Annual Report 2001

Minutes of Annual Meeting of Southern Regional Information Group-51

Mycotoxins in Foods and Feed Grain

Holiday Inn -- Atlanta Airport North -- January 23, 2001

The meeting was called to order by SRIEG-51 chairman Dr. Bruce Manning at 9:30 am.

Address of venue: Holiday Inn- Atlanta Airport North, 1380 Virginia Ave, Atlanta, GA 30344.

Dr. Manning welcomed everyone to the meeting. He then introduced Dr. O. W. Barnett, the USDA administrative advisor for SRIEG-51, and asked him to make a few comments to the group. Dr. Barnett, commented about the web site for SRIEG-51 which includes the minutes of each annual meeting, keywords, meeting sites, accomplishments, publications, objectives, and list of officers of each state.

State reports were presented:

Dr. David M. Wilson presented information on his research on occurrence of fumonisins and aflatoxins in south Georgia corn from 1996 to 1999. This reseach was presented at a workshop on fumonisins entitled, "Risk Assessment Workshop", in January, 2000. He analyzed corn samples from at least 40 counties for fumonisins (FB1, FB2, and FB3) and aflatoxins (B1, b2, G1, and G2) by HPLC and the VICAM aflatest fluorometer. He found the level of both toxins were very high in some years. Ear damage was correlated with fumonisin and aflatoxin levels and there was a significant positive correlation between fumonisin and aflatoxin contamination. Also, he reported on mycofloral and analysis of pre-harvest southern Georgia corn survey from 1996 to 1999. He found Fusarium species of the Liseola Section and Aspergillus flavus group were the dominant species in most of the samples. He mentioned that fumonisins are found in corn and corn products only(from quoet Dr. D. Miller, Canada). This is not true accorrding to Dr. Abbas, because fumonisins were found in rice and sorghum in various parts of the world. The new publication by Dr. Peter Cotty used the Fg/g (ppm) unit for aflatoxin instead of the traditional ng/g unit (ppb). He and the group agreed that the standard unit ppb for aflatoxin needs to be used in all forms of publication unless there is a good reason to change it. Also, he presented information on immunochemical methods such as VICAM and ELISA for aflatoxin analysis. He thinks that VICAM is approved by AOAC as a quantitative assay method while ELISA is approved by AOAC as a survey method for aflatoxin. He said both methods are expensive to use for research on mapping corn hybrids for resistance to toxins.

Dr. N. W. Widstrom presented his work on aflatoxin contamination in the field in Georgia. He has 24 years of data for at least 40 counties in south Georgia. In only 2 years out of 24 was the level of aflatoxin below 20 ppb. Early planting appears to increase the aflatoxin contamination. Neither Aspergillus or Fusarium spp are dominant, even though they were inoculated or sprayed at different levels.

The economic impact of raising corn was also discussed. Insect damage also seems to increase aflatoxin contamination. Corn with high levels of maysin, a phytoalexin, shows resistance to both insect damage and aflatoxin contamination.

Mapping of chromosomes was done to locate genes that were responsible for maysin, silk antibiosis and husk tightness. Markers were isolated to enhance genetic resistance to ear-feeding insects and aflatoxin contamination. Markers, gene mapping and maysin research have been done by Dr. B. Z. Guo.

Dr. Robert Brown presented information on his research on identification of proteins that have properties to effect the growth of Aspergillus flavus and production of aflatoxins. He presented information on wax materials isolated from corn that show activity against the Aspergillus flavus and aflatoxin production. The wax materials were identified by TLC plates. The active band contained 3 compounds by GC/MS. He said more work was needed to identify the chemistry of these compounds. Two African corn lines have been identified that show resistance to Aspergillus by increasing the growth of the fungus and decreasing the production of aflatoxin by inhibiting the biosynthetic pathway of the toxin. More reseach is needed to determine exactly the mechanism of resistance. He said that he needs to obtain permission in order to release the hybrids for other locations.

Dr. Ken E. Damann reported that the herbicide Liberty can be used to affect the growth of Aspergillus flavus and aflatoxin production in the laboratory and field. When this herbicide was added to fungal media and to kernal screening assays, it reduced growth of the fungus. He thinks this is because this herbicide generates NH3 which is the active agent. When the herbicide is sprayed on corn plants 40 day and 60 days after midsilking, the levels of aflatoxin were reduced by 75%.

Dr. Rick Mascagni presented information on the influence of irrigation, hybrid, and seeding rates on corn yields and on aflatoxin accumulation. He found no differences in aflatoxin levels among the treatments, while there was a signficant difference with levels of fumonisins and moisture deficits. Levels of fumonisins were increased with increase in moisture.

Dr. Steven Moore presented his research on using fluorescence (Black Light) to pre-screen individual corn ears for their resistance to aflatoxin. He used 205 ears for this study. Two populations were inoculated and rated for fungal growth, fluorescences, and aflatoxin levels. A rating of 0 to 9 was used to rate fungal growth and fluorescence with 0 equal to none and 9 equal to most severe. He found that the rating of 2 seems useful as a pre-screening tool and should reasonably identify the ears with lowest aflatoxin level in a segregated population. He emphasized that this conclusion is not meant to justify the rountine use of fluoresesence to measure aflatoxin levels in corn. Using a fluorescence rating of 2 as a pre-screening tool could reduce the number of ears requiring testing for aflatoxin level by 80% or more. Screening at a fluorescence rating of 2 will allow a third or more ears to be tested which exceed 100 ppb aflatoxin. Screening at a fluorescence rating of 2 may result in culling about 2% of ears with aflatoxin levels below 100 ppb.

