In order to evaluate the remediation activity of oil degrading bacterial strains it is required to clearly distinguish between the intrinsic microbial activity of the soil under investigation and the activity of newly introduced inoculant strains. Previous investigations indicated that oil degrading bacterial strains, proven highly effective in lab-scale experiments, were shown not to enhance significantly the remediation of soil when the polluting agent was present in the soil for many years. The aim of this study was to evaluate, in areated soil laboratory columns, the biodegradation rate of diesel fuel in both a newly (system I) and a 30 years aged (system II) polluted soil inoculated and non inoculated with a dried consortium of bacterial strains. Total Recoverable Petroleum Hydrocarbons (TRPH) and Diesel Recoverable Oil (DRO) were constantly analysed by GC-FID and a study on the bacterial communities was performed by DNA soil extraction and ARDRA profiles. Total heterothrophs were also determined at different times by plating on Total count Agar (TCA) and TCA supplemented with 1% diesel fuel. Moreover, after characterization of the main bacterial strains released with the inoculant, their soil colonization was evaluated using specific antisera and immunological techniques coupled to 16S rDNA sequence analysis. A clear difference between the two systems was found in terms of rapidity and effectiveness of degradation, and dynamics of indigenous and newly introduced bacterial populations are presented and discussed. Acknowledgements This work was supported by Provincia di Belluno. The authors wish to thank Serenambiente SrL
Degradation of Diesel fuel in an Aged and in a Newly Polluted Soil using a Bacterial Consortium.
BASAGLIA, MARINA;BALDAN, ENRICO;SQUARTINI, ANDREA;CASELLA, SERGIO
2004
Abstract
In order to evaluate the remediation activity of oil degrading bacterial strains it is required to clearly distinguish between the intrinsic microbial activity of the soil under investigation and the activity of newly introduced inoculant strains. Previous investigations indicated that oil degrading bacterial strains, proven highly effective in lab-scale experiments, were shown not to enhance significantly the remediation of soil when the polluting agent was present in the soil for many years. The aim of this study was to evaluate, in areated soil laboratory columns, the biodegradation rate of diesel fuel in both a newly (system I) and a 30 years aged (system II) polluted soil inoculated and non inoculated with a dried consortium of bacterial strains. Total Recoverable Petroleum Hydrocarbons (TRPH) and Diesel Recoverable Oil (DRO) were constantly analysed by GC-FID and a study on the bacterial communities was performed by DNA soil extraction and ARDRA profiles. Total heterothrophs were also determined at different times by plating on Total count Agar (TCA) and TCA supplemented with 1% diesel fuel. Moreover, after characterization of the main bacterial strains released with the inoculant, their soil colonization was evaluated using specific antisera and immunological techniques coupled to 16S rDNA sequence analysis. A clear difference between the two systems was found in terms of rapidity and effectiveness of degradation, and dynamics of indigenous and newly introduced bacterial populations are presented and discussed. Acknowledgements This work was supported by Provincia di Belluno. The authors wish to thank Serenambiente SrLPubblicazioni consigliate
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