TiO₂ exposure alters transition metal ion quota in Rhodococcus ruber GIN-1

Area of Science:

• Environmental microbiology
• Biogeochemistry
• Nanotoxicology

Background:

• Titanium dioxide (TiO2) nanoparticles are widely used, raising environmental and health concerns.
• Microbial interactions with engineered nanomaterials are crucial for understanding environmental fate and effects.
• Rhodococcus ruber is a bacterium known for its metabolic versatility and potential in bioremediation.

Purpose of the Study:

• To investigate the interaction between Rhodococcus ruber GIN-1 and micron-sized TiO2 particles.
• To quantify titanium accumulation in bacterial biomass after TiO2 exposure.
• To assess the impact of TiO2 exposure on cellular biometals in Rhodococcus ruber.

Main Methods:

• Exposure of Rhodococcus ruber GIN-1 cultures to micron-sized anatase and/or rutile TiO2 particles.
• Quantification of accumulated titanium in bacterial biomass using appropriate analytical techniques.
• Analysis of cellular concentrations of essential biometals (Fe, Zn, Mn, Cu, Al) before and after TiO2 exposure.

Main Results:

• Rhodococcus ruber GIN-1 accumulated significant concentrations of titanium (2.2 ± 0.2 mg kg-1) from TiO2 particles.
• Concomitant decreases in cellular iron (Fe) and zinc (Zn) were observed.
• Possible reduction in manganese (Mn) levels, while copper (Cu) and aluminum (Al) remained unaffected.

Conclusions:

• Rhodococcus ruber GIN-1 demonstrates the capacity to interact with and accumulate titanium from TiO2 particles.
• TiO2 exposure induces significant changes in bacterial cellular metal homeostasis, particularly affecting Fe and Zn.
• These findings highlight the potential for microbial mediation of titanium fate and associated biogeochemical cycling in contaminated environments.