Does the Presence of the Arsenic Hyperaccumulator, Pteris Vittata, Modulate Impact of Arsenic on Enzyme Activity in Contaminated Soil?.

Arsenic is a metalloid prevalent in the environment, and a known as carcinogen. Its concentration is generally low in the environment but readily increased by anthropogenic activities such as agricultural chemical use, mining, industrial waste, etc. Over 41% of the superfunds sites in the US are reportedly contaminated with arsenic. Pteris vittata has been identified as an arsenic hyperaccumulator with a potential for use in bioremediation of arsenic contaminated environment. Pteris vittata is known to produce root exudates, which may influence arsenic bioavailability, hence, its effects on the microbial community structure and enzyme activity in its rhizosphere. These not only affect critical enzymes and microbial community crucial to the biogeochemical processes taking place in the soil, but also impact nutrient cycling and uptake. It is important therefore to understand the Pteris vittata rhizosphere enzymatic dynamics, critical to nutrient cycling and availability to the plant, and its subsequent utilization in a successful bioremediation strategy. In this study, enzymes activity was evaluated in rhizosphere and non-rhizosphere soils of hyperaccumulator, Pteris vittata, spiked with different concentration (0, 50, 100, 150, 200, and 500 mg kg^-1 soil) of arsenic. Nitrogen-, carbon-, and Phosphorus-cycling enzymes activities were quantified from the rhizosphere and non-rhizosphere soils, 89 days post arsenic-spiked soil incubation before planting the hyperaccumulator, Pteris vittata, and on 98 days after planting. Preliminary results showed a significant reduction in phosphatase activities at the 500 mg As kg^-1 soil. Further results would be presented on impact on carbon- and nitrogen-cycling enzymes. Work supported by: USDA-NIFA 1890-CBG funded iBREED project to Tuskegee University Plant Biotech Lab, GWCAES-CAENS.