Bioremediation Potential of Fleurya aestuans (West Indian Wood Nettle) Assisted by Fungi in Heavy Metal-contaminated Soil

Abstract

Heavy metal contaminated soil caused by pesticides, industrial pollution, and atmospheric deposition has harmful impact on the environment, posing a risk to human health, and affecting food safety. Physiochemical and convective methods to remediate contaminated soil are often costly and harmful to the environment, but plant extraction is an important alternative cost-effective and eco-friendly method. This study investigated the potential of Fleurya aestuans and fungi to bioaccumulate selected heavy metals from simulated soil. Soil analysis was performed in parts per million (ppm) before adding heavy metals to samples and F. aestuans was grown on 15 soil samples collected from Chrisland University, each weighing 5.5 kg. Three replicates of soil samples contaminated with 10g/kg of cadmium (Cd), copper (Cu), lead (Pb) and composite of all heavy metals (Ahm) were simulated, and used to evaluate the extraction capacity of F. aestuans. Three control experiments were also performed without contaminating soil samples with heavy metals. Fungi and yeasts were isolated from soil samples simulated with Pb, Cu, Cd, Ahm, and controls, and screened to determine their tolerance to heavy metals selected by spectrophotometry. Aspergillus niger II was identified as the most tolerant fungal isolate and was used as a bioremediator. After harvest, the concentration of tested heavy metals in roots, shoots and soil samples were detected to recognize the bioaccumulation capability. Duncan’s multiple range test was followed to analyze the obtained data. The results indicated significant variation in the metal uptake across treatments. Cd recorded the highest concentration in the root and shoot of F. aestuans grown on Cd simulated soil with A. niger. This study shows that F. aestuans in conjunction with Aspergillus had a mutual association in bioaccumulating Pb and Cu. As a result, the selected plant was found a good bioaccumulator for heavy metal extracted from contaminated soils.