Colorimetric Detection of a Bacterial Biomarker Using a Modified Litmus Test

Published: February 29, 2024

Abstract

Source: Tram, K., et al. Colorimetric Detection of Bacteria Using Litmus Test. J. Vis. Exp. (2016).

This video demonstrates a colorimetric E. coli detection method, involving an E. coli biomarker activating a DNAzyme, leading to cleavage of RNA linkage and detachment of a DNAzyme-urease conjugate. A subsequent colorimetric assay detects the E. coli biomarker through ammonia-induced pH changes.

Protocol

1. Preparing E. coli Cells for Testing For a desired cell suspension, transfer 1 ml of cultured stock to a 1.5 ml microfuge tube. Centrifuge the cells at 6,000 x g for 10 min at 4 °C. Carefully remove the supernatant without disturbing the cell pellet. Add 10 µl of reaction buffer to the cell pellet and resuspend the cells. Sonicate the cell suspension for 5 min. Transfer the cell suspension to an ice box for 5 min. Sonicate the cell s…

Divulgaciones

The authors have nothing to disclose.

Materials

Ethylenediaminetetraacetic acid (EDTA) VWR AMRESCO 105
Sodium Hydroxide (NaOH) pellets BIO BASIC CANADA INC SB6789
Tris-base VWR AMRESCO 497
Urea VWR AMRESCO M123
Xylenecyanol FF SIGMA-ALDRICH X-4126
0.04% Phenol red SIGMA-ALDRICH P3532
10x T4 polynucleotide kinase reaction buffer Lucigen 30061-1
E. coli K12 (MG1655) ATCC ATCC700926
Magnetic Bead (BioMag) Bangs Laboratories Inc
Magnetic Seperation Rack New England BioLabs S1506S
Microfuge tubes Sarstedt 72.69
Cell culture incubator Eppendorf Scientific M13520000
Branson Ultrasonic cleaner Branson N/A

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Colorimetric Detection of a Bacterial Biomarker Using a Modified Litmus Test. J. Vis. Exp. (Pending Publication), e22001, doi: (2024).

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