Minutes of Annual Meeting of Southern Regional Information Group-51

Mycotoxins in Foods and Feed Grain

New Orleans, Louisiana         January 25-27, 1999

            The joint meeting of SRIEG-51 and NC-129 was convened at 1:00 PM, January 25, 1999 at the Doubletree Hotel in New Orleans by Dr. Gary Windham, Chair SRIEG-51.  There were 38 participants in attendance.  After remarks by Dr. Windham, Dr. D.M. Wilson, Chair of NC-129 was introduced and made additional comments.  The USDA administrative advisors, Dr. O.W. Barnett for SRIEG-51 and Dr. Beverly Durgan for NC-129, were introduced and commented about the current objectives of the two groups.

State reports were presented:

Bruce Manning presented a report on recently completed mycotoxin studies with fish.  Catfish are sensitive to moniliformin at 20 ppm causing significantly reduced growth during a 1-week feeding study and tilapia showed significantly lower growth and higher sphinganine to sphingosine ratios when fed 75 ppm flumonisin B1.

N.W. Widstrom presented information on research with the red kernel marker of the aleurone of corn and Aspergillus flavus infection.  He reported that mean AFB1 levels in corn were 8 ppb in 1997 and greatly increased to 236 ppb in 1998.  He also commented on the greater incidence of A. flavus infection as a result of insect damage and poor rainfall distribution.

Zeliko Jurjevic presented information on the relationship of insect damage to corn kernels and resultant increased A. flavus infection and contamination with AFB1.  Ear damage and correlation with AFB1 and FB1 contamination is 0.583 and 0.417, respectively.  Broken pericarp allows fungal invasion and subsequent growth.  After wound inoculation of A. flavus and F. moniliforme, on corn in moist climate F. moniliforme predominates over A. flavus.

Wellington Mubatanhema reported that in a liquid culture growth of A. flavus,

NRRL 5520, was suppressed by F. moniliforme A. niger and Rhizopus.  Fusarium moniliforme can suppress AFB1 production, but only lasts for several days.  Production of FB1 by F. moniliforme was not evaluated.

Dave Wilson provided an interesting slide presentation on Brazil nut culture in Bolivia and the potential for contamination with AFB1.

LLINOIS

Charles Woloshuk reported that the results of a 1998 survey indicated that corn ear rot and insect damage were very low.  Fumonisin B1 production was influenced by the pH of the medium; low pH of 3.0 to 5.0 provides for good FB1 production, but above pH 7.0 there is no production of FB1.

IOWA

No report.

LOUISIANA

K.E. Damann reported that exposure to BHT prior to inoculation with Aspergillus flavus reduced AFB1 concentration up to 50%.  The herbicide, Liberty, reduced the concentration of aflatoxin by slowing the growth of A. flavus.

MICHIGAN

L.P. Hart gave a report on wheat scab and the application of chemicals to wheat and the effect on vomitoxin concentrations; some increase DON levels and some decrease DON concentration.  Zearalenone is usually considered to be considered to be a problem with corn, but is also a problem in small grains such as wheat and barley.  Also discussed sampling techniques in truckloads of grain to minimize variability of mycotoxin analysis.

MINNESOTA

Weiping Xie reported on analytical method for DON to reduce chromatography retention time and increase the number of samples analyzed daily.  Barley strain that is resistant to the production of DON by F. graminearum.

MISSISSIPPI

H.K. Abbas reported that known ceramide synthase inhibitors are fumonisin B1 (FB1),

AAL toxin produced by Alternaria altemata and australifugin produced by Sporomiella australis.  Bioassay for phytotoxicity of these mycotoxins is based on the accumulation of sphigolipid precursors in duckweed (Lemna pausicostata) after exposure.  Fusarium sheath rot disease in rice caused by F. proliferatum resulted in the natural occurrence of fumonisins in rice.  After shelling, most of the fumonisin is found in the rice hull material; after milling the brown rice, most of the fumonisin is found in the bran and there are non-detectable levels in the white rice.  Ustilaginoides virens infects susceptible strains of rice and produces ustiltoxin.

BUSINESS MEETING

Business Meeting of SRIEG-51 called to order by Dr. G. Windham at 5:00 PM, January 25, 1999.

·        There was discussion about a Web site for SRIEG-51 and electronic submission of regional objectives.

·        Nominations for Secretary-Treasurer were made.  Rick Mascagni was elected to the position for the 1999-2000       term.

·        Gary Windham agreed to serve another year as Chair of SRIEG-51.

·        Bruce Manning will serve as Vice-Chair.

·        The site of the SRIEG-51 meeting in 2000 will be Starkville, Mississippi.

·        There was brief discussion about a merger with NC-129 in the future; no action was recommended or taken.

