Assembly of T4 bacteriophages with β-galactosidase for electrochemical detection of Escherichia coli K12

This research developed an electrochemical biosensor based on T4 bacteriophages assembled with beta-galactosidase (β-gal) for Escherichia coli K12 ( E. coli K12) detection. The β-gal Soc fusion proteins were affinity-assembled on the Hoc − Soc − T4 phage capsid, exhibiting superior substrate affinity and enhanced stability compared to the free enzyme. The antibodies were immobilized on the multiwalled carbon nanotube/gold nanoparticle modified electrode, and then the engineered β-gal T4 was bonded the bacterial cells captured by the antibodies, constructing the electrochemical biosensor. The biosensor can detect E. coli K12 as low as 6 CFU/mL within 90 mins utilizing catalytic events of β-gal T4. The biosensor exhibited high specificity, distinguishing live target bacteria from non-target bacteria or dead target bacteria, which is attributed to its dual recognition mechanism involving antibody and β-gal T4. The biosensing platform can be extended to other bacteria by customizing phage-enzyme combinations, enabling bacterial detection in food, environment and other fields.