Transcriptome analysis of non-ochratoxigenic Aspergillus carbonarius strains and interactions between some black aspergilli species

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 upregulated 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 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.

Carbon Catabolite Repression Gene AoCreA Regulates Morphological Development and Ochratoxin A Biosynthesis Responding to Carbon Sources in Aspergillus ochraceus

“…For the genes otaE and otaR2 located close to the OTA-putative gene cluster, the expression pattern under different carbon sources was different. This result could be an evidence for the unnecessary role of the two genes in OTA biosynthesis, confirming the results obtained for A. carbonarius, another main OTA-producing fungus and other OTA-producing fungi [11,12].…”

“…In 1993, OTA was listed as a possible carcinogenic substance (group 2B) by the International Agency for Research on Cancer [7]. Based on a comprehensive understanding of the dangers of OTA, researchers have paid more attention to the biosynthetic and regulatory mechanism of the toxin in the producer species [8][9][10][11][12][13].…”

Ochratoxin A Defective Aspergillus carbonarius Mutants as Potential Biocontrol Agents

“…Other general regulatory genes, such as veA and laeA, impact mycotoxin production [16,21]. Previous research has demonstrated that co-inoculation of an OTA-producing A. carbonarius strain with a non-OTA-producing A. carbonarius strain, which harbors a Y728H mutation in the otaA gene, can lower OTA levels [29]. If, as suggested by the authors, failed OTA production in this strain is due to a single point mutation, then there is a chance that this mutation can be reversed and lead back to an OTA-producer strain.…”

Isolation and Characterization of Paenibacillus polymyxa B7 and Inhibition of Aspergillus tubingensis A1 by Its Antifungal Substances

“…RNA-seq analysis showed 280 upregulated genes and 333 downregulated genes. Functional and GO enrichment analyses showed the downregulation of processes related to metabolic and oxidative processes as well as functions related to oxidoreductase and hydrolase activities [52].…”