Toxicity of fluoride to microbial activity and population in soil

The fluoride contamination in the soil imposes a serious impact on the soil characteristics as it affects the microbial activity and diversity in soil owing to its antimicrobial action. The antimicrobial activity of fluoride is mainly mediated by, (1) enzyme inhibition, (2) alteration of proton transfer via cell membranes, and (3) inhibition of biochemical processes in the microorganisms. The main sources of fluoride contamination in the soil are industrial discharge, weathering of rocks, and atmospheric deposition. Soil microorganisms play a very important role in the mineralization process and thus help in nutrient recycling during biogeochemical cycles. The mineralization of organic matter to nutrients by microorganisms is metabolism-dependent so the alteration of the activity of key enzymes by the fluoride changes the microbial diversity of soil. The microbial enzyme activity is highly susceptible to change in environmental factors and is therefore considered the most used parameter for soil pollution studies.