Cadmium Toxicity and Tolerance in Micro- and Phytobiomes

Abstract

Heavy metals, such as Cd, are contaminating soil and water bodies. Toxicity of Cd retards the growth of microbes and plants. The entry of Cd into the cells occurs through transition metal transporters. Diminished cellular micronutrient stores, and a decrease in the activity of enzymes such as dehydrogenases, alkaline phosphatases, and so forth, are the immediate toxic effect of Cd on microbes. Green plants experience oxidative stress upon Cd exposure. The deleterious effects of Cd retard photosynthesis and biomass productivity in plants. However, there are Cd defense mechanisms in plants. These mechanisms are root exudation, Cd exclusion, and speciation of Cd with carboxylic acids, or metal binding peptides such as phytochelatins. Cadmium stress on bacteria and plants has ecological impacts, such as inhibition of organic matter decomposition and loss of biodiversity, respectively. Ecological assessment of Cd toxicity also helps determine Cd-tolerant plant species that can be used in the ecofriendly cleanup of Cd in the environment.