Programa de Biologia Marinha e Ambientes Costeiros, Instituto de Biologia, Universidade Federal Fluminense, Niterói, RJ, Brazil.
Instituto Tecnológico Vale de Desenvolvimento Sustentável, Nazaré, Belém, PA, Brazil.
PLoS One. 2020 Oct 26;15(10):e0240486. doi: 10.1371/journal.pone.0240486. eCollection 2020.
High concentrations of metals in the environment alter bacterial diversity, selecting resistant and tolerant species. The study evaluated the selection of a potential bacterial strain from Sepetiba Bay-Rio de Janeiro, Brazil marine sediments to remove Cu and Pb. The bacterial strain isolated from the sediments was used in three different bioassays: (1) Cu at concentrations of 0 (control), 6 and 50 μg.mL-1; (2) Pb at concentrations of 0 (control), 6 and 50 μg.mL-1; (3) Cu + Pb in concentrations of 3 μg.mL-1 Cu + 3 μg.mL-1 Pb (6 μg.mL-1) and 25 μg.mL-1 Cu + 25 μg.mL-1 Pb (50 μg.mL-1). The number of cells and the enzymatic activities of dehydrogenases and esterases were quantified. Results of taxonomic identification indicated the selection of the Pseudomonas stutzeri W228 strain, showing a greater degree of similarity (±73%) with the database used. There was no significant variation in the number of cells, 108 cells.mL-1, which represents a high biomass production in the presence of stressors. However, we observed a reduction in dehydrogenase activity at all tested concentrations of Cu, Pb and Cu + Pb. The activity of esterase increased, indicating a higher energy demand to complete the bacterial life cycle. The study showed significant results for the absorption of Pb by the extracellular polymeric substances (EPS) and the efflux of Cu. The capacity of Pb absorption by EPS can be considered a resistance mechanism, as well as the efflux of Cu, so that the available EPS sites could be occupied by the most toxic ions demonstrating that Pseudomonas stutzeri is resistant to Pb and Cu.
环境中高浓度的金属会改变细菌的多样性，选择具有抗性和耐受性的物种。本研究评估了从巴西塞佩蒂巴湾-里约热内卢海洋沉积物中选择一种潜在细菌菌株来去除 Cu 和 Pb 的情况。从沉积物中分离出的细菌菌株用于三种不同的生物测定：（1）Cu 的浓度分别为 0（对照）、6 和 50 μg.mL-1；（2）Pb 的浓度分别为 0（对照）、6 和 50 μg.mL-1；（3）Cu + Pb 的浓度分别为 3 μg.mL-1 Cu + 3 μg.mL-1 Pb（6 μg.mL-1）和 25 μg.mL-1 Cu + 25 μg.mL-1 Pb（50 μg.mL-1）。细胞数量和脱氢酶和酯酶的酶活性被定量。分类鉴定结果表明选择了 Pseudomonas stutzeri W228 菌株，与使用的数据库具有较高的相似度（±73%）。在存在胁迫因素的情况下，细胞数量没有显著变化，为 108 个细胞.mL-1，这表示具有高生物质产量。然而，我们观察到所有测试浓度的 Cu、Pb 和 Cu + Pb 下脱氢酶活性降低。酯酶活性增加，表明为完成细菌生命周期需要更高的能量需求。该研究表明，细胞外多聚物（EPS）对 Pb 的吸收和 Cu 的外排具有显著效果。EPS 对 Pb 的吸收能力可被视为一种抗性机制，以及 Cu 的外排，因此可用的 EPS 位点可能被最毒的离子占据，表明 Pseudomonas stutzeri 对 Pb 和 Cu 具有抗性。
