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

Ochratoxin A (OTA) is a toxic secondary metabolite produced by the species which can contaminate various food products. This study analysed the transcriptome of the fc-1 strain under NaCl concentrations of 0, 20, and 100 g/L using RNA-Seq technology to examine gene transcriptional changes linked to osmotic stress and OTA production. Significant changes were observed in metabolic-pathways associated with carbohydrates, cellular communication, and hydrolase activity under 20 g/L NaCl. The gene, associated with osmotic pressure regulation was down-regulated by 78.06%. In contrast, OTA biosynthesis genes , , and were up-regulated by 3.26 fold, 1.99 fold, and 2.06 fold, respectively. Conversely, the gene was down-regulated by 43.50%. At 100 g/L NaCl, pathways related to ion transport, peptide metabolism, ribosomal function, and transmembrane transporter protein activities were significantly up-regulated. The gene was up-regulated by 28.32% and OTA biosynthesis genes , , , and showed up-regulation of 27.06%, 36.80%, 19.59%, and 5.72 fold, respectively. The study highlights the role of metabolic pathways in osmotic stress regulation and the correlations between expression and OTA biosynthesis genes, providing insights for developing strategies to prevent OTA contamination in food.