Novel Fusarium species from South African milk farm pastures

Facial eczema (FE) is a descriptive term for hepatogenous photosensitivity in sheep and cattle, caused by the mycotoxin sporidesmin. This toxin is produced by a saprophytic fungus, Pseudopithomyces chartarum. Facial eczema was first reported in 1894 in New Zealand and occurs frequently there, but was also reported in Argentina, Australia, the Netherlands, Portugal, South Africa, Turkey, the United States, and Uruguay. In South Africa, FE is increasingly recognized as a problem in the South African dairy industry and we thus wanted to explore fungal diversity in pastures. 

After a recent outbreak, mixed-grass samples were collected from Eastern Cape (EC) pasture in South Africa. Samples were surface disinfested and plated onto Potato Dextrose Agar (PDA) supplemented with antibiotics. After incubation at 24 C, fungal isolations were made, cultures preserved, then identified using both morphology and DNA sequencing of multiple gene regions.

Fungal communities were diverse with 738 strains isolated. These represented 57 genera. Three Pseudopithomyces species were identified with a taxonomic revision of the genus currently underway. Several other mycotoxigenic genera such as Fusarium and Aspergillus were also common. 

Knowledge regarding the role of fungal communities in causing FE and the general health of cattle in South Africa is lacking. Our study does however create a baseline knowledge for future investigations into their potential impacts on dairy pastures. Our findings provide new information on species distribution within the FIESC and the potential of mycotoxin production in pastures in the EC, while new species were introduced.