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Congresso Brasileiro de Microbiologia 2023
 		Resumo: 285-1

285-1

Resistance to heavy metals of bacteria from Brazilian deep aquatic environments

Autores:
Agatha do Canto Shubeita (PUCRS - Pontifícia Universidade Católica do Rio Grande do Sul) ; Rafaela Wong Davi (PUCRS - Pontifícia Universidade Católica do Rio Grande do Sul) ; Caroline Menegotto (PUCRS - Pontifícia Universidade Católica do Rio Grande do Sul) ; Renata Medina-silva (PUCRS - Pontifícia Universidade Católica do Rio Grande do Sul)

Resumo:
Microorganisms dominate aquatic environments. The contamination of these environments with heavy metals can promote selection of microbial resistance genes, which represents a risk to microbial ecology and human health. This study investigated the resistance to heavy metals of 24 bacterial isolates from samples of two deep-water environments in southern Brazil: Guarani Aquifer System (GAS) waters and marine sediment of the Rio Grande Cone (RGC). Pseudomonas, Bacillus, Paenibacillus, Lysinibacillus and Staphylococcus isolates from these samples were evaluated through minimum inhibitory concentration (MIC). For GAS isolates, were used Fe, Al, Se, and for marine isolates, Ni, Cu and Hg. Isolates with lowest MICs were exposed to Se and Hg during biofilm formation and analyzed throuhg scanning electronic microscopy (SEM). The DNA of isolates was extracted and a polymerase chain reaction (PCR) was performed to investigate the presence of resistance genes MerA in 8 RGC isolates and SelA and SelD in 5 GAS isolates. Results showed that 58%, 75% and 67% of GAS isolates had higher MIC than the reference strains for Fe, Al and Se, respectively. The RGC bacteria had Cu and Ni MICs equal (67% and 50%, respectively) or lower (25% and 33%, respectively) than the reference strains. Most GAS isolates formed intense biofilms under 24 hours. SEM revealed the presence of SeNPS and changes in bacterial morphology in Se-treated GAS isolates (Figures 1, 2) and a variety of microstructures in Hg-treated RGC isolates (Figures 3, 4). Three isolates from each environment showed genes involved in resistance to Se or Hg (Table 1). This study describes relevant information regarding metal resistance of bacteria from two Brazilian deep aquatic ecosystems, contributing to a deeper understanding of the impacts that heavy metals can induce in microbial ecosystems, which may represent a threat to human and non-human populations, under the principle of one health.

Palavras-chave:
 Microbial resistance, Heavy metals, Biofilms, Guarani Aquifer, Marine sediment


Agência de fomento:
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)