Rapid quantification of Escherichia coli in food and media by bacteriophage T7 amplification and liquid chromatography-multiple reaction monitoring tandem mass spectrometry
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Rapid quantification of Escherichia coli in food and media by bacteriophage T7 amplification and liquid chromatography-multiple reaction monitoring tandem mass spectrometry
Rapid quantification of Escherichia coli in food and media by bacteriophage T7 amplification and liquid chromatography-multiple reaction monitoring tandem mass spectrometry
Banu M, Ng D, Zheng L, Goh LT, Bi X, Ow DS. Rapid quantification of Escherichia coli in food and media using bacteriophage T7 amplification and liquid chromatography-multiple reaction monitoring tandem mass spectrometry. J Biotechnol. 2014;192 Pt A:50‐58. doi:10.1016/j.jbiotec.2014.10.017
Abstract:
Conventional microbiological assays have been a valuable tool for specific enumeration of indicative bacteria of relevance to food and public health, but these culture-based methods are time-consuming and require tedious biochemical and morphological identification. In this work, we exploit the ability of bacteriophage T7 to specifically infect Escherichia coli and amplify nearly a 100-fold in 1–2 h. Bacteriophage amplification is integrated with liquid chromatography-multiple reaction monitoring tandem mass spectrometry (LC-MRM–MS/MS) for quantitation of phage-specific peptides. Heavy isotopic 15N labeled T7 is introduced as the inoculum phage and internal standard. Quantification is performed by determining the ratio of phage-specific peptides over the internal standard which value is proportional to E. coli numbers. A broad dynamic range of 6-log orders ranging from 3.0 × 10(3) to 3.0 × 10(9) CFU/ml is attained in LB, while between 4.1 × 10(4)–2.7 × 10(9) CFU/ml and 1.9 × 10(3)–3.0 × 10(7) CFU/ml was enumerated respectively in coconut water and apple juice. With this method, viable E. coli are quantified in 4 h with a detection limit of 3.0 × 10(3) CFU/ml, 4.1 × 10(4) CFU/ml and 1.9 × 10(3) CFU/ml in LB, coconut water and apple juice, respectively. This method has potential as a rapid tool for detection of fecal contamination during food bioprocessing and distribution to safeguard public health.
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Funding Info:
This research is supported by Bioprocessing Technology Institute, A*STAR