Selenium in soil-microbe-plant systems: Sources, distribution, toxicity, tolerance, and detoxification

Selenium is an essential micronutrient required for natural biological systems such as anti-oxidative systems. Despite such beneficial aspect, contamination of selenium and its subsequent bioaccumulation can be harmful to environment and human health. In light of the significance of its contamination, various technologies have been developed for the treatment and bioremediation of selenium-laden soil and wastewaters. However, there are still a number of challenges such as establishing its stringent discharge limits, predicting the fate of bio-reduced selenium in the environment, and securing the long-term stability of biogenic selenium. This review highlights the basic factors governing the environmental distribution and behavior of selenium in relation to its sources, speciation, bioavailability, toxicity, and detoxification/tolerance mechanism in microbes and plants. This review is expected to offer valuable insights into the development of effective control options for selenium in the environment.