MISSISSIPPI:

Dr. H. K. Abbas presented information on his project which is control of aflatoxin and fumonisin levels in corn in the Delta by studying the role of the agricultural practices and fungal ecology. He presented data on co-occurrence of aflatoxin (B1 & B2), fumonisin (FB1, FB2, FB3, FB4, and FC4) and DON in corn in the Mississippi Delta. Toxin levels were very high in the 1998 test and higher than in 1999. Mycotoxin determinations were done by ELISA and VICAM and the identity of the toxin was confirmed by TLC plate and mass spectroscopy methods. He presented data of the ecology of Aspergillus flavus in Mississippi delta soils under corn production. He found that the fungal A. flavus isolates were distributed randomly in a 2000 survey with 16 sites with differing cropping histories such as corn, cotton, soybean, sorghum. Also, he found that A. flavus isolates positive for aflatoxin changed color when treated with NH3, but color density did not correspond with levels of aflatoxins. Cultures of A. flavus that did not change color when treated with NH3 were not necessarily negative for production of aflatoxins. These cultures needed testing by other methods to confirm their capacity for aflatoxin production.

Dr. Gary Windham presented data on their project which is screening aflatoxin resistant corn hybrids grown in the field at Mississippi State, Starkville, in 1998. Also, he presented data on a multilocation evalution of single cross cron hybrids for aflatoxin contamination to test the stability of resistance under various locations. These locations included Stoneville, MS; St. Joseph, LA; Starkville, MS; Tifton, GA; and Weslaco-TX.

Dr. Bruce Manning presented information on his research on the effect of various mycotoxins on channel catfish. He found that T-2 toxin is more toxic to channel catfish than deoxynivalenol (DON), aflatoxins, and fumonisins.

DISCUSSION ON THE OBJECTIVES AND PRIORITIES OF SRIEG-51

Called to order by Dr. B. Manning at 3:30 p.m., January 23, 2001.

There was discussion about the objective of this group. Since this is an information exchange group, objectives are not required. However, Dr. Barnett stated that we have prepared written objectives in the past and he read them to the group: 1) To exchange information and coordinate efforts to identify and develop germplasm with resistance to contamination by mycotoxins, to devise improved agronomic practices and sanitation procedures during product storage and processing. 2) To exchange information regarding the mode of action of significant acute and chronic effects of mycotoxins on domestic animals and human health. 3) To exchange information on epidemiology, biochemistry, physiology, and molecular biology of toxigenic fungi and mycotoxins as they relate to the environment unique to the Southern U. S. and 4) To exchange information on the yearly extent of mycotoxins and toxigenic fungi in food and feed grains, and the development of efficient economical analytical methods for assessment of mycotoxins.

There was discussion about these objectives which included rewriting them to reflect advances in mycotoxin technologys. Dr. B. Z. Guo volunteered to rewrite the objectives with help from Dr. D. Wilson. They will distribute the first draft to members who attended the meeting for their comments and input before it is prepared in a final document.

Treasurer=s report: Dr. H. K. Abbas gave the report. The bank account for SRIEG-51 is maintained at First Liberty Bank, Georgia. Current balance on Dec. 29, 2000 was $546.34. The account has had a service charge of $6.00 a month. Since I got the first statement when I became treasurer, I decided to close the account and find a bank to keep our money without a service charge. Expenditures for this meeting, January 23, 2001, were $648.57 for meeting room rental, visual equipment, and refreshments at Holiday Inn Airport North, Atlanta, GA, and plus $50.00 for supplies, postage, and typing services . Registration of this meeting was $40.00 and we earned $440.00 from 11 people in attendance. After the expenditures were paid for this meeting, the final account balance was $282.23. Treasurer=s report was approved and accepted.

Election of new officers: Dr. B. Z. Guo was elected secretary-treasurer for year 2001. Also, it was discussed that the mailing list needed to be updated and names of inactive members deleted. Dr. Rick Mascagui will advance to 2001 chair and Dr. H. K. Abbas will be vice-chair.

Chair:  Bruce Manning, National Warmwater Aquaculture Center, P. O. Box 197, Stoneville, MS 38776

Vice-Chair:  Rick Mascagni, Northeast Res. Sta. P. O. Box 438 St. Joseph, LA 71366

Secretary Treasurer: Hamed K. Abbas, UDSA-ARS, Crop Genetics & Production Research Unit,
   141 Experiment    Station Rd, .P. O. Box 345, Stoneville, MS 38776

Administrative Advisor:  O. W. Barnett, North Carolina State University, Department of Plant Pathology    Box 7616, 2518 Gardner Hall, Raleigh, NC 27695-7616

Past Chair:  Gary Windham, USDA, ARS, CSRL, P. O. Box 5367 Mississippi State University
   Mississippi State, MS 39762

Next Meeting Site:  Alexandria, LA 2002