Banca de DEFESA: ADRIELY FERREIRA DA COSTA NERY

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : ADRIELY FERREIRA DA COSTA NERY
DATA : 18/03/2021
HORA: 08:00
LOCAL: Porto Velho, via Plataforma google meet
TÍTULO:

BIOPROSPECTION OF MECURY-RESISTANT BACTERIA FROM THE GENE MerA IN THE MADEIRA RIVER BASIN

PALAVRAS-CHAVES:

Keywords: mercury, resistance, bacteria, Amazon region, water, sediment.

PÁGINAS: 62
GRANDE ÁREA: Ciências Biológicas
ÁREA: Ecologia
SUBÁREA: Ecologia de Ecossistemas
RESUMO:

Mercury is a metal that stands out for its toxicological potential, since the action of this element can lead to changes in the organism's intracellular transport systems, as well as negatively affect the functioning of the nervous system. The Amazon region, in the 1980s, was the scene of great gold mining activities, which still persists, to a lesser extent, with emphasis on the Madeira River basin, in the state of Rondônia, contributing considerably to the contamination of the local ecosystem. Despite the history of gold mining over the years, this is not the only point that draws attention regarding the emission of Hg in the Amazon region, since it has soils naturally rich in Hg, in addition to the burning of large forest areas resulting in the liberation of the metal reaching the aquatic systems. Another factor that can contribute to these emissions happen is the creation of lentic environments with the construction of dams for the generation of electricity, the activity that has been taking place in an increasingly intense manner in the Amazon. Despite the toxicity, both for eukaryotic cells and for prokaryotes, contaminated environments end up selecting resistant microorganisms, with adaptive mechanisms of enzymatic reduction of mercury species. Thus, a bioprospecting of microorganisms that can be used in the bioremediation of contaminated ecosystems constitutes the initial step in research aimed at transforming toxic compounds into less harmful compounds. In this context, the present study aimed to investigate the resistance of bacteria to Hg, from the merA gene. The bacteria were isolated from surface and bottom water samples and bottom sediment from a stretch of the Madeira River basin. The obtained isolates were evaluated for HgCl₂ concentrations, capable of inhibiting their growth, in addition to the detection of the merA resistance gene, responsible for the enzymatic reduction of Hg²⁺ to Hg⁰, by means of conventional PCR. In the study, 79 bacterial colonies were isolated, of which 18 showed tolerance to Hg above 20 µM. The 18 isolates, with greater tolerance, were submitted to PCR and identified as to the species. Of these, it was possible to verify the presence of the merA gene in 4 isolates, demonstrating the resistance of these strains genetically. For the identification of resistant bacterial species, sequencing of the 16S rRNA region was carried out. Of the resistant microorganisms identified in the sequencing, 2 belonged to the species Acinetobacter nosocomialis, 1 to Serratia marcescens, and 1 to Klebsiella quasipneumoniae, showing the predominance of Gram-negative isolates in terms of tolerance/resistance to Hg. According to the results obtained, in this work, it was possible to observe that bacteria isolated from bottom sediment showed higher levels of tolerance, compared to those isolated from water, highlighting the relationship of the different levels of tolerance with the place of origin of the strains evaluated. Bacteria prospected in the Amazon region have the potential to be used in future studies for the application in the bioremediation of Hg, since they have shown to be resistant to the metal because they have the merA gene.

MEMBROS DA BANCA:
Externo ao Programa - 1680831 - ADRIANA CRISTINA DA SILVA NUNES
Externo à Instituição - MARÍLIA HIGINO MUSSY - UFRJ
Externo ao Programa - 1905088 - RONALDO DE ALMEIDA
Presidente - 359961 - WANDERLEY RODRIGUES BASTOS