APART FROM THE SPORIDESMIN-PRODUCING FUNGUS, PASTURES IN THE EASTERN CAPE ARE ALSO INFECTED WITH FUSARIUM AND OTHER MYCOTOXIGENIC FUNGI

Fungi in dairy pastures in the Eastern Cape are known to adversely affect cattle health, but the diversity of fungal species has not been well-studied. However, the outbreak of Facial eczema (FE) (caused by the mycotoxin sporidesmin A produced by Pseudopithomyces toxicarius) in the area in 2020, provided an opportunity to study the presence of other species. To that effect, the authors cited collected mixed pasture samples from 14 pasture-based dairy farms in the Tsitsikamma area affected by FE. The aim was to investigate which fungal species are present and whether they may affect cattle health.

A total of 708 strains were isolated from 95 mixed pasture samples and identified based on DNA sequenced data. A total of 132 species representing 55 genera were present. Fusarium was the most isolated (207 strains; 21 species; 55 samples), followed by Penicillium (75 strains; 22 species; 27 samples), Pseudopithomyces (69 strains; 2 species; 21 samples), Cladosporium (54 strains; 6 species; 23 samples), Epicoccum (52 strains; 6 species; 24 samples) and Bipolaris (38 strains; 3 species; 19 samples). Several strains could not be identified which may represent new or previously uncharacterised species. The phylogenetic analyses of the Pseudopithomyces genera revealed the presence of Ps. palmicola and, as expected, Ps. toxicarius in the pastures samples.

In summary: The study showed more diverse communities than previous surveys conducted during outbreaks of FE or kikuyu poisoning identified. This could be attributed to earlier species identifications that relied on morphological characters, which often led to misidentifications, thus underestimating overall fungal diversity. The incorporation of DNA sequencing in modern taxonomy has resulted in an increased number of species described in several genera. In particular, genera such as Aspergillus, Fusarium and Penicillium have seen a sharp increase in the rate of species descriptions in the past decade. This highlights the importance of incorporating molecular techniques such as DNA sequencing to accurately assess fungal diversity in general, but particularly also in complex genera like Fusarium.

In addition to the high presence (>40%) of Fusarium spp and strains, the presence of several other mycotoxigenic species from the genera Aspergillus, Fusarium and Penicillium was confirmed. The high presence of Fusarium as a potent mycotoxigenic genus is of particular concern.