title: Double-tagged fluorescent bacterial bioreporter for the study of polycyclic aromatic hydrocarbon diffusion and bioavailability.
abstract: Bacterial degradation of polycyclic aromatic hydrocarbons (PAHs), ubiquitous contaminants from oil and coal, is typically limited by poor accessibility of the contaminant to the bacteria. In order to measure PAH availability in complex systems, we designed a number of diffusion-based assays with a double-tagged bacterial reporter strain Burkholderia sartisoli RP037-mChe. The reporter strain is capable of mineralizing phenanthrene (PHE) and induces the expression of enhanced green fluorescent protein (eGFP) as a function of the PAH flux to the cell. At the same time, it produces a second autofluorescent protein (mCherry) in constitutive manner. Quantitative epifluorescence imaging was deployed in order to record reporter signals as a function of PAH availability. The reporter strain expressed eGFP proportionally to dosages of naphthalene or PHE in batch liquid cultures. To detect PAH diffusion from solid materials the reporter cells were embedded in 2 cm-sized agarose gel patches, and fluorescence was recorded over time for both markers as a function of distance to the PAH source. eGFP fluorescence gradients measured on known amounts of naphthalene or PHE served as calibration for quantifying PAH availability from contaminated soils. To detect reporter gene expression at even smaller diffusion distances, we mixed and immobilized cells with contaminated soils in an agarose gel. eGFP fluorescence measurements confirmed gel patch diffusion results that exposure to 2-3 mg lampblack soil gave four times higher expression than to material contaminated with 10 or 1 (mg PHE) g(-1).
authors.affiliation: Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland.
authors.forename: Robin
authors.initials: R
authors.lastname: Tecon
authors.forename: Olivier
authors.initials: O
authors.lastname: Binggeli
authors.forename: Jan R
authors.initials: JR
authors.lastname: van der Meer
mesh_terms: D001673:Biodegradation, Environmental; D001682:Biological Availability; D019117:Burkholderia / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D005456:Fluorescent Dyes / Q000032:analysis; D015870:Gene Expression / Q000187:drug effects; D005798:Genes, Bacterial / Q000187:drug effects; D017930:Genes, Reporter / Q000187:drug effects; D008164:Luminescent Proteins / Q000032:analysis / Q000235:genetics; D009281:Naphthalenes / Q000378:metabolism / Q000633:toxicity; D010616:Phenanthrenes / Q000378:metabolism / Q000633:toxicity; D011084:Polycyclic Aromatic Hydrocarbons / Q000378:metabolism* / Q000633:toxicity; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000378:metabolism* / Q000633:toxicity
chemical_list: D005456:Fluorescent Dyes; D008164:Luminescent Proteins; D009281:Naphthalenes; D010616:Phenanthrenes; D011084:Polycyclic Aromatic Hydrocarbons; D012989:Soil Pollutants; C031721:naphthalene; C031181:phenanthrene