Quantitative Proteomic Profiling of Fungal Growth, Development, and Ochratoxin A Production in Aspergillus ochraceus on High- and Low-NaCl Cultures

Abstract

Dry-cured meat products are worldwide food with high-salt content, and filamentous fungi are beneficial to the maturation process. However, some salt-tolerant strains of Aspergillus and Penicillium produce ochratoxin A (OTA) on these products and thus threaten food safety. In our study, proteomic analysis was performed to reveal the mechanism of adaptability to high-salt environment by Aspergillus ochraceus. Twenty g/L and 70 g/L NaCl substrates were used to provide medium- and high-NaCl content environments, respectively. The NaCl addition could induce fungal growth, but only 20 g/L NaCl addition could induce spore production while 70 g/L repressed it. Proteomics analysis identified 2646 proteins in A. ochraceus fc-1, of which 237 and 251 were differentially expressed with 20 g/L and 70 g/L NaCl addition, respectively. Potential factors affecting fungal growth and development were identified by GO and KEGG analyses of biological process, cellular component, and molecular function terms. The results revealed that ergosterol synthesis pathway was significantly upregulated with 20 g/L and 70 g/L NaCl addition. However, fungal growth and development including OTA production were complex processes associated with many factors including nutrient uptake, cell membrane integrity, cell cycle, energy metabolism, intracellular redox homeostasis, protein synthesis and processing, autophagy, and secondary metabolism. Reactive oxygen species may be an important window to understand the mechanism that medium-salt content was conducive to intracellular signal transduction while high-salt content caused oxidative stress. The findings would help to improve the processes and storage conditions of dry-cured meat products.

Unravelling the effect of control agents on Gnomoniopsis smithogilvyi on a chestnut‐based medium by proteomics

“…The main limitation of this study is that the proteins involved in their synthesis cannot be discussed due to the lack of knowledge about diplodiatoxin and the 3‐nitropropionic acid biosynthesis pathway and the absence of a database with G. smithogilvyi proteome. In this sense, most studies based on the relationship between proteins and mycotoxin biosynthesis are limited due to the technical restrictions of the equipment to detect proteins that are produced in lower quantities, such as mycotoxin‐related proteins, compared to proteins produced in higher quantities, such as energy‐related or structural proteins 54–56 . This inconvenience combined with the absence of information about the proteome of G. smithogilvyi and the biosynthetic pathway of these two new mycotoxins hindered the approach to study the mycotoxin biosynthetic pathway(s).…”