Mitigation of Arsenic Accumulation in Crop Plants Using Biofertilizer

Abstract

Abstract Elevated levels of arsenic in crop plants have been found in various regions worldwide, especially where agricultural soils have been affected by arsenic-enriched aquifer and human activities including mining, smelting, pesticide application, and so forth. Given the highly toxic nature of arsenic, remediation should be carried out immediately to reduce this potentially toxic element transport from soil to crop plants. This study focused on the utilization of biofertilizer which is a combination of arsenic-accumulating microorganisms and adsorbent (carrier) in order to achieve high efficiency of arsenic immobilization and ability to apply in the field. Thirty-two bacterial strains were isolated from 9 soil samples collected from Dongjin and Duckum mining areas in Korea using nutrient medium amended with 2 mM sodium arsenite. Among isolates, strain DE12 identified as Bacillus megaterium exhibited the greatest arsenic accumulation capacity (0.236 mg/g dry biomass) and ability to resist up to 18 mM arsenite. Among three agricultural waste adsorbents studied, rice straw was proved to have higher adsorption capacity (0.104 mg/g) than rice husk and corn husk. Therefore, rice straw was chosen to be the carrier to form biofertilizer together with strain DE12. Inoculation of biofertilizer in soil showed reduction of arsenic content in edible part of lettuce, water spinach, and sweet basil by 17.5%, 34.1%, and 34,1%, respectively compared to control group. The use of biofertilizer may open up the potential application in the field for other food plants.