Quartz crystal assay for rapid determination of nitrifying bacterial cells

Abstract

A quartz crystal analysis (QCA) system was developed for the rapid and simple detection of nitrifying bacteria. This method is based on the fact that nitrifying bacterial cells that reacted with anti-nitrifying bacteria antibodies were able to be analysed by QCA. Latex beads immobilized with the antibody were used for the selective detection of the nitrifying bacterial cells. A suspension of the latex beads was added to the tube chamber of the quartz crystal and incubated for 5 min at 37°C. When the suspension of nitrifying bacterial cells was injected in the chamber, the resonant frequency decreased with increasing cell concentration within 1 min. For the reference bacterial cells, the resonant frequency did not change. A good correlation was observed between the change in frequency (−ΔF) and the bacterial concentration. One measurement could be completed in 10 min.

Keywords:

• Environment
• Bacterial detection
• QCA
• Immunoassay
• Water

Acknowledgements

We wish to thank Dr H. Ohmura and Mrs T. Nagai of Yakult Central Institution for Microbiological Research for their helpful discussion. This research was supported in part by Kurita Water and Environment Foundation.