Journal
JOURNAL OF HAZARDOUS MATERIALS
Volume 381, Issue -, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.jhazmat.2019.121226
Keywords
Yarrowia lipolytica; Uranium; Biosorption; Reactive oxygen species; Biomineralization
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Funding
- University Grants Commission under University for Potential Excellence (UPE) Phase II
- SPPU-BARC collaborative Ph.D. Programme
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A marine yeast, Yarrowia lipolytica, was evaluated for morphological, physiological and biochemical responses towards uranium (U) exposure at pH 7.5. The yeast revealed biphasic U binding - a rapid biosorption resulting in similar to 35% U binding within 15-30 min followed by a slow biomineralization process, binding up to similar to 45.5% U by 24 h on exposure to 50 mu M of uranyl carbonate. Scanning electron microscopy coupled with Energy Dispersive X-ray spectroscopy analysis of 24 h U challenged cells revealed the deposition of uranyl precipitates due to biomineralization. The loss of intracellular structures together with surface and subcellular localization of uranyl precipitates in 24 h U exposed cells were visualized by transmission electron microscopy. Cells treated with 50 mu M U exhibited membrane permeabilization which was higher at 200 mu M U. Enhanced reactive oxygen species (ROS) accumulation and lipid peroxidation, transient RNA degradation and protein oxidation were observed in U exposed cells. High superoxide dismutase levels coupled with uranium binding and bioprecipitation possibly helped in counteracting U stress in 50 mu M U treated cells. Resistance to U toxicity apparently developed under prolonged uranyl (50 mu M) incubations. However, cells could not cope up with toxicity at 200 mu M U due to impairment of resistance mechanisms.
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