title: Cytotoxicity of TiO2 nanoparticles towards freshwater sediment microorganisms at low exposure concentrations.
abstract: There is a persistent need to assess the effects of TiO2 nanoparticles on the aquatic ecosystem owing to their increasing usage in consumer products and risk of environmental release. The current study is focused on TiO2 nanoparticle-induced acute toxicity at sub-ppm level (≤1ppm) 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.
authors.affiliation: Centre for Nanobiotechnology, VIT University, Vellore 632014, India.
authors.forename: Jyoti
authors.initials: J
authors.lastname: Kumari
authors.affiliation: Centre for Nanobiotechnology, VIT University, Vellore 632014, India.
authors.forename: Deepak
authors.initials: D
authors.lastname: Kumar
authors.affiliation: Centre for Nanobiotechnology, VIT University, Vellore 632014, India.
authors.forename: Ankita
authors.initials: A
authors.lastname: Mathur
authors.affiliation: Centre for Nanobiotechnology, VIT University, Vellore 632014, India.
authors.forename: Arif
authors.initials: A
authors.lastname: Naseer
authors.affiliation: Centre for Nanobiotechnology, VIT University, Vellore 632014, India.
authors.forename: Ravi Ranjan
authors.initials: RR
authors.lastname: Kumar
authors.affiliation: Department of Materials Engineering, Indian Institute of Science, Bangalore, India.
authors.forename: Prathna
authors.initials: P
authors.lastname: Thanjavur Chandrasekaran
authors.affiliation: Centre for Nanobiotechnology, VIT University, Vellore 632014, India.
authors.forename: Gouri
authors.initials: G
authors.lastname: Chaudhuri
authors.affiliation: Centre for Nanobiotechnology, VIT University, Vellore 632014, India.
authors.forename: Mrudula
authors.initials: M
authors.lastname: Pulimi
authors.affiliation: Department of Materials Engineering, Indian Institute of Science, Bangalore, India; Department of Chemical Technology, University of Johannesburg, South Africa.
authors.forename: Ashok M
authors.initials: AM
authors.lastname: Raichur
authors.affiliation: School of Bio Sciences and Technology, VIT University, Vellore, India.
authors.forename: S
authors.initials: S
authors.lastname: Babu
authors.affiliation: Centre for Nanobiotechnology, VIT University, Vellore 632014, India.
authors.forename: Natarajan
authors.initials: N
authors.lastname: Chandrasekaran
authors.affiliation: Department of Chemical Engineering, IIT Madras, Chennai, India.
authors.forename: R
authors.initials: R
authors.lastname: Nagarajan
authors.affiliation: Centre for Nanobiotechnology, VIT University, Vellore 632014, India. Electronic address: amit.mookerjea@gmail.com.
authors.forename: Amitava
authors.initials: A
authors.lastname: Mukherjee
mesh_terms: D000704:Analysis of Variance; D001419:Bacteria / Q000187:drug effects*; D018441:Biofilms / Q000187:drug effects; D002463:Cell Membrane Permeability / Q000187:drug effects; D017931:DNA Primers / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D019015:Geologic Sediments / Q000382:microbiology*; D007194:India; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D060106:Lakes / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000032:analysis / Q000633:toxicity*; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D010316:Particle Size; D017382:Reactive Oxygen Species / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013482:Superoxide Dismutase / Q000378:metabolism; D014025:Titanium / Q000032:analysis / Q000633:toxicity*; D023382:Toxicity Tests, Acute / Q000379:methods
chemical_list: D017931:DNA Primers; D017382:Reactive Oxygen Species; C009495:titanium dioxide; D014025:Titanium; D007770:L-Lactate Dehydrogenase; D013482:Superoxide Dismutase
keywords: Bacteria; Consortium; TiO(2) NPs; Visible light and dark conditions