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United States Department of Agriculture

Agricultural Research Service

Research Project: CONTROL OF TOXIC ENDOPHYTIC FUNGI WITH BACTERIAL ENDOPHYTES AND REGULATION OF BACTERIAL METABOLITES FOR NOVEL USES IN FOOD SAFETY

Location: Toxicology and Mycotoxin Research

Title: Analyses of black Aspergillus species of peanut and maize for ochratoxins and fumonisins

Authors
item Palencia, Edwin -
item MITCHELL, TREVOR
item Snook, Maurice
item GLENN, ANTHONY
item GOLD, SCOTT
item HINTON, DOROTHY
item Scherm, Harald -
item RILEY, RONALD
item BACON, CHARLES

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 16, 2013
Publication Date: May 1, 2014
Repository URL: http://handle.nal.usda.gov/10113/58737
Citation: Palencia, E.R., Mitchell, T.R., Snook, M.E., Glenn, A.E., Gold, S.E., Hinton, D.M., Riley, R.T., Bacon, C.W. 2014. Analyses of black Aspergillus species of peanut and maize for ochratoxins and fumonisins. Journal of Food Protection. 77(5):805-813. DOI: 10.4315/0362-028X.JFP-13-321.

Interpretive Summary: A group of fungi referred to as the black aspergilli are widely spread in the agricultural environment. Included in this group are species such as Aspergillus niger. This group contaminates several valued crops such as corn and peanuts. Recently it was discovered that this group on grapes can produce two mycotoxins, the ochratoxins and the fumonisins. Both toxins are carcinogenic to humans, livestock, and poultry. The fumonisins are also toxic to corn and peanut causing seedling blight; therefore, the health concern is for both plant and animal. Our early studies documented that these black species live within corn and peanuts as endophytes. The question now of concern is can they produce these two mycotoxins? Further, the identities of the species responsible for infecting corn and peanuts are all similar when viewed under the microscope. We developed a molecular method that identified these species, and we conducted a survey of corn and peanuts from several southeastern and Midwestern states. We also developed a technique of assaying the ability of species to produce the two mycotoxins. The results of testing 150 isolates from the sampling sites indicated that of the five species identified, the major species was A. niger, and that no species was found that could produce the ochratoxin, but the majority produced the fumonisins. The impact of these findings on human health is high, especially since corn and peanuts and their products are major food items. The results of this study add another group of fungi that can produce the fumonisins on corn and brings some concern to their occurrence on peanuts. The production of the highly toxic fumonisin isomer, fumonisin B1, by isolates of the black aspergilli of peanuts and corn was not known prior to this study and their occurrence as endophytes on both crops should be a major concern for food and feed safety.

Technical Abstract: The genus Aspergillus section Nigri, or the black aspergilli, represents genetically closely related species that produce the mycotoxins ochratoxins, and the fumonisins. Fumonisin B1 is of particular concern, since it also is a virulence factor for maize. Our preliminary data indicated that black aspergilli can develop asymptomatic endophytic infection with maize and peanuts. An endophytic infection by species of this group is a potential problem, since under favorable conditions these infections can lead to the accumulation of ochratoxins and the fumonisins in crops. In the present report, the isolation and identification of species of black aspergilli as endophytes from maize and peanuts were determined, as well as their abilities to produce the ochratoxins and the fumonisins on autoclaved maize. A total of 150 strains from peanuts and maize were isolated from several southeastern and Midwestern states. It was determined that A. nigri (A. nigri var. nigri) was the dominant species (87%) while A. foetidus, A. japonicus, A. tubingensis, and A. carbonarius were infrequently isolated. Based on HPLC and LCMS analyses, 54 strains of A. nigri var. nigri produced fumonisins B1 (12%), B2 (23%), and B3 (18%). This is a first report of B1 production by isolates of the black aspergilli from an American cereal crop and a food and feed legume. None of the isolates produced detectable amounts of ochratoxins.

Last Modified: 8/19/2014
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