Examinando por Autor "Sanz, Raquel"

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Effect of different non-ionic surfactants on the biodegradation of PAHs by diverse aerobic bacteria
(ELSEVIER, 2009) Bautista, Luis Fernando; Sanz, Raquel; Molina, M. Carmen; González, Natalia; Sánchez, David
The aim of this work was to evaluate the effect of several non-ionic surfactants (Tween-80, Triton X-100 and Tergitol NP-10) on the ability of different bacteria (Enterobacter sp., Pseudomonas sp. and Stenotrophomonas sp.) to degrade polycyclic aromatic hydrocarbons (PAHs). Bacterial cultures were performed at 25ºC in an orbital shaker under dark conditions in BHB medium containing 1% of surfactant and 500 mg¿l-1 of each PAH. Experiments performed with Tween-80 showed the highest cell density values and maximum specific growth rate because this surfactant was used as a carbon source by all bacteria. High degree of PAHs degradation (>90%) was reached in 15 days in all experiments. Toxicity increased at early times using Tween-80 but decreased to low levels in a short time after the firsts 24 h. On the other hand, Triton X-100 and Tergitol NP-10 were not biodegraded and toxicity kept constant along time. However, PAHs degradation rate was higher, especially by the action of Enterobacter sp. with Tween-80 or Triton X-100, depending on the microorganism used. Control experiments performed without surfactant showed a significant decrease in biomass growth rate with a subsequent loss of biodegradation activity likely due to a reduced solubility and bioavailability of PAHs in absence of surfactant.
Immobilization strategies for laccase from Trametes versicolor on mesostructured silica materials and the application to the degradation of naphthalene
(ELSEVIER, 2010) Bautista, L. Fernando; Morales, Gabriel; Sanz, Raquel
The oxidation of naphthalene by immobilized laccase from Trametes versicolor has been performed using diverse immobilization strategies on mesostructured silica materials. Laccase was immobilized by physical adsorption on several SBA-15 with different textural properties and by covalent attachment on functionalized SBA-15 prepared by co-condensation method (direct synthesis). The adsorption of laccase was partially reversible and showed some degree of lixiviation. However, covalently attached laccase to aminopropyl and aminobutyl functionalized SBA-15 exhibited important activity for the degradation of naphthalene with, respectively, 35% and 39%wt of removal in 5 hours. The aminopropyl biocatalyst retained higher activity after repeated uses than the corresponding aminobutyl.