Comparative transcriptomic analysis of Aspergillus niger cultured in peanut or cashew nut flour based media

Abstract

Enzymes from the Aspergillus species have been used in food processing applications for decades. To identify peptidases and other enzymes capable of aiding the metabolism of peanut and tree nut allergens, Aspergillus niger was grown in three different nut-flour containing media and RNA sequencing and transcriptome analysis were used to identify differentially expressed genes. Transcript profiles from A. niger grown on media containing peanut or cashew nut flours were compared to growth on media containing glucose as the sole carbon source. Several highly upregulated genes encoding proteins likely involved in peanut and cashew nut metabolism were identified. When compared to the glucose media control, 2,423 genes were upregulated in media containing nut flour. Among these, there were many uncharacterized genes encoding putative peptidases such as gene_8419, gene_6678, gene_724, and gene_920 as well as previously characterized peptidases, such as oryzin and the aspartic endopeptidase aspergillopepsin. Similarly, several genes involved in the metabolism of carbohydrates including fructose, mannose, galactose, and starch were also upregulated. The peptidases and other enzymes encoded by the genes highlighted here may be useful as future food/food allergen processing enzymes to attenuate nut allergens, and may enable the development of dietary aids to assist in digestion and nutrient uptake.