Separation and colorimetric detection of Escherichia coli by phage tail fiber protein combined with nano-magnetic beads.

Bin Hong, Yanmei Li, Wenhai Wang, Yi Ma, Jufang Wang

Mikrochimica acta 2023 May 05

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A colorimetric detection method for Escherichia coli (E. coli) in water was established based on a T7 phage tail fiber protein-magnetic separation. Firstly, the tail fiber protein (TFP) was expressed and purified to specifically recognize E. coli, which was verified by using fusion protein GFP-tagged TFP (GFP-TFP) and fluorescence microscopy. Then TFP conjugated with magnetic beads were applied to capture and separate E. coli. The TFP was covalently immobilized on the surface of magnetic beads and captured E. coli as verified by scanning electron microscopy (SEM). Finally, polymyxin B was used to lyse E. coli in solution and the released intracellular β-galactosidase (β-gal) could hydrolyze the colorimetric substrate chlorophenol red-β-D-galactopyranoside (CPRG), causing color change from yellow to purple. The high capture efficiencies of E. coli ranged from 88.70% to 95.65% and E. coli could be detected at a concentration of 102 CFU/mL by naked eyes. The specificity of the chromogenic substrate was evaluated using five different pathogen strains as competitors and tests with four kinds of real water samples showed recoveries of 86.00% to 92.25%. The colorimetric changes determined by visual inspection can be developed as an efficient platform for point-of-care detection of E. coli in resource-limited regions. © 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.

Citation

Bin Hong, Yanmei Li, Wenhai Wang, Yi Ma, Jufang Wang. Separation and colorimetric detection of Escherichia coli by phage tail fiber protein combined with nano-magnetic beads. Mikrochimica acta. 2023 May 05;190(6):202