Comparative Transcriptomic Analysis of Aspergillus niger Cultured on Peanut or Cashew Nut Flour Based Media

Native and recombinant fungal enzymes from Aspergillus species have been used for agricultural and food processing applications for many decades. Natural methods for attenuation of food allergens would benefit the food processing industry and may have application as digestive aids or prophylactic measures for those suffering from food allergy. To identify potential enzymes capable of aiding the metabolism of peanut and tree nut allergens, Aspergillus niger was grown in 4 different nut flour containing media and RNA sequencing and transcriptome analysis was used to identify differentially expressed genes. Transcript profiles from A. niger grown on media primarily composed of peanut or cashew nut flours were compared to growth on media containing glucose as the sole carbon source. When compared to the GMS control media, 2,961 genes were upregulated in the three media containing nut flour. Among these were many genes involved in protein metabolism including the oryzin protease and the aspartic endopeptidase aspergillopepsin. Similarly, several genes involved in the metabolism of carbohydrates including fructose, mannose, galactose, and starch were also upregulated. We identify several highly upregulated genes encoding proteins involved in peanut and cashew nut metabolism. The genes highlighted in this investigation may be useful as future food/food allergen processing enzymes, enable the development of dietary aids to assist in digestion and nutrient uptake, or potentially serve as new targets for fungal control on peanuts, tree nuts, or other agricultural products.