Development of a colorimetric and fluorescence dual-mode immunoassay for the precise identification of Alicyclobacillus acidoterrestris in apple juice

Alicyclobacillus acidoterrestris is the main hazardous factor leading to deterioration of commercialized fruit juices, as it can result in serious economic loss to the industry. Currently detection methods require high-end equipment with low specificity and sensitivity. To address these problems, we describe herein a monoclonal antibody with high specificity to A. acidoterrestris using a cell wall protein as antigen. A colorimetric and fluorescence dual-mode immunoassay system employing the prepared antibody was then developed based on the quenching effect of oxidized p-phenylenediamine on fluorescein. This approach could accurately differentiate between the target of interest and other bacteria species with enhanced limit of detection of 4.8 x 10(2) CFU/mL. Apple juice artificially contaminated with A. acidoterrestris at the concentration of 1 CFU/mL could be determined as positive after 24 h enrichment. The resulting immunoassay platform provided a rapid, convenient, sensitive, and selective way for detecting A. acidoterrestris, holding great potential as a robust tool for preventing spoilage in the fruit juice industry.