Checkpoint enrichment for sensitive detection of target bacteria from large volume of food matrices

Authors: REN, WEN - Purdue University; CABUSH, ABIGAIL - Purdue University; IRUDAYARAJ, JOSEPH - Purdue University

Submitted to: Analytica Chimica Acta
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/8/2020
Publication Date: 7/8/2020
Citation: Ren, W., Cabush, A., Irudayaraj, J. 2020. Checkpoint enrichment for sensitive detection of target bacteria from large volume of food matrices. Analytica Chimica Acta. 1127:114-121.
DOI: https://doi.org/10.1016/j.aca.2020.06.025

Interpretive Summary: One critical need in food safety testing is the ability to enrich and detect target bacterial pathogens in large sample volumes in a complex matrix. This study describes a practical strategy for rapid enrichment of the target bacteria from a large volume of food sample. The enrichment was conducted with blended lettuce samples circulated through antibody modified polyester (polyethylene terephthalate, PET) pads to specifically capture the cells. The obtained PET pads with the captured target pathogens were then used for enhanced, rapid pathogen detection. The enrichment method requires only a simple syringe-based setup with an antibody modified PET pad. This approach demonstrates a promising means to improve the detection of target bacteria with a high degree of sensitivity and specificity and due to its simplicity and cost could be used in low resource settings.

Technical Abstract: A gap in biosensor development is the ability to enrich and detect targets in large sample volumes in a complex matrix. To bridge this gap, our goal in this work is to propose a practical strategy, termed as checkpoint-style enrichment, for rapid enrichment of the target bacteria from large volume of food samples with particulates and evaluate its enrichment and improvement in detection. The checkpoint-style enrichment was conducted with antibody modified polyethylene terephthalate (PET) pads as capture substrates. In our approach, blended lettuce sample cocktail was circulated through antibody modified PET pads such as a checkpoint in the sample solution pathway, where target pathogens were selectively captured with immobilized antibodies. The obtained PET pads with the captured target pathogens were then used for enhanced detection by colorimetry. To render the checkpoint-style enrichment approach practical and applicable for on-site rapid screening tests, only a simple syringe-based setup with antibody modified PET pad was required. The developed method could process up to 50 ml of lettuce cocktail blended from 5g samples and purposefully inoculated with E. coli O157:H7. Overall, the enrichment method developed required only 40 min of sample processing time. After enrichment, as low as 100 CFU/ml of E. coli O157:H7 could be detected by a simple colorimetric procedure due to the enhancement from the proposed checkpoint-style enrichment in the presence of ~3000 CFU/ml of non-target bacteria. A linear response was obtained from blank to 100000 CFU/ml of E. coli O157:H7 in blended lettuce samples. The conceptualized approach demonstrates a promising means to improve the detection of target bacteria with a high degree of sensitivity and specificity and could be used in low resourse settings.