Degradação de fenantreno em latossolo: efeito da concentração do contaminante e da adição de surfactina

• Ano de defesa: 2011
• Autor(a) principal: Morais, Daniel Kumazawa
• Orientador(a): Tótola, Marcos Rogério
• Banca de defesa: Parreira, Adriano Guimarães
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Microbiologia Agrícola
• Departamento: Associações micorrízicas; Bactérias láticas e probióticos; Biologia molecular de fungos de interesse
• País: BR
• Palavras-chave em Português: Biodegradação; Inóculo; Fenantreno; Surfactina e HPA
• Palavras-chave em Inglês: Biodegradation; Inoculum; Phenanthrene; Surfactin and HPA
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOSSANIDADE::MICROBIOLOGIA AGRICOLA
• Link de acesso: http://locus.ufv.br/handle/123456789/5347

Polycyclic aromatic hydrocarbons (PAH) consist exclusively of carbon and hydrogen atoms arranged in a linear, angular or clustered. Several PAH suffer enzymatic activation and tend to bind to DNA, causing mutations and replication errors. Many of these molecules are known to be toxic, mutagenic and carcinogenic. The PAH are recalcitrant compounds due to its low water solubility and high sorption to soil. The use of biosurfactants has been an option usually effective for removing hydrophobic organic contaminants in complex matrices such as soil. The surfactin is a lipopeptide synthesized by Bacillus subtilis and highly effective in reduction of tension between water and hydrophobiccompounds.Unlike of an exhaustive extraction, the biosurfactants act by increasing the bioavailability of the contaminant and facilitates its degradation.In this work the experiment of phenanthrene biodegradation was conducted in clayed soils contaminated with 14C-phenanthrene and 4 12C-phenanthrene concentrations (1, 10, 40 and 100 mg g-1). Biodegradation was evaluated with the addition of supplements: surfactin (0.825 mg g-1), yeast extract (1.0 mg g-1) and an inoculum (30 mg g-1) obtained from the addition of diesel to a compost made of the municipal solid waste, for enrichment of microorganisms degraders of hydrocarbons. The flasks were kept at 35 °C for 49 days. The 14CO2 produced was captured in scintillation vials containing 2 ml of KOH (1 mol L-1). The bottles were changed on days 8, 18, 25, 32, 37, 44 and 49. After replacing the vials on the thirtieth-second day, was made a second application of surfactin (0.230 mg g-1) in all treatments. The highest degradation activity was achieved in the first 8 days of incubation, only treatments that received the inoculum. After the eighth day until the new surfactin supplementation (32 days), increased activity was not significant in any of the treatments. The activity increased again after the addition of surfactin further, but at a lower rate than achieved in the first 8 days. This result was attributed to the lower concentration of surfactin and the effects of adsorption of phenanthrene to the soil. The degradation activity in samples with the highest concentration of phenanthrene (100 mg g-1) did not differ in the treatments with and without surfactin. This result suggests that the concentration of bioavailable phenanthrene on this dose remained high enough to sustain the activity of degradation. Supplementation with yeast extract resulted in a lower degradation activity in treatments with 10, 40 and 100 mg g-1 of phenanthrene. In the treatments with the lowest dose of phenanthrene (1 mg g-1), yeast extract stimulated the degradation of the contaminant. It is concluded that supplementation with yeast extract stimulated the degradation of surfactin, which resulted in reducing the degradation of phenanthrene in higher concentrations of the contaminant. The results of the work indicate that the bioremediation of soils contaminated with PAH requires the maintenance of solubilizing agents such as surfactin. Due to the rapid degradation of biosurfactant on the ground, it is suggested that the best strategy is to inoculate microorganisms producers of this class of compounds and the maintenance of favorable conditions to ensure the production of biosurfactants in situ, during the process of bioremediation.