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(44-10) Evolution of PAHs degrading community during the PAHs biodegradation process. Lors, Christine*,1, Mossmann, Jean-Remi1, Sahut, Claire1, 1 CNRSSP, 930, Boulevard Lahure, Douai, France ABSTRACT- PAHs are common pollutants in soil sof former coke facility sites.In order to understand the fate and behaviour of those compounds in soils, biodegradation was studied because this process is often invoked to explain PAHs concentration decrease in soils. The goal of this study is to monitor the evolution of PAHs degrading community during a biodegradation experiment. To achieve this, degrading populations were determined at different steps during the experiment. Investigations were carried out in a respirometer on a soil sampled from a former coke site. This soil contained about 1 g/kg dry soil of the 16 PAHs from the US EPA list and a metallic pollution in Zn, Pb, Cu and Cd, reaching about 1 g/kg dry soil. Respirometric experiments were carried out in solid phase over a period of 12 months, at 20 C, in aerobic conditions. Degradation was assessed by following the decrease in PAHs concentration with time in soil samples. The microbial activity was determined by monitoring O2-consumption and CO2-production. The PAHs degrading microflora in soil was studied at different periods of time, corresponding to different phases of degradation. The enumeration of PAHs degrading microflora was determinated on 96-well microplates according to the method of Stieber et al. (1994) with PAH used as sole carbon and energy source. Selected PAHs were naphtalene, phenanthrene, anthracene, fluorene, fluoranthene. PAHs degraders were characterized by their phenotypic characteristics. It is expected from this work to evidence specific degrading populations at the different key steps of the experimental degradation pattern. Key words: PAHS degrading populations, PAHs, biodegradation, soil |
