title: Biodegradation of diesel fuel by an Azolla-derived bacterial consortium.
abstract: The widely distributed water fern Azolla was investigated for use as an amendment in the bioremediation of fuel-contaminated environments. In a field experiment Azolla pinnata as well as Pistia stratiotes and Salvinia molesta were applied to plots containing soil that had been surface-contaminated with diesel fuel (2.4 L m(-2)) and flooded with water. The plants quickly died and bacterial flocs developed around the dead A. pinnata fronds. After 16 weeks, diesel concentrations (as determined by levels of gas chromatography-detectable hydrocarbons) in the plant-added plots were less than half that of the control plot, and concentrations of xylenes and ethylbenzene were 50-100 times lower. In laboratory experiments, a consortium composed of A. pinnata-derived bacteria displayed dense growth in a 4% diesel-containing mineral salts medium and was found to lower the fluorescence from aromatic compounds by approximately 50% after 19d. It is concluded that the observed enhancement of diesel degradation in the plant-added plots was due to the release of bacteria (bioaugmentation) and physiochemical improvement of the plot conditions (biostimulation).
authors.affiliation: Laboratory of Cell and Functional Biology, Faculty of Science, University of the Ryukyus, Nishihara, Okinawa, Japan.
authors.forename: Michael F
authors.initials: MF
authors.lastname: Cohen
authors.forename: Jolene
authors.initials: J
authors.lastname: Williams
authors.forename: Hideo
authors.initials: H
authors.lastname: Yamasaki
mesh_terms: D001419:Bacteria / Q000254:growth & development*; D001673:Biodegradation, Environmental; D029624:Ferns / Q000187:drug effects* / Q000254:growth & development; D005742:Gasoline / Q000032:analysis* / Q000633:toxicity; D007564:Japan; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000032:analysis* / Q000633:toxicity
chemical_list: D005742:Gasoline; D012989:Soil Pollutants