Banca de DEFESA: FELIPHE LACERDA SOUZA DE ALENCAR

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : FELIPHE LACERDA SOUZA DE ALENCAR
DATE: 04/05/2020
TIME: 14:00
LOCAL: Videoconferência
TITLE:

BIOPROSPECTION OF Chromobacterium violaceum FOR LEAD BIORIMEDIATION: APPLICATIONS IN BIOTECHNOLOGY AND ENVIRONMENTAL HEALTH

KEY WORDS:

Chromobacterium violaceum; bioprospecting; bioremediation; electron microscopy; proteomics; lead.

PAGES: 203
BIG AREA: Outra
AREA: Ciências Ambientais
SUMMARY:

The presence of toxic waste in the environment can cause harm not only to ecological balance, but also to human health. This problem is intensified when the perimeter of industries approaches populated areas, especially those inserted in regions surrounding rivers, weirs and reservoirs, such as the municipality of Lages Pintadas, located in the semi-arid region of Rio Grande do Norte, which suffers impacts resulting from both anthropic action and natural radiation, with heavy metal lead as an important impacting residue. Given the above, we present the need for the development and application of management and maintenance tools for environments impacted by lead, based on the study of the bioremediation potential of different strains of Chromobacterium violaceum. The isolation and microbiological identification of the respective bacterial strains occurred according to the methodology recommended by the Standard Methods for Examinations of Water and Wastewater. The strains were tested for the pattern of lead resistance in decreasing concentrations and different exposure times, then evaluated by scanning electron microscopy different bacterial arrangements against the metal, followed by the evaluation by atomic absorption spectrophotometry of the levels of metallic removal tested in the presence of C. violaceum. Oxidative stress was based on the activity of the antioxidant enzyme catalase (CAT). After electrophoresis - SDS-PAGE, each lane was excised according to the protein density. Protein sequencing was performed in a liquid chromatography system coupled to a mass spectrometer. The observed data are promising, with regard to the viability of using C. violaceum as a bioremediation tool to combat and mitigate the problematic pollution and environmental contamination by heavy metals. The resistance profiles of C. violaceum in face of high concentrations of Pb (NO₃)₂ indicate the metabolic versatility of this organism. Both strains showed similar resistance patterns when exposed to the lowest concentrations of Pb (NO₃)₂, 1 to 5 mM. However, the SCV1 strain, isolated from the environment, showed a more efficient resistance pattern than the ATCC 12472 strain, standard strain, especially between concentrations of 7 to 10 mM. When comparing the efficiency regarding in vitro Pb (NO₃)₂ removal in the medium, the SCV1 strain was able to remove up to twice as much metal concentration when compared to ATCC. Observations under a scanning electron microscope (SEM) showed the ability of C. violaceum to withstand concentrations of up to 10 mM Pb (NO₃)₂, without, however, undergoing significant changes in its structure, maintaining its bacillary shape. The analysis of total proteins revealed a total of 1930 proteins in both strains. In ATCC 12472, 21.3% of proteins had transport-related functions, mainly associated with the ABC-type transport system. Complexation and biomolecular binding mechanisms were present in about 70% of the proteins of the ATCC strain and in 60% in the SCV1 strain, of which a large part was associated with the complexation of metals, such as iron, zinc, copper and manganese and magnesium. In addition, repair proteins, cell resistance and response to oxidative stress were identified in both strains, such as Glutathione-S-transferases. Most of the supra regulated proteins of both strains performed functions related to complexation, transport, efflux, or mechanisms associated with the repair of genetic material, response to oxidative stress and cell resistance. This is the first study on the resistance proteomics of C. violaceum against heavy metal lead. The relative metabolic efficiency observed in the wild strain of C. violaceum in relation to ATCC suggests that bacteria when exposed to certain polluting agents and contaminants tend to develop resistance mechanisms against the selective pressures imposed by the medium. Changes in the protein profile of C. violaceum under oxidative stress indicate metabolic reprogramming and reveal the important adaptability of this bacterium. Numerous so-called hypothetical proteins with a probable association with the transport of biomolecules, efflux systems and ionic complexation were identified in this study. Such observation opens up to the scientific field the possibility of studying and unraveling these proteins as possible candidates for bioremediation processes against lead and other heavy metals.

BANKING MEMBERS:
Presidente - 1674709 - VIVIANE SOUZA DO AMARAL
Interno - 707.819.324-59 - JULIO ALEJANDRO NAVONI - UFRN
Externa ao Programa - 1199127 - SILVIA REGINA BATISTUZZO DE MEDEIROS
Externo à Instituição - FABIO TEIXEIRA DUARTE - IFRN
Externa à Instituição - NATALY ALBUQUERQUE DOS SANTOS - UFPB