G Arumugam, RR Thanighaiarassu and P Sandhya

The TiO₂ toxicity resisted by waste water bacterial isolates. The waste water samples are collected and TiO₂ nanoparticles stability with waste water is studied by measuring hydrodynamic size by dynamic light scattering at different time intervals 0,6,12 and 24 hrs was carried out using 90 plus Particle Size Analyzer, Brookhaven Instruments, USA. Then from this waste water five bacterial pure culture isolated and five synergistic bacterial consortium also cultivated. The titanium nanoparticles showed its toxicity effect on the bacterial isolates Bacillus flexus, Brevundimonas diminuta, Exiguobacterium indicum, Exiguobacterium acetylicum, Pseudomonas nitroreducens) which are isolated from the waste water . Bacterial cell viability assay was proceded by standard plate count assay at 6, 12 and 24 hrs time intervals and 0.25, 0.5 and 1 µg/mL of titanium nanoparticles concentrations. Cell viability is statistically significant with respect to both dark and UVA conditions. The free radicals super oxide dismutase the reactive oxygen species level of treated (1µg/mL) of TiO₂ nanoparticles on all five bacterial species and consortium was found to increased in dark condition and increased UVA condition. The biofilm mass formed in the presence of TiO2 nanoparticles (1 µg/mL) of all five bacterial isolates and consortium is estimated to be increased in dark condition and UVA condition at optical density 590nm. Although biofilm formation in consortium was found to be higher when compared to individual isolates it was not significant when compared to UVA and dark condition. The extracted EPS from the TiO₂ nanoparticles (0.25, 0.50, 1µg/mL, 24 hrs) from individual five bacteria and the consortium was showed bacterial resistance against the toxicity produced. The cytotoxic effects of TiO₂ nanoparticles, morphology of cells, bio distribution of nanoparticles under UVA and dark conditions were observed by tem.

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