Abstract
Aspergillus carbonarius consistently produces large amounts of ochratoxin A (OTA), a mycotoxin with nephrotoxic effects on animals and humans. In the present study, we analyzed the transcriptional changes associated to OTA production in three atypical non-ochratoxigenic strains of A. carbonarius. In addition, in vitro interactions between ochratoxigenic strains of A. carbonarius and A. niger and non-ochratoxigenic strains of A. carbonarius and A. tubingensis were studied in order to evaluate their potential for controlling OTA production. RNA-seq analysis revealed that there are 696 differentially expressed genes identified in the three non-OTA-producing strains, including 280 up-regulated and 333 down-regulated genes. A functional and gene ontology enrichment analysis revealed that the processes related to metabolic and oxidation processes, associated with functions such as oxidoreductase and hydrolase activity were down regulated. All the genes related with OTA biosynthesis in A. carbonarius were the most down-regulated genes in non-ochratoxigenic strains. We also showed that these strains possess a deleterious mutation in the AcOTApks gene required for OTA biosynthesis. Moreover, one of these strains gave the best control of OTA production resulting in an OTA reduction of 98–100% in co-inoculation with an ochratoxigenic strain of A. niger and an OTA reduction of 79–89% with an ochratoxigenic strain of A. carbonarius. Results of this study provided novel insights into the knowledge of the OTA biosynthetic pathway in these non-ochratoxigenic wild strains, and showed the biocontrol potential of these strains.
Highlights
Ochratoxin A (OTA) is a nephrotoxic mycotoxin that has been related to human and animal diseases
81% of short reads were successfully mapped on the A. carbonarius genome
In A. carbonarius the transcription factor AcOTAbZIP which is located between AcOTAp450 and AcOTAhal is homologous to otaR1 found in A
Summary
Ochratoxin A (OTA) is a nephrotoxic mycotoxin that has been related to human and animal diseases It is classified as a 2B carcinogen by the International Agency for Research on Cancer (Pfohl-Leszkowicz and Manderville, 2012) and can be found in a variety of common foods and beverages (Pit and Hocking, 2009). This mycotoxin is produced by several species of Penicillium and Aspergillus, being Aspergillus carbonarius the main OTA source on grapes and derived products. The genes involved in the OTA biosynthetic pathway have not been completely characterized, even if many studies have been carried out in several OTA-producing fungi (Wang et al, 2016).
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