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

Authors: Mattison, Chris; Mack, Brian; Cary, Jeffrey

Submitted to: Journal of Applied Biology & Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/3/2021
Publication Date: 9/1/2021
Citation: Mattison, C.P., Mack, B.M., Cary, J.W. 2021. Comparative transcriptomic analysis of Aspergillus niger cultured in peanut or cashew nut flour based media. Journal of Applied Biology & Biotechnology. 9(05):56-63. https://doi.org/10.7324/JABB.2021.9508.
DOI: https://doi.org/10.7324/JABB.2021.9508

Interpretive Summary: Food allergies represent a significant medical burden. Food allergies are caused by certain proteins in some foods that act as allergens. Natural undiscovered enzymes that may be able to degrade, destroy, or modify peanut and tree nut allergens would benefit public health and the food processing industry. Enzymes from the fungus Aspergillus niger have been used for agricultural and food processing applications for many decades. To identify new enzymes capable of aiding the metabolism of peanut and tree nut allergens the fungi Aspergillus niger was grown in media containing nut flour and the genes that were needed for metabolism of the nut proteins were sequenced and characterized. There were 2,961 genes encoding proteins involved in peanut and tree nut metabolism that were ‘turned on’ during growth in nut flour media. Among these genes were many uncharacterized genes encoding protein degrading enzymes. More in-depth characterization of these protein degrading enzymes will be needed to determine how well they act to destroy or modify nut allergens. Many other genes involved in the breakdown of carbohydrates and starch were also identified and characterized. The proteins encoded by the genes highlighted in this investigation may be useful as future food allergen processing enzymes to degrade nut allergens or enable the development of new dietary aids to assist in digestion and nutrient uptake.

Technical Abstract: 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. Several highly upregulated genes encoding proteins involved in peanut and cashew nut metabolism were identified. When compared to the glucose control media, 2,961 genes were upregulated in the three media containing nut flour. Among these were many uncharacterized genes peptidases, 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 proteins encoded by the genes highlighted in this investigation may be useful as future food/food allergen processing enzymes to attenuate nut allergens, enable the development of dietary aids to assist in digestion and nutrient uptake, or potentially serve as new targets for control of fungal contamination of peanuts, tree nuts, or other agricultural products.