Novel detection of Escherichia coli β-d-glucuronidase activity using a microbially-modified glassy carbon electrode and its potential for faecal pollution monitoring

The electrochemical detection of Escherichia coli β-d-glucuronidase activity as a means of monitoring water pollution by faecal material was investigated using separate Moraxella- and Pseudomonas putida-modified glassy carbon electrodes. The former was more sensitive and selective. The Moraxella-modified biosensor was 100 times more rapid and sensitive than the spectrophotometric detection of β-d-glucuronidase activity. The experimental limit of detection of the biosensor was two c.f.u. per 100 ml polluted water sample within 20 min. The biosensor gave a linear response to commercial β-d-glucuronidase concentration between 0.2 ng and 2 μg ml-¹. The biosensor detected activity of β-d-glucuronidase from viable but non-culturable (VBNC) cells and can therefore serve as a presence or absence device for rapid water quality monitoring.