Label-free immunoassay for multiplex detections of foodborne bacteria in chicken carcass rinse with surface plasmon resonance imaging

Authors: Park, Bosoon; WANG, BIN - Orise Fellow; CHEN, JING - Orise Fellow

Submitted to: Foodborne Pathogens and Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/2/2020
Publication Date: 3/8/2021
Citation: Park, B., Wang, B., Chen, J. 2021. Label-free immunoassay for multiplex detections of foodborne bacteria in chicken carcass rinse with surface plasmon resonance imaging. Foodborne Pathogens and Disease. http://doi.org/10.1089/fpd.2020.2850.
DOI: https://doi.org/10.1089/fpd.2020.2850

Interpretive Summary: Bacteria contaminations of Salmonella and E. coli have caused breakouts of foodborne illness every year in the US. Traditionally, cell culture and polymerase chain reaction (PCR) have been used to detect these bacteria in food sample. The disadvantages of these methods include long operation time, heavy labor, and dependence on well-trained microbiology professionals to obtain reliable results. Surface plasmon resonance imaging (SPRi) offers a new method with significantly faster detection time and the capability of identifying multiple bacteria species at the same time without any additional labelling process. Here, SPRi is used for the simultaneous detection of Salmonella spp. and Shiga-toxin producing E. coli in commercial chicken rinse samples without any pretreatment of labeling to increase the detection signal. Experimental conditions such as antibody concentrations and buffer pH values were optimized. The lowest bacteria concertation this SPRi method can detect were evaluated. Further improvements will be made to detect even lower concentrations of bacteria with or without additional labeling. Then this SPRi detection method can be used in different areas of food industry to detect multiple bacteria pathogens at the same time.

Technical Abstract: The frequent outbreaks of foodborne pathogens have stimulated the demand of biosensors capable of high-throughput screening of contaminated food samples with least labeling process. Surface plasmon resonance imaging (SPRi) is an emerging optical technique for rapid screening of various biospecies coexisting in real-world samples. In this study, SPRi was used in simultaneous label-free detection of multiple foodborne pathogens, mainly Salmonella spp. and Shiga-toxin producing E. coli, in commercial chicken carcass rinse. The antibodies for their corresponding target bacteria were immobilized on the same sensor chip to conduct high-throughput detections, and monitored via real-time SPRi images. The antibody immobilization concentrations on sensor chip surface were optimized to be ranging from 0.25 mg/mL to 1.0 mg/mL, and the antibody capture activity is independent of immobilization buffer pH values. Anti-Salmonella showed best limit of detection in the level of 106 CFU/mL for the multiplex detection, and was improved to 1.0 CFU/mL with bacteria enrichment. Moreover, the SPRi signals revealed the complex interference effects among different bacteria species during the multiplex detections with heterogeneous bacteria solutions. Overall, SPRi sensor chips demonstrate the great potential in high-throughput screening of multiple pathogenic bacteria coexisting in chicken carcass rinse. Further improvements in sensitivity and sensor chip design could make this platform a highly versatile and high-throughput biosensor to detect pathogens in food matrices.