Campus Units

Chemistry, Food Science and Human Nutrition

Document Type

Article

Publication Version

Accepted Manuscript

Publication Date

11-30-2018

Journal or Book Title

Analytical Chemistry

DOI

10.1021/acs.analchem.8b04751

Abstract

We have previously investigated the extraction and concentration of bacteria from model systems using magnetic ionic liquid (MIL) solvents, while retaining their viability. Here, we combine MIL-based sample preparation with isothermal amplification and detection of Salmonella-specific DNA using Recombinase Polymerase Amplification (RPA). After initial developmental work with Serratia marcescens in water, Salmonella Typhimurium ATCC 14028 was inoculated in water, 2% milk, almond milk or liquid egg samples and extracted using one of two MILs, including: trihexyl(tetradecyl)phosphonium cobalt(II) hexafluoroacetylacetonate ([P66614+][Co(hfacac)3–]) and trihexyl(tetradecyl)phosphonium nickel(II) hexafluoroacetylacetonate ([P66614+][Ni(hfacac)3–]). Viable cells were recovered from the MIL extraction phase after the addition of modified LB broth, followed by a 20 min isothermal RPA assay. Amplification was carried out using supersaturated sodium acetate heat packs and results compared to those using a conventional laboratory thermocycler set to a single temperature. Results were visualized using either gel electrophoresis or nucleic acid lateral flow immunoassay (NALFIA). The combined MIL-RPA approach enabled detection of Salmonella at levels as low as 103 CFU mL-1. MIL-based sample preparation required less than 5 min to capture and concentrate sufficient cells for detection using RPA, which (including NALFIA or gel-based analysis) required approximately 30 - 45 min. Our results suggest the utility of MILs for the rapid extraction and concentration of pathogenic microorganisms in food samples, providing a means for physical enrichment that is compatible with downstream analysis using RPA.

Comments

This accepted article is published as Hice, S.A.,Clark, K.D., Anderson,J.L., Brehm-Stecher,B.F., Capture, Concentration and Detection of Salmonella in Foods Using Magnetic Ionic Liquids and Recombinase Polymerase Amplification. Analytical Chemistry, 2018. DOI: 10.1021/acs.analchem.8b04751. Posted with permission.

Copyright Owner

American Chemical Society

Language

en

File Format

application/pdf

Available for download on Saturday, November 30, 2019

Published Version

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