Comparison of aflatoxin production of Aspergillus flavus at different temperatures and media: proteome analysis based on TMT

Authors: WANG, PENG - Ocean University Of China; Chang, Perng Kuang; KONG, QING - Ocean University Of China; SHAN, SHIHUA - Shandong Peanut Research Institute; Wei, Qijian - Mei Mei

Submitted to: International Journal of Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/23/2019
Publication Date: 8/24/2019
Citation: Wang, P., Chang, P.-K., Kong, Q., Shan, S., Wei, Q. 2019. Comparison of aflatoxin production of Aspergillus flavus at different temperatures and media: proteome analysis based on TMT. International Journal of Food Microbiology. 310:108313. https://doi.org/10.1016/j.ijfoodmicro.2019.108313.
DOI: https://doi.org/10.1016/j.ijfoodmicro.2019.108313

Interpretive Summary: Aflatoxins are potent carcinogenic compounds. Elimination of aflatoxins in food and feed is important because of associated health risks. Aflatoxin formation is affected by biotic and abiotic factors. A proteomic study of A. flavus growing in different types of media and at different temperatures was carried out to better understand the underlying mechanisms responsible for aflatoxin biosynthesis. The results show that proteins with a diversity of functions including those belonging to specific metabolic pathways are differentially expressed under the study conditions. The work furthers our knowledge of physiological factors in regulating the production of aflatoxin, and it will help to devise strategies for reducing fungal toxin contamination of crops.

Technical Abstract: Aflatoxin production of Aspegillus flavus is affected by abiotic factors such as temperature, water activity, and oxidative stress. These factors likely affect different metabolic pathways and result in altered aflatoxin production. In the present study, aflatoxin production in different culture medium types (liquid or solid) and at different temperatures (28' or 37') was determined. Proteomes of A. flavus under the study conditions also were obtained. The result showed that A. flavus produced more aflatoxin at 28' than at 37'. It also produced more aflatoxin on solid agar medium than in liquid broth. Proteomic analysis showed that a total of 5,029 proteins were identified from A. flavus NRRL3357, of which 1,547 were differentially expressed in the medium set and 546 were differentially expressed in the temperature set. GO and KEGG analyses were further carried out to identify associated biological processes, molecular functions, and cellular components as well as related metabolic pathways. Specifically, compared to the liquid medium, extracellular hydrolases for nutrient uptake and proteins involved in sclerotial development were differentially expressed on solid medium (p<0.05). Enzymes associated with oxidative stress were down-regulated in liquid medium but up-regulated at 28' (p<0.05). The work shows that aflatoxin synthesis is affected by a variety of factors including nutrient uptake, oxidative stress, sclerotial development, and G protein-signaling and valine, leucine and isoleucine degradation pathways. A model summarizing the regulation of aflatoxin biosynthesis in A. flavus is presented.