroTom seedling growth was further evaluated on roots and aerial part biomasses. Impacts on soil bacterial parameters, as such extracellular enzymatic activities, nitrification activity and abundances of ammonia-oxidizing microorganisms were also investigated. In germination-test, the cyanobacterial extract inhibited only the germination of the wheat seeds, with an EC50 of 11 mg eq. microcystin-LRL(-1); which is 13 times lower than that of the cadmium chloride (EC50 of 145 mg L(-1)). Moreover, the cyanobacterial extract containing low concentrations of microcystins increased the growth of primary roots; however, high concentrations decreased it for all plants except for the wheat. In the soil-plant approach, only aerial part biomass of the tomato MicroTom was enhanced significantly. In addition, only soil nitrification potential and ammonia-oxidizing bacterial abundances were consistently impacted. A significant positive correlation (r=0.56) was found between the increase of nitrification potential and abundances of ammonia-oxidizing bacteria. This work suggested, that exposure to a cyanobacterial extract containing realistic environmental microcystins concentrations could affect seed germination, depending plant species. It was also highlighted, for the first time, disturbances in soil bacteria functioning, evidences on soil nitrification process.
authors.affiliation: INRA, UMR1402 ECOSYS, F-78026 Versailles, France; Laboratoire Ecologie, Systématique et Evolution, UMR8079, Univ. Paris-Sud/CNRS/AgroParisTech, Université Paris-Sud, F-91405 Orsay, France.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Corbel
authors.affiliation: INRA, UMR1402 ECOSYS, F-78026 Versailles, France; AgroParisTech, UMR1402 ECOSYS, F-78026 Versailles cedex, France.
authors.forename: Christian
authors.initials: C
authors.lastname: Mougin
authors.affiliation: INRA, UMR1347 Agroécologie, F-21000 Dijon, France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Martin-Laurent
authors.affiliation: INRA, UMR1402 ECOSYS, F-78026 Versailles, France; AgroParisTech, UMR1402 ECOSYS, F-78026 Versailles cedex, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Crouzet
authors.affiliation: INRA, UMR1347 Agroécologie, F-21000 Dijon, France.
authors.forename: David
authors.initials: D
authors.lastname: Bru
authors.affiliation: INRA, UMR1402 ECOSYS, F-78026 Versailles, France; AgroParisTech, UMR1402 ECOSYS, F-78026 Versailles cedex, France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Nélieu
authors.affiliation: Laboratoire Ecologie, Systématique et Evolution, UMR8079, Univ. Paris-Sud/CNRS/AgroParisTech, Université Paris-Sud, F-91405 Orsay, France. Electronic address: noureddine.bouaicha@u-psud.fr.
authors.forename: Noureddine
authors.initials: N
authors.lastname: Bouaïcha
mesh_terms: D001427:Bacterial Toxins / Q000032:analysis / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D018525:Germination / Q000187:drug effects; D018545:Lactuca / Q000187:drug effects* / Q000254:growth & development; D018551:Solanum lycopersicum / Q000187:drug effects* / Q000254:growth & development; D052998:Microcystins / Q000032:analysis / Q000633:toxicity*; D046931:Microcystis / Q000737:chemistry*; D058465:Nitrification / Q000187:drug effects; D018517:Plant Roots / Q000187:drug effects; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development; D012639:Seeds / Q000187:drug effects / Q000254:growth & development; D012988:Soil Microbiology; D013045:Species Specificity; D013997:Time Factors; D014908:Triticum / Q000187:drug effects* / Q000254:growth & development
chemical_list: D001427:Bacterial Toxins; D052998:Microcystins; C078588:microcystin
keywords: Ammonia-oxidizing bacteria; Microcystins; Nitrification; Plant growth; Seed germination; Soil enzymatic activities