Effects of process conditions and yeast extract on the synthesis of selenium nanoparticles by a novel indigenous isolate
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ORIGINAL PAPER
Effects of process conditions and yeast extract on the synthesis of selenium nanoparticles by a novel indigenous isolate Bacillus sp. EKT1 and characterization of nanoparticles Fikriye Alev Akçay1 · Ayşe Avcı1 Received: 23 April 2020 / Revised: 28 May 2020 / Accepted: 4 June 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Selenium nanoparticles (SeNPs) are attractive nanomaterials for application in medical diagnosis, because their toxicities are lower than the elemental selenium which is a functional element and essential for human. In the current study, SeNPs synthesis capability of a novel soil originated indigenous Bacillus isolate was investigated. In this context, effects of processing conditions (SeO2 concentration, pH, temperature, and time), and yeast extract supplementation on the synthesis of SeNPs have been tested. In addition, nanoparticles were characterized and antioxidant capacity was determined. The cell-free supernatant of the bacterium, which was obtained after the cultivation of the isolate in nutrient broth at 33 °C for 24 h, was used for the synthesis. During the synthesis color change from light yellow to red–orange was an indication of the formation of SeNPs. Effect of S eO2 concentration was tested on the formation of nanoparticles and at concentrations higher than 10 mM, there was no formation of nanoparticles. The best production was achieved at 6.4 mM concentration, at pH 9 and 33 °C in 72 h. Field emission scanning electron microscopy (FESEM) images revealed that SeNPs were spherical in shape having the diameters between 31 and 335 nm, and the average diameter was determined to be 126 nm. Energy dispersive X-ray spectroscopy analysis confirmed the presence of elemental selenium. SeNPs possessed significant antioxidant activity that the scavenging capacity was up to 56.5 ± 5% (IC50 322.8 μg/mL). Keywords Selenium · Nanoparticles · Bacillus · Biosynthesis · Yeast extract · Antioxidant
Introduction Nanobiotechnology is the application of microbial biotechnology for the production of nanoparticles (NPs) (Narayanan and Sakthivel 2010). It has attracted a great deal of recent attention, because it is cost effective, environmentally friendly and encompasses the principals of green technology. As chemical and physical synthesis routes of NPs are expensive and utilize toxic reagents, biological synthesis have been proposed as a favorable alternative, especially for nutritional and therapeutic applications (Narayanan and Sakthivel 2010; Thakkar et al. 2010).
Communicated by Erko Stackebrandt. * Ayşe Avcı [email protected] 1
Faculty of Engineering, Department of Food Engineering, Sakarya University, Serdivan, 54050 Sakarya, Turkey
Various bacteria, including strains of the genera Bacillus, Desulfovibrio, Streptomyces, Pseudomanas and Lactobacillus have been reported to synthesize various types of NPs (Sastry et al. 2003; Narayanan and Sakthivel 2010). Bacteria are excellent candidates as biocatalysts because they can easily be cultivated
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