MISSOURI

G.E. Rottinghaus reported that analysis of corn silage for DON overestimated the concentration of DON when evaluated by a commercial ELISA kit method; TLC or HPLC results were 0.1-1.0 ppm when the ELISA results were 6-7 ppm.

D.R. Ledoux reported on the effect of moniliformin and fumonisin B1 on the immune systems of poultry (broilers and turkey poults):  both reduced antibody response and decreased resistance to bacterial infection.  Also, that immune system sensitivity to these two mycotoxins occurs at much lower levels than is required to decrease performance criteria.

NEBRASKA

Marty Dickman explained the DNA molecular mechanism for FB1 toxicity on a cell line; FB1 activates apoptosis in these cell lines.

NORTH CAROLINA

Gary Payne reported that an extract of corn seed has an inhibitory effect on the production of aflatoxins.  A chitinase compound has been isolated which causes reduced aflatoxin production.

WISCONSIN

F.S. Chu reported on research to generate monoclonal antibodies against the Fusarium mycotoxins FB1, DON, and related mycotoxins to improve existing ELISA tests.  Reported on the successful generation of polyclonal antibodies against FB4.  Also provided information on a means to regenerate immunoaffinity columns used for the purification of mycotoxins.  Reported on the different regulatory mechanisms for aflatoxigenic and non-flatoxigenic Aspergillus species.

 
State reports were completed and the meeting continued with a Discussion Session on Aflatoxin in Southern corn – the 1998 outbreak.

DISCUSSION SESSION

Dr. Neil Widstrom, USDA-ARS-IBPML, Tifton, Georgia, spoke briefly about two mycotoxin researchers, Dr. Gene Scott and Dr. Marcus Zuber, who recently died, and their contributions to mycotoxin research.  Commented about pre-harvest aflatoxin problem in the southeast, which was associated with insect damage.

Dr. William Wagner, USDA/CSREES Liaison, commented on Animal Health and Safety Programs of the USDA and new job openings in the USDA Extension Service.  Also provided information on USDA research funding opportunities.  Commented on establishment of multi-state research groups rather than the present concept of regional exchange groups.

Dr. Dave Wilson, Chair NC-129, commented on the proposal to broaden NC-129 to the multi-state group concept, which would add about five states from SRIEG-51.  These would include Alabama, North Carolina, Georgia, Louisiana, and Mississippi.  The combination of NC-129 and SRIEG-51 would create a multi-state project on mycotoxins in foods and feed grains.  The effect of combining the two groups needs to be evaluated.

Afternoon Session:

Dr. Richard Cartwright, University of Arkansas Cooperative Extension Service, reported on the aflatoxin problem of the 1998 Arkansas corn crop.  Nighttime temperatures much above normal, coupled with low rainfall and insect damage produced corn heavily contaminated with aflatoxin (aflatoxin B1 up to 400-500 ppb) in S.W. Arkansas.  Suggested ways to prevent contamination:  (1) plant early, (2) apply irrigation, (3) plant hybrid varieties, and (4) control insects.

Dr. Neil Widstrom, USDA-ARS, discussed strategies for controlling AF contamination in Southeastern corn.  Maize defenses include: (1) resistance to disease, (2) resistance to insects, (3) resistance to fungal infection, (4) resistance to AF contamination.  Ear-kernel damage by insects is highly correlated to AF contamination (r=0.78).  Tighter husks limit insect invasion, thereby, reducing AF contamination.  Management is the key to reducing AF contamination:  (1) adapted corn hybrids, (2) control insects, (3) fertilize properly, (4) tighter husks, (5) irrigate to prevent stress, (6) reduce plant stressors.

Dr. Steven Moore, LSU, commented that there is variability in AF testing, in the range of 8-163%.  Larger samples are better; about 15-20 pounds from a truckload of corn.  Grind the total sample with a Romer mill (Glen Mills), blend well, and take smaller sample from this preparation for laboratory analysis.

Dr. Gary Windham, USDA-ARS-CSRL.  Samples of corn were analyzed for AF; 315 samples (65%)> 20 ppb AF.  Approximately 25% of the 1998 corn crop was rejected for exceeding 20 ppb aflatoxin level.  Bt hybrids cannot stop AF contamination; AF contamination can occur without insect damage.

Dr. Thomas Isakeit, Texas A&M University, presented information on the AF problem in Texas.  Panhandle area incidence of AF contamination in:  (1) corn- 60%, (2) cottonseed- 100%, (3) sorghum- 85%.  Cause of the 1998 AF problem- stress due to drought conditions; there were increased levels of aflatoxins in non-irrigated corn growing areas.  He showed diagrammatically that the AF distribution among kernals on a single ear of corn varies greatly, some kernels may contain 0 ppb, but others nearby may contain as much as 10,000 ppb.

DISCUSSION SUMMARY

Meeting of SRIEG 51 and NC-129 was adjourned at 5:00 PM, January 26, 1999

   OFFICERS 1999