Protein biomarker for early diagnosis of microbial toxin contamination: Using Aspergillus flavus as an example

Abstract

Abstract Microbial toxins are important factors that contribute to human diseases and food losses. Predicting the production of these toxins before they occur is a significant challenge. In this study, we innovatively developed a strategy called targeted acquisition of toxin‐related immunogen (TATRI) to identify early diagnostic biomarkers for microbial toxins. Taking Aspergillus flavus as an example, we employed an immunoassay‐based screening approach to identify nanobodies that exhibited significant response signals to different toxigenic strains. Subsequently, we isolated and purified the specific immunogen pre‐aflatoxin biomarker PAB‐01 that bound to the selected nanobody. The results showed that the level of PAB‐01 was positively correlated with the toxin‐producing ability of A. flavus strains and could be detected before the production of aflatoxins. It met the essential requirements as an early diagnostic biomarker for aflatoxin contamination. Protein identification and bioinformatics analysis revealed that PAB‐01 is a glycoprotein that can be secreted into the extracellular space. It is located on chromosome 5 of A. flavus and belongs to the 75 family of glycoside hydrolases. Furthermore, we used 7 g/kg as the critical concentration of PAB‐01 to diagnose the risk of aflatoxin contamination in stored peanuts, with an accuracy rate of 75.9% for high‐risk samples. In summary, this work provides a promising approach for the identification of protein biomarkers prior to microbial toxin production and the establishment of early diagnostic techniques for microbial toxins.

Keywords

• Aspergillus flavus
• biomarker
• early diagnosis
• microbial toxins
• protein purification