Research Activities

  • Monitoring Mycotoxin Contamination in Mississippi

    Overall Objective: Aspergillus flavus Using the Agilent 6460 Series Triple Quadrupole LC/MS System, we plan to expand our total aflatoxin monitoring to include individual AFB1, AFB2, AFG1, AFG2 detection, as well as fumonisins, ochratoxins, deoxynivalenol, and zearalenone. Understanding the production of the individual aflatoxins and the presence of the other mycotoxins when coupled to geo-referenced weather and soil conditions, as well as agronomical practices, will allow scientists to better understand the complex host-pathogen interaction, and perhaps develop a conceptual model to predict the occurrence of emerging toxins.

  • Identification of Factors Involved in Degradation or Sequestering of Aflatoxin to Reduce the Economic Impact

    Alumina silicate sequestering agent Using an interdisciplinary approach and keeping with ideologies of the Multistate Research Project, S1033, "Control of Food-Borne Pathogens in Pre- and Post-Harvest Environments" we propose to evaluate the biological degradation of aflatoxin, by Aspergilli, as well as investigate the use of binders to sequester aflatoxin in fermented corn products. Our objective is two-fold: first, to investigate and define the proteome, as well as the associated genes of selected stains involved in the degradation or modification of aflatoxins and second, to adapt theses selected cultures to the industrial ethanol fermentation process and asses the utility of binders in order to lower mycotoxin concentrations in the byproduct, distiller’s grain, important for livestock feed.

  • Decreasing The Impact Of Aflatoxin On Corn And Distillers Grains

    Objectives: SPME coupled to GC/MS In an effort to reduce mycotoxin contamination we will continue to use a proteomic approach to identify proteins involved in the aflatoxin degradation phenomenon. We will screen a variety of clay like materials to determine mycotoxin-binding efficacy. Using a volatile profile library for several species of Aspergilli we will use SPME-GC/MS coupled to Arc-GIS mapping to allow for rapid fungal detection in fields, as well as provide information on the complex host pathogen relationship.

  • Oxidative Remediation Of Aflatoxin-Contaminated Corn

    Contaminated corn Progress has been made towards minimizing the occurrence of aflatoxin in corn through improved farming practices and development of new corn lines; however, contamination remains a significant problem, especially in growing seasons coinciding with drought. Therefore, our team will target two priority areas: amelioration technology for aflatoxin contaminated grain and improved testing procedures. In terms of effective aflatoxin amelioration methods, two approaches will be evaluated. First, chemical oxidative treatments have been shown to degrade aflatoxins in corn and other crops very rapidly. Our research will focus on the efficacy of using ozone to treat harvested corn with the goal of eliminating the presence of aflatoxin while salvaging the inherent nutritive value of the grain.

  • A Maize (Zea mays) Line Resistant to Herbivory Constitutively Releases (E)-β-Caryophyllene

    Fall armyworm Maize is an important US agricultural crop is often destroyed by insect feeding. Maize generates a variety of responses to pest attack, from activation of wound-response pathways such as jasmonic acid (JA) biosynthesis to the release of volatile compounds. Mp708 is an inbred line resistant to feeding by fall armyworm (FAW). The underlying resistance mechanisms are not completely understood. Mp708 has been shown to constitutively express JA and other octadecanoid compounds prior to infestation. Tx601, a genotype susceptible to FAW, activates JA pathway only in response to feeding, suggesting Mp708 is “primed” for attack. Analysis of the volatiles released by the resistant and susceptible lines was conducted using SPME-GC/MS. We have demonstrated the presence of (E)-β-caryophyllene commonly associated with resistance, released constitutively in Mp708. FAW larvae show a preference for Tx601 over Mp708 whorl tissue. Identifying volatiles correlated with resistance could lead to the integration of these traits into commercial varieties.

  • Rapid Identification of Soybean Fungi by Spectroscopic Techniques

    Objectives: M. phaseolina grown on PDA after 5-day growth In an effort to reduce soybean crop losses, we will develop spectrometric techniques that will be able to identify specific types of fungi in field samples. We will explore MALDI-TOF, Microscope FT-IR and Microscope Raman Spectroscopy. The best technology will be selected and spectral libraries will be generated for these identifications. Field personnel will be trained on its use. With the use of the generated data, county agents could minimize crop losses.

