Biosynthesis of Nano-Selenium and Its Impact on Germination of Wheat under Salt Stress for Sustainable Production

Abstract

Selenium and its derivatives have been found capable of excellent biological responses. However, the element in its bulk form has low bioavailability and increased toxicity, meaning the production of effective forms with sustainable methods has become urgent. Several microorganisms, including fungi, bacteria and yeast, as well as higher plants, are capable of biosynthesizing nanoparticles such as nano-selenium (nano-Se), which has wide applications in medicine, agriculture and industry. Thus, the biosynthesis of nano-Se using some bacterial species was the main target of this study. The production of nano-Se and the monitoring of its impact on the wheat germination of seeds under salt stress (i.e., 50, 100, and 150 mM NaCl) was also evaluated in the current study. The ameliorative role of nano-Se doses (i.e., 50, 75, and 100 mg L−1) in the germination of wheat seeds under salt stress was also investigated. Based on sodium selenite tolerance and reducing selenite to elemental Se-NPs, the most effective isolate (TAH) was selected for identification using the 16S rRNA gene sequence, which belonged to Bacillus cereus TAH. The final germination percent, mean germination time, vigor index and germination rate index were improved by 25, 25, 39.4 and 11%, respectively, under 15 mM sodium chloride concentration when 100 mg L−1 nano-selenium was used. On the other hand, the results obtained from a gnotobiotic sand system reveal that with treatment with 100 mg L−1 nano-selenium under high Ec values of 14 ds m−1, the vegetative growth parameters of shoot length, root length, fresh weight and dry weight were improved by 22.8, 24.9, 19.2 and 20%, respectively, over untreated controls. The data obtained from this study reveal that the use of nano-selenium produced by Bacillus cereus offers improved wheat seed germination under a salt-affected environment.