Detoxification and decolorization of environmental pollutants by marine microbial consortia

Author(s)

Gabriela Alves Licursi Vieira

• Document type: Doctoral Thesis
• Press: Rio Claro. 2017-02-22.
• Institution: Universidade Estadual Paulista (Unesp). Instituto de Biociências. Rio Claro
• Defense date: 2016-12-19
• Advisor: Lara Durães Sette

Abstract

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. (AU)

• FAPESP's process: 12/12622-3 - DETOXIFICATION AND DECOLORIZATION OF ENVIRONMENTAL POLLUTANTS BY MARINE MICROBIAL CONSORTIA
• Grantee: Gabriela Alves Licursi Vieira
• Support Opportunities: Scholarships in Brazil - Doctorate