ABSTRACT
For years, there has been discussion of a minor line between the amount of selenium that is necessary and its toxic dose. When it comes to selenium as an important nutritional factor in health or disease, we inevitably have to address its cycle in nature, which affects by volcanic mountains, seasonal rains, water evaporation, all kinds of living existences, microorganisms and insecticides, waste of vertebrates, and fertilizers. If selenium in the soil in which plants are grown is high, it will cause selenium accumulation in the plant and its consumption will be harmful to the next consumer in the selenium cycle. On the one hand, high selenium easily replaces sulfur in the chemical structure of protein molecules and causes disease, but on the other hand, it plays an effective biological role, e.g. immunogenesis at the right dose. Selenium can prevent the growth of pathogens in plants and the consequent spoilage of agricultural products. Selenium, in nanometer dimensions, shows more significant biological properties, especially if it is produced biologically introducing no harmful substances to nature during its synthesis process. With the potential of genetic engineering and the possibility of designing the chromosomes of Saccharomyces cerevisiae, it is possible to fully trace and understand the mechanisms involved in all stages of the production process of selenium nanoparticles. We hope that this approach to the biological production of nanoparticles could be extended to genetic engineering for massive biosynthesis to make it possible for the production of selenium in required amounts for living organisms.
