Background: Consortia of specifically selected bacteria are often used in open fields for bioremediation purposes. However, a clear evaluation of the efficiency of the system requires detailed investigation. Objectives: The main objective of this work was to evaluate the efficiency of a bacterial consortium in reducing diesel fuel content of soil. Since the soil adopted for this investigation was coming from a real site interested by a long-term fuel spill, a well established oil tolerant and oil degrading microflora was supposed to be already present. Methods: Lab-scale biopiles were assembled with long term diesel fuel polluted soil and with unpolluted soil artificially contaminated with the same hydrocarbon. Inoculated and not inoculated samples were organized. Microbial community composition was determined by DGGE analysis. Results: DNA analysis performed on the long-term contaminated soil showed that the profile related to the inoculant by itself did not cluster with any of the profiles obtained from the biopiles. Since both the inoculated and not inoculated biopiles seems to be active in the biodegradation process, this could be due to the autochthonous microflora that experienced a strong and continuous selective pressure during 30 years polluted soil. After so long time the microbial community evolved in a hydrocarbon resistent and actively degrading population, so well established in that soil to prevent effective colonization b y newly introduced bacterial population. On the other hand, the results obtained from the unpolluted soil that was artificially contaminated, indicated that the bacterial consortium there released was able to colonize that soil and actively break down hydrocarbons. Conclusions: This results may suggest that the use of bacterial consortia could have chance to successfully perform i f promptly applied after the occurrence of the contamination, while long-term polluted soils would be much less receptive to newly introduced inoculants.
Preliminary test methods to evaluate biodegradation performance of petroleum hydrocarbons in biopile soil remediation: molecolar aspects
BASAGLIA, MARINA;CASELLA, SERGIO
2009
Abstract
Background: Consortia of specifically selected bacteria are often used in open fields for bioremediation purposes. However, a clear evaluation of the efficiency of the system requires detailed investigation. Objectives: The main objective of this work was to evaluate the efficiency of a bacterial consortium in reducing diesel fuel content of soil. Since the soil adopted for this investigation was coming from a real site interested by a long-term fuel spill, a well established oil tolerant and oil degrading microflora was supposed to be already present. Methods: Lab-scale biopiles were assembled with long term diesel fuel polluted soil and with unpolluted soil artificially contaminated with the same hydrocarbon. Inoculated and not inoculated samples were organized. Microbial community composition was determined by DGGE analysis. Results: DNA analysis performed on the long-term contaminated soil showed that the profile related to the inoculant by itself did not cluster with any of the profiles obtained from the biopiles. Since both the inoculated and not inoculated biopiles seems to be active in the biodegradation process, this could be due to the autochthonous microflora that experienced a strong and continuous selective pressure during 30 years polluted soil. After so long time the microbial community evolved in a hydrocarbon resistent and actively degrading population, so well established in that soil to prevent effective colonization b y newly introduced bacterial population. On the other hand, the results obtained from the unpolluted soil that was artificially contaminated, indicated that the bacterial consortium there released was able to colonize that soil and actively break down hydrocarbons. Conclusions: This results may suggest that the use of bacterial consortia could have chance to successfully perform i f promptly applied after the occurrence of the contamination, while long-term polluted soils would be much less receptive to newly introduced inoculants.
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