http://www.nanobe.org Nano Biomed Eng 2017, 9(1): 15-20. doi: 10.5101/nbe.v9i1.p15-20. Research Article 15 Nano Biomed. Eng., 2017,Vol. 9, Iss. 1 The Determination of Biomass/Selenium Ratio and the Impact of Glucose and Piperitone upon Selenium Ion Reduction Using Bacillus sp. MSh-1 Whole Cells Abstract Many bacteria are potential to reduce the metal ions to elemental nanoparticles and are able to grow in the presence of these inorganic compounds. Whole bacterial cells suspended in aqueous media can also convert some soluble metal ions into elemental nanomaterials. In this study, the reduction of different concentrations of selenium ions was investigated using various amounts of Bacillus sp. MSh-1 whole cell biomass, with the aim of increasing the yield of selenium nanoparticles. The MSh- 1 test strain used in this study was previously isolated from the Caspian Sea (north of Iran) which can produce selenium nanoparticles. Reduction of selenium ions by whole Bacillus sp. MSh-1 cells in normal saline had a close relation between the ratio of applied biomass and the selenium ion concentration, as no considerable reduction was detected in the ratios lower than 1 gram of biomass for each 100 mg of selenium. Neither compounds of piperitone nor glucose had positive effects on selenium reduction by Bacillus sp. MSh-1. It also should be mentioned that Se NPs were not effciently produced even after 20 hours and 32 hours, respectively. Keywords: Bacillus; Selenium nanoparticles; Glucose; Piperitone; Reduction Mojtaba Shakibaie 1 , Erfan Kheradmand 2 , Mohammad Hossein Yazdi 2 , Faranak Mavandadnejad 2 , Ruhollah Mirjani 3 , Ahmad Reza Shahverdi 2 1 Herbal and Traditional Medicines Research Center, Kerman University of Medical Sciences, Kerman, Iran. 2 Department of Pharmaceutical Biotechnology and Biotechnology Research Center, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran. 3 Department of Advanced Technologies, Faculty of Medicine, AJA University of Medical Science, Tehran, Iran. Corresponding author. E-mail: shahverd@sina.tums.ac.ir; Tel/Fax: +9864122303. Received: Mar. 6, 2017; Accepted: Mar. 15, 2017; Published: Mar. 20, 2017. Citation: Mojtaba Shakibaie, Erfan Kheradmand, Mohammad Hossein Yazdi, Faranak Mavandadnejad, Ruhollah Mirjani, and Ahmad Reza Shahverdi, The Determination of Biomass/Selenium Ratio and the Impact of Glucose and Piperitone upon Selenium Ion Reduction Using Bacillus sp. MSh-1 Whole Cells. Nano Biomed. Eng., 2017, 9(1): 15-20. DOI: 10.5101/nbe.v9i1.p15-20. Introduction Toxic metals or metalloid ions are reduced to their elemental forms by living organisms as a strategy for decreasing the toxicity of these ions [1, 2]. Metal or metalloid ions are usually secreted as amorphous or crystalline nanomaterials within the intercellular spaces of the living cells [3]. These secreted nanomaterials can be released and separated for experimental use following cell disruption by various physical and chemical methods [4]. Selenium, a vital trace element for both eukaryotes and prokaryotes has broad applications [5]. It is also a micronutrient metalloid with extensive applications [6]. Dietary selenium compounds play an important role in