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Transcriptome analysis of Ochratoxin A (OTA) producing Aspergillus westerdijkiae fc-1 under varying osmotic pressure

Summary

This research studied how salt concentration affects the production of ochratoxin A, a toxic substance produced by the fungus Aspergillus westerdijkiae that contaminates foods like coffee and grapes. Using advanced genetic analysis, scientists found that moderate salt levels (20 g/L) increase the fungus’s ability to produce this toxin by affecting specific genes. The findings help explain why OTA contamination is more common in salty foods like cured meats and suggest new ways to prevent this contamination and protect food safety.

Background

Ochratoxin A (OTA) is a toxic secondary metabolite produced by Aspergillus species that contaminates various food products and poses significant health risks. The International Agency for Research on Cancer has classified OTA as a Group 2B potential human carcinogen causing immunotoxicity, neurotoxicity, and genotoxicity. Understanding the molecular mechanisms of OTA production under different environmental conditions is essential for developing prevention and control strategies.

Objective

This study analyzed the transcriptome of Aspergillus westerdijkiae fc-1 strain under different NaCl concentrations (0, 20, and 100 g/L) using RNA-Seq technology to examine gene transcriptional changes linked to osmotic stress and OTA production. The research aimed to establish correlations between HOG1 expression and OTA biosynthesis genes to develop strategies for preventing OTA contamination in food.

Results

At 20 g/L NaCl, HOG1 was down-regulated by 78.06% while OTA biosynthesis genes otaA, otaB, and otaC were up-regulated by 3.26, 1.99, and 2.06 fold respectively. At 100 g/L NaCl, HOG1 was up-regulated by 28.32% and all OTA biosynthesis genes showed up-regulation (otaA: 27.06%, otaB: 36.80%, otaC: 19.59%, otaD: 5.72 fold). Significant changes were observed in metabolic pathways related to carbohydrate metabolism, cellular communication, ion transport, and ribosomal function.

Conclusion

This study revealed key correlations between HOG1 expression and OTA biosynthesis genes under different osmotic conditions. The findings suggest that moderate NaCl concentrations (20 g/L) stimulate OTA production through coordinated down-regulation of HOG1 and up-regulation of OTA biosynthesis genes. These insights provide a theoretical foundation for developing molecular strategies to control OTA contamination in food products.
  • Published in:Mycology,
  • Study Type:Experimental Study,
  • Source: PMID: 40415916, DOI: 10.1080/21501203.2024.2408259
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