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Rezumat articol ediţie STUDIA UNIVERSITATIS BABEŞ-BOLYAI
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Rezumat: Toxic levels of heavy metals pose a significant threat on living cells, triggering metabolic strategies that help in adaptation to heavy metal-induced stress. We explored the mechanisms assisting the silver resistance in the extremely halophilic archaeon Halomicrobium mukohataei DSM 12286. The modulatory effects of AgNO3 on the cellular antioxidant systems were assessed by evaluating the malondialdehyde levels, the catalase activity, and the total antioxidant, non-enzymatic capacity. Biosynthesized silver nanoparticles were characterized using UV-VIS spectroscopy, bright-field microscopy, transmission and scanning electron microscopy, energy-dispersive X-ray spectroscopy, dynamic light scattering, and the zeta potential measurement. Additionally, bioinformatic approaches were used to infer putative Cu/Ag-transporters that might mediate the evidenced intracellular accumulation of silver nanoparticles. H. mukohataei was seemingly able to mitigate Ag-induced oxidative stress mainly by using non-enzymatic cellular antioxidants. Additionally, we noted the synthesis of spherical and electrically stable intracellular nanoparticles, with sizes ranging from 20 to 100 nm. It was further speculated that active Ag-resistance in H. mukohataei could be achieved through Ag+ uptake by PIB type ATPases followed by accumulation of silver in its colloidal form. To the best of our knowledge, the present work is the first documentation of intracellular silver accumulation in halophilic Archaea, thus broadening current knowledge on heavy-metal resistance in salt-loving microbes, with implications for their potential uses in biomining or bioremediation strategies.
Keywords: bioremediation, Halomicrobium, oxidative stress, silver resistance. |
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