Selenium Bioavailability Through Microbes

Abstract

Selenium is an important essential trace micronutrient for living systems. Selenium in trace concentrations are essential for the growth and reproduction of plants, animals and microorganisms; however, this essential trace micronutrient element easily become toxic at concentrations higher than the physiological level. Selenium deficiency is regarded as a major health problem for 0.5–1 billion people worldwide. Oxyanions of selenium, viz. selenite and selenate, are bioavailable; selenium in the form of selenate ion (SeO4 2 ) is more toxic to most organisms than selenite (SeO3 2 ). Contrarily, elemental selenium (Se0) is insoluble, less toxic compared to other selenium forms. Nano-Se (Se0) in the range of 100–500 nm has similar bioavailability to other selenium forms into plants, animals, humans and microorganisms. Microbial nano-selenium biosynthesis is an eco-friendly and potentially economically viable ‘green synthesis’ route towards synthesis of red elemental selenium and contributes to the application of selenium for human health. In the soil, applied selenium is rapidly reduced to insoluble forms, and usually the crop nutrient use efficiency was less than 10 % only. Selenium addition in commercial fertilizers may be a larger programme method that is too wasteful, as much of the Se used thereby will be lost for future utilization. Direct addition of selenium compounds to food (process fortification) can be undertaken by the food industry for judicial use of this essential trace micronutrient. Selenium is a non-renewable resource. So it should be a concern of the all stakeholders that the extracted selenium should be judiciously used and to be stockpiled for use as an essential nutrient over generations.