Examinando por Autor "Molina, M.C."

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Assessment of the efficiency of in situ bioremediation techniques in a creosote polluted soil: change in bacterial community.
(ELSEVIER, 2013) Simarro, R; González, N.; Bautista, L.F.; Molina, M.C.
This work aimed to assess the effectiveness of different in situ bioremediation treatments (bioaugmentation, biostimulation, bioaugmentation and biostimulation, and natural attenuation) on creosote polluted soil. Toxicity, microbial respiration, creosote degradation and the evolution of bacterial communities were analyzed. Results showed that creosote decreased significantly in all treatments, and no significant differences were found between treatments. However, some specific polycyclic aromatic hydrocarbons (PAH) were degraded to a greater extent by biostimulation. The dominance of low temperatures (8.9ºC average) slowed down microbial creosote and PAH uptake and, despite significantly creosote degradation (>60%) at the end of the experiment, toxicity remained constant and high throughout the biodegradation process. DGGE results revealed that biostimulation showed the highest microbial biodiversity, although at the end of the biodegradation process, community composition in all treatments was different from that of the control assay (unpolluted soil). The active uncultured bacteria belonged to the genera Pseudomonas, Sphingomonas, Flexibacter, Pantoea and Balneimonas, the latter two of which have not been previously described as PAH degraders. The majority of the species identified during the creosote biodegradation belonged to Pseudomonas genus, which has been widely studied in bioremediation processes. Results confirmed that some bacteria have an intrinsic capacity to degrade the creosote without previous exposure.
Effect of surfactants on PAH biodegradation by a bacterial consortium and on the dynamics of the bacterial community during the process
(ELSEVIER, 2011) González, N.; Simarro, R.; Molina, M.C.; Bautista, L.F.; Delgado, L.; Villa, J.A.
The aim of this work was to evaluate the effect of a non-biodegradable (Tergitol NP-10) and a biodegradable (Tween-80) surfactant on growth, degradation rate and microbial dynamics of a polycyclic aromatic hydrocarbon (PAHs) degrading consortium (C2PL05) from a petroleum polluted soil, applying cultivable and non cultivable techniques. Growth and degradation rate were significantly lower with Tergitol NP-10 than that with Tween-80. Toxicity did not show any significant reduction with Tergitol NP-10 whereas with Tween-80 toxicity was almost depleted (30%) after 40 days. Regarding to the cultured bacteria, Pseudomonas and Stenotrophomonas groups were dominant during PAH degradation with Tergitol NP-10, whereas Enterobacter and Stenotrophomonas were dominant with Tween-80. DGGE analyses (PRIMER and MDS) showed that bacteria composition was more similar between treatments when PAHs were consumed than when PAHs concentration was still high. Community changes between treatments were a consequence of Pseudomonas sp., Sphingomonas sp., Sphingobium sp. and Agromonas sp.