https://ag.arizona.edu/research/cottylab/apdfs/Cotty%20and%20Jaime%20Climate.pdf

Influences of climate on aflatoxin producing fungi and aflatoxin contamination.

Taxonomy of Aspergillus section Flavi and their production of aflatoxins, ochratoxins and other mycotoxins

Two novel species from Aspergillus section Flavi from different species of Arachis (peanuts) in Argentina are described as Aspergillus arachidicola sp. nov. and Aspergillus minisclerotigenes sp. nov. Their novel taxonomic status was determined using a polyphasic taxonomic approach with phenotypic (morphology and extrolite profiles) and molecular (β-tubulin and calmodulin gene sequences) characters. A. minisclerotigenes resembles Aspergillus flavus and Aspergillus parvisclerotigenus in producing aflatoxins B1 and B2, cyclopiazonic acid, kojic acid and aspergillic acid, but in addition it produces aflatoxins G1 and G2, aflavarins, aflatrem, aflavinines, parasiticolides and paspaline. This species also includes several isolates previously assigned to A. flavus group II and three Australian soil isolates. A. arachidicola produces aflatoxins B1, B2, G1 and G2, kojic acid, chrysogine and parasiticolide, and some strains produce aspergillic acid. The type strain of A. arachidicola is CBS 117610T =IBT 25020T and that of A. minisclerotigenes is CBS 117635T =IBT 27196T. The Mycobank accession numbers for Aspergillus minisclerotigenes sp. nov. and Aspergillus arachidicola sp. nov. are respectively MB 505188 and MB 505189 (http://www.mycobank.org).

Two novel aflatoxin-producing Aspergillus species from Argentinean peanuts.

Human activities affect both the size and structure of fungal populations. Construction, war, recreation, and agriculture disrupt large expanses of vegetation and soil; disruption causes redistribution of fungal propagules and makes nutrients available to fungi. Many fungi, including the aspergilli, exploit these human engineered resources. This results in the association of large fungal populations with various human activities, especially agriculture. When crops are grown or animals raised, fungi are also grown. From a human perspective, most fungi associated with cultivation increase inadvertently. Human activity, however, partly dictates which and how many fungi occur and the fungi, both directly and through fungal products, influence human activities, domestic animals, and even humans themselves.

Agriculture, Aflatoxins and Aspergillus

Soil isolates of Aspergillus flavus from a transect extending from eastern New Mexico through Georgia to eastern Virginia were examined for production of aflatoxin B1 and cyclopiazonic acid in a liquid medium. Peanut fields from major peanut-growing regions (western Texas; central Texas; Georgia and Alabama; and Virginia and North Carolina) were sampled, and fields with other crops were sampled in regions where peanuts are not commonly grown. The A. flavus isolates were identified as members of either the L strain (n = 774), which produces sclerotia that are >400 μm in diameter, or the S strain (n = 309), which produces numerous small sclerotia that are 10 μg of aflatoxin B1 per ml. The percentages of isolates producing >10 μg of aflatoxin B1 per ml ranged from 0 to 52% in the remaining regions of the transect; other isolates were often nonaflatoxigenic. A total of 53 of the 126 L-strain isolates that did not produce aflatoxin B1 or cyclopiazonic acid were placed in 17 vegetative compatibility groups. Several of these groups contained isolates from widely separated regions of the transect.

Regional differences in production of aflatoxin B1 and cyclopiazonic acid by soil isolates of aspergillus flavus along a transect within the United States.

Peanuts, cottonseed, rice, and sorghum from Texas were sampled over a 3-year period. To insure adequate isolation of alfatoxin-producing species of fungi, low-quality lots were sampled at a rate greater than their respective proportional representation. Aflatoxins were found each year in peanut and cottonseed and were found in 2 of 3 years in rice and sorghum. Aflatoxins were detected in all four crops. The Aspergillus flavus group was much more prevalent in peanut and rice than in cottonseed and sorghum. Of the isolates of the A. flavus group, 96% from peanuts, 79% from cottonseed, 49% from sorghum, and 35% from rice produced aflatoxins. The average toxin production of isolates from rice was much less than that from peanuts, cottonseed, or sorghum. More than 90% of all isolates of the A. flavus group were identified as the species A. flavus. A. parasiticus was isolated from all four crops. Only A. parasiticus produced aflatoxin G.

Aflatoxin production of species and strains of the Aspergillus flavus group isolated from field crops.

Total aflatoxin concentrations produced by Aspergillus parasiticus, isolate 64-R8, in Czapek9s broth fortified with corn steep liquor increased proportionately as the concentration of corn steep was increased from 0.5 to 8.0% (v/v) until maximal growth, as measured by dry mycelial weight, was reached. Thereafter, aflatoxin concentrations declined more rapidly than the rate of autolysis of mycelial material. Data are presented which indicate that the concentration of corn steep liquor also affects the ratio of production of aflatoxin B1 and B2 to that of aflatoxin G1 and G2. Further, this ratio also varies with time of incubation. Although both growth of the fungus and aflatoxin production are stimulated by the addition of corn steep to the basic medium, the stimulation of toxin production is much greater than fungus growth.

Harry W. Schroeder

Papers

Aflatoxin production of species and strains of the Aspergillus flavus group isolated from field crops.

Effect of Corn Steep Liquor on Mycelial Growth and Aflatoxin Production in Aspergillus parasiticus

Factors influencing the development of aflatoxins in some field crops

Aflatoxins: Some factors affecting production and location of toxins in Aspergillus flavus-oryzae

Milling quality of Belle Patna rice in experimental storage: A study of the effects of field fungi on subsequent invasions by storage fungi