Destoxificação e descoloração de poluentes ambientais por consórcios microbianos marinhos
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Data
2016-12-19
Autores
Vieira, Gabriela Alves Licursi [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Considerando a importância dos processos de biorremediação, o presente trabalho teve como objetivo principal avaliar o potencial de consórcios microbianos, constituídos por quatro fungos filamentosos isolados de invertebrados marinhos e duas bactérias recuperadas de reservatório de petróleo, na destoxificação de poluentes ambientais, por meio da sobrevivência do microcrustáceo Artemia sp. e da luminescência da bactéria Vibrio fischeri. Após estudos de antagonismo entre os micro-organismos, foram estruturados oito consórcios microbianos, em diferentes combinações. Os consórcios foram usados, isoladamente, para avaliar a toxicidade dos poluentes ambientais corante têxtil RBBR (Remazol Brilliant Blue R), óleo diesel e hidrocarbonetos policíclicos aromáticos. Dentre os consórcios estudados, o consórcio 3, composto por dois fungos filamentosos e pelas duas bactérias, apresentou melhores resultados de destoxificação do corante RBBR e óleo diesel, após sete dias de cultivo a 28 oC e 140 rpm. As enzimas ligninolíticas apresentaram atividade baixa ou ausente no teste feito com o corante e com o óleo diesel. Para o benzo[a]pireno (BaP), apesar de ter havido uma produção mais expressiva de enzimas ligninolíticas, os resultados de destoxificação foram incoerentes, por não apresentar toxicidade mesmo em elevadas concentrações. Sendo assim, no presente estudo o consórcio 3 foi empregado na otimização da destoxificação e descoloração do corante RBBR. Os resultados de dois planejamentos do tipo Plackett-Burman (PB1 e PB2) e um DCCR (Delineamento Composto Central Rotacional) revelaram que as melhores condições de destoxificação/descoloração foram obtidas no ensaio 11 do PB1 e no ensaio 2 do PB2. As condições de cultivo desses dois ensaios foram submetidas a experimentos de validação, porém somente a condição do ensaio 2 do PB2 (inóculo de 4 cilindros de 0,5 cm de cada fungo e 4 mL de cada bactéria (DO 0,4), 1 g/50 mL de farelo de trigo, 100 % de água do mar, pH 8 e 500 ppm de RBBR) apresentou resultados coerentes (52 % de destoxificação e 87 % de descoloração). A atividade de enzimas ligninolíticas na validação foi baixa ou ausente. As análises de FTIR (Fourier Transform Infrared Spectroscopy) resultaram em diferenças no padrão de bandas do corante, quando comparadas às bandas do bioensaio e do controle, indicando atuação dos micro-organismos no processo de descoloração. Os estudos dos metatranscriptomas do experimento de validação (bioensaio e controle) revelaram diferenças na expressão gênica de enzimas específicas envolvidas no processo de degradação de compostos xenobióticos, com destaque para dioxigenase e mono-oxigenases. Tais resultados evidenciam o papel do consórcio microbiano, principalmente das bactérias, na destoxificação, descoloração e degradação do corante têxtil RBBR. Os resultados do presente trabalho demonstram a importância da aplicação do planejamento experimental e da metatranscriptômica para o estudo de destoxificação e degradação de poluentes ambientais, abrindo perspectivas para novos estudos envolvendo os micro-organismos do consórcio selecionado.
