Screening for Bongkrekic Acid in Food Using a Monoclonal Antibody-Based Indirect Competitive Enzyme-Linked Immunosorbent Assay (icELISA)

Pseudomonas cocovenenans subsp. farinofermentans is a pathogenic bacterium that causes the poisoning of fermented rice products. Its isomeric products, bongkrekic acid (BA) and isobongkrekic acid (IBA), have become popular research topics. In this study, we developed a heterologous-coating strategy for high-sensitivity indirect competitive enzyme-linked immunoassay (icELISA) for BA and IBA using monoclonal antibodies (mAbs). The optimized procedure exhibited an IC50 of 5.49 ng/mL, a limit of detection of 0.99 ng/mL, and a linear range from 2.12 to 14.21 ng/mL. Notably, this method exhibited negligible cross-reactivity to other small toxins, and the recoveries of the samples, including rice noodles, Auricularia auricula, and flat rice noodles, ranged from 92.0%–111.9%, 105.6%–115.0%, and 83.2%–109.0%, respectively, with coefficients of variation below 12%. A comparison of the recoveries of high-performance liquid chromatography-mass spectrometry (HPLC-MS) and icELISA demonstrated that the developed approach provides good accuracy and reliability. Overall, the simple preparation of IBA combined with the suitability of icELISA for high-throughput analysis is efficient and cost-effective, making it suitable for routine screening of food.