Abstract
This study is aimed to explore the toxicity of TiO2 nanoparticles at low concentrations (0.25, 0.50 & 1.00 μg/ml); on five bacterial isolates and their consortium in waste water medium both in dark and UVA conditions. To critically examine the toxic effects of nanoparticles and the response mechanism(s) offered by microbes, several aspects were monitored viz. cell viability, ROS generation, SOD activity, membrane permeability, EPS release and biofilm formation. A dose and time dependent loss in viability was observed for treated isolates and the consortium. At the highest dose, after 24h, oxidative stress was examined which conclusively showed more ROS generation & cell permeability and less SOD activity in single isolates as compared to the consortium. As a defense mechanism, EPS release was enhanced in case of the consortium against the single isolates, and was observed to be dose dependent. Similar results were noticed for biofilm formation, which substantially increased at highest dose of nanoparticle exposure. Concluding, the consortium showed more resistance against the toxic effects of the TiO2 nanoparticles compared to the individual isolates.
Highlights
IntroductionTiO2-NPs are an important component of paints, sunscreens, food additives and coloring compounds and are used for ground water remediation [1]
Nano-scale particles are found naturally in the environment
The present study provides a holistic understanding on the behavior and interactions of individual isolates and the consortium in waste water medium in presence of TiO2-NPs at low concentrations under dark and UVA condition
Summary
TiO2-NPs are an important component of paints, sunscreens, food additives and coloring compounds and are used for ground water remediation [1]. TiO2-NPs has the highest production rate estimated around 5000 tonns till 2010 and is predicted to increase up to 2.5 million tons by 2025 [2]. The concentration of Ti4+ ions has been estimated to be 181–1233 μg/ml in waste water treatment plants [6, 7]. The dynamic processes such as the discharge of nanaoparticles, through product degradation, waste water effluents, sludge and other routes affect the PLOS ONE | DOI:10.1371/journal.pone.0141301. The dynamic processes such as the discharge of nanaoparticles, through product degradation, waste water effluents, sludge and other routes affect the PLOS ONE | DOI:10.1371/journal.pone.0141301 October 23, 2015
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