Banca de DEFESA: KAMILLA KARLA DA SILVA BARBALHO

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : KAMILLA KARLA DA SILVA BARBALHO
DATE: 20/07/2021
TIME: 13:30
LOCAL: Videoconferência - Link para acesso: meet.google.com/smh-gmyv-zqp
TITLE:

Characterization of communities and bacterial isolates obtained from oil samples from Brazilian pre-salt under cultivation in the presence of CO₂

KEY WORDS:

Brazilian pre-salt, bioremediation, metagenomics, oil, microorganisms.

PAGES: 150
BIG AREA: Ciências Biológicas
AREA: Bioquímica
SUMMARY:

Microorganisms represent the largest biomass on Earth and are directly related to biogeochemical cycles. It has been described that microbial activity affects the production chain related to the oil and gas sector, being of interest the knowledge about the microbiology associated with reservoirs, aiming the optimization of the production chain, as well as the mitigation of environmental impacts due to environmental contamination by hydrocarbons. The Brazilian pre-salt reservoirs are extreme environments with high carbon dioxide (CO₂) concentration and high depth, whose microbiology is still poorly understood. The objective of this work was to characterize bacterial communities and isolates obtained from a sample of pre-salt oil submitted to cultivation at high CO₂ concentration. From an oil sample, six consortia were obtained and analyzed, organized in two groups: three undefined microbial consortia grown at high CO₂ concentration and the other three obtained from the same sample under atmospheric aeration and later submitted to high CO₂ concentrations. The microbial consortia were characterized for: i) biosurfactant (BS) production; ii) growth curve in the presence of hydrocarbons as carbon source; and iii) taxonomic and functional characterization by metagenomic sequencing. Functional assays of the consortia showed that three are able to produce BS molecules capable of generating emulsion, whereas none of the consortia is able to disperse oil. The growth curves showed that five consortia are able to grow in the absence of external carbon sources, indicating the occurrence of inorganic carbon fixation, which was corroborated by the metagenomic sequencing of the consortia via identification of sequences assigned to the genus Ochrobactrum, which is able to fix carbon. In the consortia, the most abundant phyla were Proteobacteria, Actinobacteria, and Firmicutes, and the consortia submitted to high CO₂ concentration, after growing in O₂, were more diverse than the consortia grown in high CO₂ concentration. As for the metabolic profile, the most enriched pathways in the consortia grown in CO₂ were the amino acid metabolism and carbohydrate metabolism pathways. Nineteen bacterial isolates were obtained from the consortia, and nine were characterized and tested. For the isolates the following assays were performed: i) BS production, ii) hydrocarbon degradation capacity, iii) cellular hydrophobicity, and iv) enzymatic activity of hydrolases. Of these, five were able to degrade between 50% and 80% of the xylene and toluene fractions, and eight others degraded 100% of the gasoline, diesel and kerosene fractions. It is concluded that the growth of undefined consortia in O₂ leads to a greater diversity of microorganisms, that CO₂ inhibits BS production, and that isolates and microbial consortia from the pre-salt show promise as a source of bioremediation products, as well as hydrolases with potential industrial application.

BANKING MEMBERS:
Presidente - 1149647 - LUCYMARA FASSARELLA AGNEZ LIMA
Externo à Instituição - FABIANO LOPES THOMPSON - UFRJ
Externa à Instituição - VÂNIA MARIA MACIEL MELO - UFC