Neusa Figueiredo*, Laura Silva, Vasco Branco, Cristina Carvalho, Marta Martins
The coexistence in aquatic systems of chemical and physical contaminants, such as Mercury (Hg) and Micro-plastics (MPs, Ø <5 mm), is an intricate problem. Mercury is well known for its toxicological effects and MPs, due to their polymeric properties, can interact with chemicals, such as Hg, by absorbing them in their surface. Beside this, MPs can act as a surface of attachment for microorganisms. Knowing that, microorganisms are the key player in Hg natural detoxification processes in aquatic systems, the following questions arise: Does the presence of MPs affect microbial-mediated Hg-detoxification? To answer this, Hg-resistant microorganisms were isolated from Hg-contaminated area of the Tagus estuary and the most Hg-resistant strains were selected to assess the effect of polystyrene MPs (PS-MPs) on the Hg-detoxification process. After up to 5 days of incubation with Hg and Hg plus PS-MPs, culture medium and PS-MPs were collected to assess the: 1) Hg-removal; 2) Acute toxicity of the supernatant; 3) pH variations of the supernatant and 3) Bacteria association with PS-MPs. The isolates selected for this study (strains PWLO and PWBL) were identified through the amplification of 16S rRNA as Pseudomonas sp. The results demonstrated that: (i) Both strains are resistant to Hg and can remove Hg2+ from the liquid medium and (ii) The presence of PSMPs affects Hg-removal mediated by the strain PWLO and consequently the detoxification processes. Thus, this set of data highlight the impact that PS-MPs may have on Hg natural-occurring detoxification process mediated by Hg-resistant bacteria in aquatic ecosystems.
Published Date: 2025-03-19; Received Date: 2024-02-12
