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

Summary

A fungus called Aspergillus westerdijkiae produces a toxic substance called Ochratoxin A (OTA) that commonly contaminates foods like coffee, grapes, and wheat. Researchers used advanced gene analysis techniques to understand how salt concentration affects the fungus’s ability to produce this toxin. They found that moderate salt levels actually increase OTA production, while very high salt levels activate defense mechanisms that reduce it. These findings could help develop better strategies to prevent this dangerous contamination in our food supply.

Background

Ochratoxin A (OTA) is a toxic secondary metabolite produced by Aspergillus species that contaminates various food products and poses significant health threats to humans and animals. Aspergillus westerdijkiae is recognized as one of the most significant OTA producers. Understanding how environmental factors like osmotic stress regulate OTA biosynthesis is essential for developing contamination control strategies.

Objective

This study aimed to analyze 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 sought to understand correlations between HOG1 expression and OTA biosynthesis genes to develop strategies for preventing OTA contamination.

Results

At 20 g/L NaCl, significant metabolic changes occurred in carbohydrate, cellular communication, and hydrolase activity pathways, with HOG1 down-regulated by 78.06% and OTA genes otaA, otaB, otaC up-regulated by 3.26, 1.99, and 2.06 fold respectively. At 100 g/L NaCl, ion transport and ribosomal pathways were up-regulated, HOG1 was up-regulated by 28.32%, and all OTA genes showed increased expression with otaD showing 6.49-fold increase. The study revealed an inverse correlation between HOG1 expression and OTA biosynthesis at moderate salt levels.

Conclusion

The research highlights the critical role of metabolic pathways in osmotic stress regulation and establishes correlations between HOG1 expression and OTA biosynthesis genes. The findings provide molecular insights for developing strategies to prevent OTA contamination in food products by understanding how osmotic pressure influences fungal OTA production mechanisms.
  • Published in:Mycology,
  • Study Type:Experimental Study,
  • Source: PMID: 40415916, DOI: 10.1080/21501203.2024.2408259
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