title: Bioaugmentation with engineered endophytic bacteria improves contaminant fate in phytoremediation.
abstract: Phytoremediation of volatile organic contaminants often proves not ideal because plants and their rhizosphere microbes only partially degrade these compounds. Consequently, plants undergo evapotranspiration that contaminates the ambient air and, thus, undermines the merits of phytoremediation. Under laboratory conditions, endophytic bacteria equipped with the appropriate degradation pathways can improve in planta degradation of volatile organic contaminants. However, several obstacles must be overcome before engineered endophytes will be successful in field-scale phytoremediation projects. Here we report the first in situ inoculation of poplar trees, growing on a TCE-contaminated site, with the TCE-degrading strain Pseudomonas putida W619-TCE. In situ bioaugmentation with strain W619-TCE reduced TCE evapotranspiration by 90% under field conditions. This encouraging result was achieved after the establishment and enrichment of P. putida W619-TCE as a poplar root endophyte and by further horizontal gene transfer of TCE metabolic activity to members of the poplar's endogenous endophytic population. Since P. putida W619-TCE was engineered via horizontal gene transfer, its deliberate release is not restricted under European genetically modified organisms (GMO) regulations.
authors.affiliation: Centre for Environmental Sciences, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek, Belgium.
authors.forename: Nele
authors.initials: N
authors.lastname: Weyens
authors.forename: Daniel
authors.initials: D
authors.lastname: van der Lelie
authors.forename: Tom
authors.initials: T
authors.lastname: Artois
authors.forename: Karen
authors.initials: K
authors.lastname: Smeets
authors.forename: Safiyh
authors.initials: S
authors.lastname: Taghavi
authors.forename: Lee
authors.initials: L
authors.lastname: Newman
authors.forename: Robert
authors.initials: R
authors.lastname: Carleer
authors.forename: Jaco
authors.initials: J
authors.lastname: Vangronsveld
mesh_terms: D001673:Biodegradation, Environmental; D018014:Gene Transfer Techniques; D030781:Organisms, Genetically Modified / Q000235:genetics / Q000378:metabolism; D018526:Plant Transpiration / Q000502:physiology; D032107:Populus / Q000033:anatomy & histology / Q000378:metabolism / Q000382:microbiology; D016958:Pseudomonas putida / Q000235:genetics / Q000378:metabolism; D012336:RNA, Ribosomal, 16S / Q000235:genetics / Q000378:metabolism; D055549:Volatile Organic Compounds / Q000737:chemistry / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000378:metabolism*; D014881:Water Supply / Q000032:analysis
chemical_list: D012336:RNA, Ribosomal, 16S; D055549:Volatile Organic Compounds; D014874:Water Pollutants, Chemical