Mycotoxins produced by Fusarium proliferatum and F. pseudonygamai on maize, sorghum and pearl millet grains in vitro

Hester F Vismer; Gordon S Shephard; Liana van der Westhuizen; Pamella Mngqawa; Vuyiswa Bushula-Njah; John F Leslie

doi:10.1016/j.ijfoodmicro.2019.02.016

Mycotoxins produced by Fusarium proliferatum and F. pseudonygamai on maize, sorghum and pearl millet grains in vitro

Int J Food Microbiol. 2019 May 2:296:31-36. doi: 10.1016/j.ijfoodmicro.2019.02.016. Epub 2019 Feb 20.

Authors

Hester F Vismer¹, Gordon S Shephard², Liana van der Westhuizen³, Pamella Mngqawa⁴, Vuyiswa Bushula-Njah⁵, John F Leslie⁶

Affiliations

¹ Mycotoxicology and Chemoprevention Research Group, Institute of Biomedical and Microbial Biotechnology, Cape Peninsula University of Technology, PO Box 1906, Bellville 7535, South Africa. Electronic address: hester.vismer33@gmail.com.
² Mycotoxicology and Chemoprevention Research Group, Institute of Biomedical and Microbial Biotechnology, Cape Peninsula University of Technology, PO Box 1906, Bellville 7535, South Africa. Electronic address: shephardg@cput.ac.za.
³ Oxidative Stress Research Centre, Institute of Biomedical and Microbial Biotechnology, Cape Peninsula University of Technology, PO Box 1906, Bellville 7535, South Africa. Electronic address: vanderwesthuizenl@cput.ac.za.
⁴ Mycotoxicology and Chemoprevention Research Group, Institute of Biomedical and Microbial Biotechnology, Cape Peninsula University of Technology, PO Box 1906, Bellville 7535, South Africa. Electronic address: mngqawap@cput.ac.za.
⁵ Forestry and Agricultural Biotechnology Institute, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa. Electronic address: vuyiswa.bushula@fabi.up.ac.za.
⁶ Kansas State University, 4024 Throckmorton Plant Sciences Center, 1712 Claflin Avenue, Manhattan, KS 66506-5502, USA. Electronic address: jfl@ksu.edu.

PMID: 30826540
DOI: 10.1016/j.ijfoodmicro.2019.02.016

Abstract

Maize (Zea mays), sorghum (Sorghum bicolor) and pearl millet (Pennisetum glaucum) are basic staple foods for many rural or poorer communities. These crops are susceptible to plant diseases caused by multiple species of Fusarium, some of which also produce mycotoxins, including fumonisins and moniliformin that are detrimental to both humans and domesticated animals. Eighteen potentially toxigenic Fusarium strains were isolated from maize (n = 10), sorghum (n = 7) and pearl millet (n = 1) growing in the same field in Nigeria. The 17 strains from maize and sorghum were all F. proliferatum and the one strain from pearl millet was F. pseudonygamai. Under conducive conditions, the 17 F. proliferatum strains produced fumonisins, 11 in relatively large quantities (700-17,000 mg total fumonisins, i.e., FB₁ + FB₂ + FB₃/kg culture material), and six at <45 mg/kg. Ten F. proliferatum strains produced >100 mg of moniliformin per kg culture material with a maximum of 8900 mg/kg culture material. All strains could use all grains for growth and toxin production, regardless of the host from which they were isolated. Isolates varied in the amount of toxin produced on each substrate, with toxin production a property of the strain and not the host from which the strain was recovered. However, the extent to which a toxin-producing phenotype could be altered by the grain on which the fungus was grown is consistent with subtle genetic × environment interactions that require a larger data set than the one presented here to rigorously identify. In conclusion, there is significant variation in the ability of strains of F. proliferatum to produce fumonisins and moniliformin on maize, sorghum and millet. If the amount of toxin produced on the various grains in this study reflects real-world settings, e.g., poor storage, then the consumers of these contaminated grains could be exposed to mycotoxin levels that greatly exceed the tolerable daily intakes.

Keywords: Fumonisin; Fusarium; Moniliformin; Subsistence farming.

MeSH terms

Animals
Cyclobutanes / analysis*
Edible Grain / microbiology
Fumonisins / analysis*
Fusarium / isolation & purification
Fusarium / pathogenicity*
Mycotoxins / analysis*
Nigeria
Pennisetum / microbiology*
Plant Diseases / microbiology
Sorghum / microbiology*
Zea mays / microbiology*

Substances

Cyclobutanes
Fumonisins
Mycotoxins
moniliformin