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Title: Cytotoxicity of TiO{sub 2} nanoparticles towards freshwater sediment microorganisms at low exposure concentrations

There is a persistent need to assess the effects of TiO{sub 2} nanoparticles on the aquatic ecosystem owing to their increasing usage in consumer products and risk of environmental release. The current study is focused on TiO{sub 2} nanoparticle-induced acute toxicity at sub-ppm level (≤1 ppm) on the three different freshwater sediment bacterial isolates and their consortium under two different irradiation (visible light and dark) conditions. The consortium of the bacterial isolates was found to be less affected by the exposure to the nanoparticles compared to the individual cells. The oxidative stress contributed considerably towards the cytotoxicity under both light and dark conditions. A statistically significant increase in membrane permeability was noted under the dark conditions as compared to the light conditions. The optical and fluorescence microscopic images showed aggregation and chain formation of the bacterial cells, when exposed to the nanoparticles. The electron microscopic (SEM, TEM) observations suggested considerable damage of cells and bio-uptake of nanoparticles. The exopolysaccrides (EPS) production and biofilm formation were noted to increase in the presence of the nanoparticles, and expression of the key genes involved in biofilm formation was studied by RT-PCR. - Highlights: • Toxicity of NPs towards freshwater sediment bacteria at sub-ppmmore » concentrations. • Decreased toxicity of the nanoparticles in the consortium of microorganisms. • Enhanced bacterial resistance through EPS and biofilm formation in the presence of NPs. • Considerable surface damage of cells and internalization of NPs. • Gene expression analyses related to biofilm formation in the presence of NPs.« less
Authors:
; ; ; ;  [1] ;  [2] ; ;  [1] ;  [2] ;  [3] ;  [4] ;  [1] ;  [5] ;  [1]
  1. Centre for Nanobiotechnology, VIT University, Vellore 632014 (India)
  2. Department of Materials Engineering, Indian Institute of Science, Bangalore (India)
  3. (South Africa)
  4. School of Bio Sciences and Technology, VIT University, Vellore (India)
  5. Department of Chemical Engineering, IIT Madras, Chennai (India)
Publication Date:
OSTI Identifier:
22447558
Resource Type:
Journal Article
Resource Relation:
Journal Name: Environmental Research; Journal Volume: 135; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; ABUNDANCE; AQUATIC ECOSYSTEMS; BACTERIA; COMPARATIVE EVALUATIONS; CONCENTRATION RATIO; DAMAGE; ECOLOGICAL CONCENTRATION; ELECTRONS; FLUORESCENCE; FRESH WATER; GENES; NANOPARTICLES; OXIDATION; POLYMERASE CHAIN REACTION; SCANNING ELECTRON MICROSCOPY; SEDIMENTS; TITANIUM OXIDES; TOXICITY; TRANSMISSION ELECTRON MICROSCOPY; VISIBLE RADIATION