Taking into account the relevance of bioremediation processes, the present work aimed to evaluate the potential of microbial consortia composed by four filamentous fungi isolated from marine invertebrates and two bacteria recovered from oil reservoirs in the detoxification of environmental pollutants, through the survival of the microcrustacean Artemia sp. and the luminescence of the bacterium Vibrio fischeri. After studies of antagonism between the microorganisms, eight microbial consortia were structured in different combinations. The consortia were tested separately against the environmental pollutants RBBR (Remazol Brilliant Blue R) textile dye, diesel oil, and polycyclic aromatic hydrocarbons. Among the consortia studied, the consortium 3, composed of two filamentous fungi and two bacteria presented better results of RBBR dye and diesel detoxification after seven days at 28 oC and 140 rpm. Ligninolytic enzymes showed low or absent activity in the experiments containing RBBR and diesel. For benzo[a]pyrene (BaP), although there was a more expressive production of ligninolytic enzymes, the results of detoxification were incoherent, since no toxicity was showed even at high concentrations. Therefore, in the present study the consortium 3 was used to optimize detoxification and discoloration of RBBR dye. Results from two Plackett-Burman designs (PB1 and PB2) and one CCD (Central Composite Design) revealed that the best conditions for detoxification/ discoloration were obtained in the assay 11 from PB1 and assay 2 from PB2. The culture conditions of this two assays were submitted to validation experiments, however only assay 2 from PB2 (4 cylinders (0.5 cm) of each fungus, and 4 mL of each bacteria (OD 0.4), 1 g/50 mL wheat bran, 100 % artificial sea water, pH 8, and 500 ppm RBBR) presented consistent results (52 % detoxification and 87 % discoloration). The activity of ligninolytic enzymes in the validation experiments was low or absent. Fourier Transform Infrared Spectroscopy (FTIR) analyzes showed difference in the dye bands pattern in comparison to the bioassay and control bands, indicating the microbial performance in the process of dye discoloration. Metatranscriptome studies in the validation experiments (bioassay and control), revealed a differential gene expression of specific enzymes involved in the degradation of xenobiotic compounds, mainly dioxygenase and monooxygenases. These results highlight the role of the microbial consortium, mainly the bacteria, in the detoxification, discoloration, and degradation of the RBBR textile dye. Results from the present work demonstrate the importance of applying environmental design and metatranscriptomic approaches to the study of detoxification and degradation of environmental pollutants, opening perspectives for new studies involving the microorganisms of the selected consortium.
Taking into account the relevance of bioremediation processes, the present work aimed to evaluate the potential of microbial consortia composed by four filamentous fungi isolated from marine invertebrates and two bacteria recovered from oil reservoirs in the detoxification of environmental pollutants, through the survival of the microcrustacean Artemia sp. and the luminescence of the bacterium Vibrio fischeri. After studies of antagonism between the microorganisms, eight microbial consortia were structured in different combinations. The consortia were tested separately against the environmental pollutants RBBR (Remazol Brilliant Blue R) textile dye, diesel oil, and polycyclic aromatic hydrocarbons. Among the consortia studied, the consortium 3, composed of two filamentous fungi and two bacteria presented better results of RBBR dye and diesel detoxification after seven days at 28 oC and 140 rpm. Ligninolytic enzymes showed low or absent activity in the experiments containing RBBR and diesel. For benzo[a]pyrene (BaP), although there was a more expressive production of ligninolytic enzymes, the results of detoxification were incoherent, since no toxicity was showed even at high concentrations. Therefore, in the present study the consortium 3 was used to optimize detoxification and discoloration of RBBR dye. Results from two Plackett-Burman designs (PB1 and PB2) and one CCD (Central Composite Design) revealed that the best conditions for detoxification/ discoloration were obtained in the assay 11 from PB1 and assay 2 from PB2. The culture conditions of this two assays were submitted to validation experiments, however only assay 2 from PB2 (4 cylinders (0.5 cm) of each fungus, and 4 mL of each bacteria (OD 0.4), 1 g/50 mL wheat bran, 100 % artificial sea water, pH 8, and 500 ppm RBBR) presented consistent results (52 % detoxification and 87 % discoloration). The activity of ligninolytic enzymes in the validation experiments was low or absent. Fourier Transform Infrared Spectroscopy (FTIR) analyzes showed difference in the dye bands pattern in comparison to the bioassay and control bands, indicating the microbial performance in the process of dye discoloration. Metatranscriptome studies in the validation experiments (bioassay and control), revealed a differential gene expression of specific enzymes involved in the degradation of xenobiotic compounds, mainly dioxygenase and monooxygenases. These results highlight the role of the microbial consortium, mainly the bacteria, in the detoxification, discoloration, and degradation of the RBBR textile dye. Results from the present work demonstrate the importance of applying environmental design and metatranscriptomic approaches to the study of detoxification and degradation of environmental pollutants, opening perspectives for new studies involving the microorganisms of the selected consortium.
Descrição
Palavras-chave
Poluentes ambientais, Consórcios microbianos, Biodegradação, Toxicidade aguda, Fungos derivados de ambiente marinho, Enzimas ligninolíticas, Environmental pollutants, Microbial consortia, Biodegradation, Acute toxicity, Marine-derived fungi, Ligninolytic enzymes