Influence of environmental factors on tenuazonic acid production by Epicoccum sorghinum: An integrative approach of field and laboratory conditions

Sorghum is the fifth most cultivated and consumed grain in the world. However, this grain is frequently contaminated with toxins from fungi. The present study evaluated the effects of environmental factors on tenuazonic acid (TeA) production by Epicoccum sorghinum in the field and in controlled labo...

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Bibliographic Details
Published in:The Science of the total environment 2018-11, Vol.640-641 (C), p.1132-1138
Main Authors: Oliveira, Rodrigo C., Nguyen, Hang N., Mallmann, Carlos A., Freitas, Rogerio S., Correa, Benedito, Rodrigues, Debora F.
Format: Article
Language:English
Subjects:
Alternaria
Ascomycota - physiology
Ecophysiology
Gene expression
LC-MS/MS
Mycotoxins
Phoma sorghina
Sorghum
Tenuazonic Acid - metabolism
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Summary:Sorghum is the fifth most cultivated and consumed grain in the world. However, this grain is frequently contaminated with toxins from fungi. The present study evaluated the effects of environmental factors on tenuazonic acid (TeA) production by Epicoccum sorghinum in the field and in controlled laboratory conditions. In this study, 50 sorghum grain samples were collected from summer and autumn growing seasons and analyzed for TeA contamination using LC-MS/MS. To further understand the ecophysiology of this fungus, an isolated strain of E. sorghinum from the field was investigated for its development and TeA production under controlled environmental conditions in the laboratory. In the ecophysiological investigation, the effects of water activity (0.90, 0.95, 0.99) and temperature (18, 22, 26 and 30 °C) were evaluated on the radial growth, enzymatic production and expression of TAS1, which is the gene involved in TeA production. Results showed that in the field, the summer season presented the highest TeA average level in the grains (587.8 μg/kg) compared to level found in the autumn (440.5 μg/kg). The ecophysiological investigation confirmed that E. sorghinum produces more actively TeA under environmental conditions simulating the summer season. Optimum growth, maximum TAS1 gene expression, and higher extracellular enzymatic production were observed at 26 °C with a water activity of 0.99. Pearson correlation analyses showed that the production of TeA highly correlates with fungal growth. The present study demonstrates that abiotic factors in a combined approach of field and laboratory conditions will assist in predicting the driving environmental factors that could affect growth of E. sorghinum and TeA production in sorghum grains. [Display omitted] •Combined field and laboratory approaches to predict mycotoxin contamination.•The mycotoxin TeA was detected in all sorghum grains analyzed in the field.•Hot and humid conditions play an important role in TeA contamination on sorghum.•E. sorghinum produces more TeA in conditions simulating the summer season.
ISSN:0048-9697
1879-1026
DOI:10.1016/j.scitotenv.2018.05.293