Toxicity of engineered TiO2 nanoparticles to Citarum River sediment bacteria: A preliminary study

The widespread application of titanium dioxide nanoparticles (TiO2 NPs) in consumer products impact the environment, especially the aquatic ecosystem. The more nano TiO2 products used due to human needs, the more negative impact. Herein, we report a preliminary toxicity study of two types of TiO2 NPs (rutile and anatase) on bacterial from sediment of Citarum River through the cell viability determination. A total of 10 bacteria has been successfully isolated and identified through 16S rRNA gene sequencing. For toxicity testing, the isolated bacteria were then exposed to 100 mg/L of TiO2 NPs suspension at 30 °C for 24 hours under natural light conditions. The results show that isolates bacterial in the samples were identified as Proteobacteria phylum belonging to the Actinobacteria, Betaproteobacteria, and Gammaproteobacteria classes. TiO2 NPs exhibited the highest growth inhibition to Citrobacter freundi (71.94% for rutile phase) and Enterobacter asburiae (79.24% for anatase phase). Rutile and anatase showed different effects in cell growth for the Actinobacteria (closely associated with Streptomyces sp.). Anatase induces cell growth (112.39%, cell viability), while the rutile phase is the other way around (74.35%, cell viability).