Comparative DNA Analysis of Soils Treated with Pesticides and Poultry Litter

1. Comparative DNA Analysis of Soils Treated with Pesticides and Poultry Litter Alisha Sledge, RakeytaScales, Dr. Elica Moss, & ThiliniRanatunga Faculty Mentor: Dr. Elica Moss, Professor, Department of Natural Resources & Environmental Sciences, Alabama A & M University, Normal, AL 35762 Abstract Results The level of arsenic in the poultry litter applied soil is 7.67 mg/kg and 7.26 mg/kg for the pesticide applied soil. The average pH level for the control sample of cotton field soil is 6.53, pesticide applied soil is 6.8, control sample of poultry litter soil is 7.1, and poultry litter soil is 6.4. This research determines the DNA profiles of soil samples collected from agricultural fields that have been treated with pesticides and/or amended with poultry litter. Conventional crop producers apply inorganic fertilizers and rely on chemical pesticides to control pests including weeds, insects and diseases. For organic producers, the use of poultry litter as mulch and organic fertilizer has become a common practice in the area due to its availability and low cost. Soil samples collected from Huntsville and Sumter County, Alabama contain small amounts of arsenic (arsenate and arsenite). Arsenic is mainly found in pesticides and naturally in rocks and minerals, thus making arsenic prevalent in soil and therefore groundwater. The high levels of arsenic in soil decrease the diversity of microorganisms, which can be used to transform arsenic into arsenite; making it an organic substance. Arsenic is less toxic in the organic state, therefore, when it is oxidized it is easier to adsorb and remove arsenic from the environment. In this preliminary study, the pH was first determined for each of the experimental soils containing pesticides and poultry litter and also the control soils without pesticides or poultry litter additions. The pH levels ranged from 6.3-7. The DNA was then extracted and the significant amounts were determined that differentiated each soil. Further analysis by PCR and sequencing will identify the presence of arseniteoxidase genes in the soil that are responsible for easily removing toxic amounts of arsenic from soil. Introduction Arsenic is a toxic, carcinogenic heavy metal that when released into the environment whether through air, water, or soil can have adverse health effects. It naturally occurs in mineral rocks and soils. In the environment, arsenic cannot be destroyed. Organic arsenic is formed when it combines with carbon and hydrogen in plants and animals. Organic arsenicals are used as “herbicides on agricultural lands, orchards, and golf courses”. High levels of arsenic also impact biodiversity in soils. The higher levels of arsenic in a soil, then the less the diversity of microorganisms in the soil (Cai & Liu, 2009). The health effects that arsenic can cause when released into the environment include respiratory irritation, skin cancer, lung cancer, cardiovascular effects, gastrointestinal damage, and kidney effects exposed either through inhalation, dermal, or ingestion (ATSDR, 2007). Bacteria can be used to transform arsenic into arsenite; making it an organic substance. Poultry litter is used as a source of fertilizer in agricultural practices in Sumter County, Alabama. It is also used in the cotton fields in the pesticide applied soils. Arsenic contamination is a result from land application of poultry litter; therefore, there is a high amount of arsenic levels. Pesticides are used to control the rapid growth of weeds in cotton fields. Unfortunately, these pesticides contain high concentrations of arsenic. Objectives Determine the pH levels for the poultry litter and pesticide applied soils and their controls. Determine the amount of DNA found in poultry litter and pesticide soils and their controls. Identify the levels of arsenate and arsenite in soils. • The pH values of the soils are within the range recommended of 6.3-7 for the pesticide applied and poultry litter soils. • There was not a high level of arsenic in the soils. • There was no difference in DNA concentration between the controls and the amended soils. • For future research, the presence of arsenic oxidase genes will be conducted. Discussion/Conclusion Materials & Methods • Collect samples of pesticide applied soil and poultry litter soil. • Poultry litter and pesticide applied soil extracts was carried out at Frontier Global Science, Inc. inWashington using hydride generation-Cryogenic Trapping (HG-CT-GC-AAS) & Gas chromatography  • Extract DNA from the controlled samples of the pesticide applied and poultry litter soils and the amended pesticide applied and poultry litter soils using MO BIO- PowerSoil DNA Isolation Kit and follow manufacturers’ instructions. • Determine the DNA concentration of each soil type using Nanodrop. I would like to acknowledge the National Science Foundation for providing funding for this research.