  • Imported Catfish and Food Safety
    Objectives: In order to protect Mississippi’s interest in farm raised catfish production, we propose the following: Agilent 6460 Triple Quadripole Mass Spectrometer with 1290 Infinity HPLC
    1. Develop analytical methods for the detection of antimicrobial, drug residues, and environmental chemicals in imported “catfish” by LC/MS/MS including, but not limited to [Andersen, 2004; FDA, 2008; McCord, 2009]:
      • Malachite Green – a fish egg fertilizer used in Asia that is a known carcinogen
      • Crystal Violet – Fish disinfectant used in Asia that is a known carcinogen
      • Chloramphenicol – Antimicrobial agent used in Asian markets that can cause leukemia
      • Fluoroquinolone Antibiotics – Used to treat infections in fish but can result in diminished function when accumulated in human diets
      • Nitrofuran – Antimicrobial agent known to cause birth defects in human fetuses.
    2. Test for Salmonella in imported “catfish” using Real Time Polymerase Chain Reaction (RT-PCR). Salmonella is the most important microbiological pathogen associated with imported “catfish”.
    3. Development and comparison of genomic methods, protein fingerprinting and lipid profiling to identify “catfish” species. Some of the imported “catfish” are not American catfish at all. They are basa, tra, swai, etc. These species are found in Southeast Asia. They are heavily raised as a food source in these countries. Furthermore, they have been sold as American catfish in this country. The methods that will be investigated will be PCR and RT-PCR, Matrix-Assisted Laser Desorption Ionization (MALDI-TOF), and Gas Chromatography with Mass Spectrometry (GC/MS). The comparison of these identification methods is essential to investigate which is best suited for a regulatory setting.
  • Isolation of cellulolytic organisms in the gastrointestinal tract of the giant panda and their potential use in the generation of lignocellulosic-based biofuels

    Candace Williams, Ashli Brown, Carrie Vance, Foping Nature Reserve, China, examining wild panda fecal Lignocellulosic biomass is a renewable resource that can be used for biofuel production with the assistance of cellulolytic anaerobic organisms from fecal material. The ability of fecal material to degrade was shown by the treatment of biomass with giant panda (Ailuropoda melanoleuca) feces, indicating that gut flora may reduce biomass. In our study, eight bacterial groups were enumerated monthly over a fourteen-month sampling of the giant pandas to characterize the gastrointestinal flora. Colony forming units per gram fecal material for Bacteroides spp. ranged in the male and female panda from 102 to 104, values for Clostridium spp. ranged from 102 to 105. The previously unidentified Bacteroides spp. in the giant panda and Clostridium spp. may be useful in the degradation of lignocellulosic biomass and its conversion to biofuels. Further work must be conducted to identify species and to isolate cellulase genes in these organisms; metagenomic work is underway to accomplish these tasks.

  • Microbial Flora of the Giant Panda (Ailuropoda melanoleuca) Digestive Tract

    Le Le, Memphis Zoo Traditional culturing methods were used to identify and characterize normal micro flora in the gastrointestinal tract of the giant panda, Ailuropoda melanoleuca. Fecal samples of an adult male and female giant panda housed at the Memphis Zoo will be collected and will continue to be collected for a twelve month period, and samples were processed to determine the nature of the intestinal bacterial flora. This determination is achieved by both sample storage and processing in anaerobic atmospheres. Once processed, samples are plated on eight different culture medias, four aerobic and four anaerobic, using the Spiral Biotech APC 4000. The eight types of media enumerated eight bacterial groups. The October 2009 results for both male and female giant pandas for total aerobes are 7.90E+08 and 1.69E+08, streptococci are 6.20E+08 and 2.32E+08, total enterics are 4.28E+06 and 6.19E+06, Escherichia coli are 3.20E+06 and 5.73E+06, total anaerobes are 4.00E+03 and 2.07E+04, Clostridium are 1.49E+09 and 6.04E+09, Bacteriodes are <2.00E +03 for both, and Lactobacillus are 5.3E+04 and 5.3E+04, respectively. In addition to fecal samples, information on the bamboo plant parts and dietary supplements the giant pandas are consuming were gathered. Monitoring the flux of the bacterial populations of both male and female giant pandas and the change of their dietary choices will provide the first reported comprehensive profile of giant panda’s intestinal microbial populations following dietary shifts.