Biodegradation experiments of diesel (10,000 ppm) were performed in shaken flasks with liquid medium (adjusting the ratio C/ N ~ 20). In such assays, we tested the degrading activity of two defined mixed cultures, the first one (B-DMC) consisted of six bacterial strains; Bacillus cereus, Gordonia rubripertincta, Kocuria rosea, Bacillus subtilis strains 7A and 9A, and a non identified strain UAM10AP. The second defined mixed culture was formed by two fungal strains (F-DMC); Aspergillus terreus and Aspergillus carneus. Finally, a co-culture (CC) com‐ posed of all of the above strains was also tested. The degrading microorganisms were isolated and characterized as previously described (Diaz-Ramirez et al, 2003). In parallel, non-inocu‐ lated controls were prepared to quantify the hydrocarbons abiotic loss. In order to evaluate the biodegradability of diesel by exogenous and native hydrocarbondegrading microorganisms, an experimental trial was performed using artificially contami‐nated soil (~ 120,000 ppm of diesel), which has been biostimulated by addition of a commercial fertilizer (Triple 17), in order to get an initial C/N ratio of 20. Two treatments were established for this assay; a) bioaugmented soil (inoculated with exogenous microorganisms), and b) nonbioaugmented soil (only with the native microbiota).
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