Mercury and methylmercury detoxification potential by sponge-associated bacteria

Area of Science:

• Environmental Microbiology
• Marine Biotechnology
• Toxicology

Background:

• Mercury (Hg) compounds, both ionic and organic, are significant cytotoxic and neurotoxic agents affecting humans and wildlife.
• Marine ecosystems can harbor microorganisms with unique metabolic capabilities for pollutant degradation.
• Sponge-associated bacteria represent a promising source of novel bioactive compounds and enzymes.

Purpose of the Study:

• To investigate the mercury (Hg) resistance profiles of bacteria associated with marine sponges.
• To explore the potential of these bacteria in detoxifying inorganic and organic mercury.
• To identify mechanisms of mercury resistance and detoxification in marine sponge-associated bacteria.

Main Methods:

• Isolation and cultivation of bacteria from marine sponges collected along the coast of Rio de Janeiro, Brazil.
• Screening of bacterial isolates for resistance to various concentrations of mercury (HgCl2 and methylmercury).
• Genomic analysis to detect the presence of mercury resistance genes (e.g., merA) and assessment of biosurfactant production.

Main Results:

• Out of 100 bacterial strains analyzed, 21 exhibited resistance to mercury (Hg).
• Fourteen strains demonstrated high resistance, growing at 100 µM HgCl2.
• Fifteen resistant strains possessed the merA gene and reduced Hg, while six produced biosurfactants, indicating potential sequestration mechanisms. Eleven strains tolerated methylmercury.

Conclusions:

• Marine sponge-associated bacteria possess significant potential for mercury (Hg) detoxification via enzymatic reduction or sequestration.
• These resistant bacterial strains could be valuable candidates for the bioremediation of mercury-polluted environments.
• The study highlights the ecological role of sponge microbiota in mitigating heavy metal toxicity.