Estimation of bacterial contamination in ultrapure water: application of the anti-DNA antibody.

We constructed and established a hybridoma cell line that produces immunoglobulin G-type anti-DNA antibody. By using this antibody, we could successfully detect a single bacterial cell in ultrapure water (UPW). The detection system is composed of a membrane-supported western blotting-type immunoassay and a two-dimensional photon analyzer with high resolution. It can detect and count every bacterial cell in a wide field of view on a trapping filter i.e., a circle with an 18-mm diameter. This means 10 fg (10(-14) g) of bacterial DNA can be detected in the field. This system could be a useful tool for evaluating the number of bacteria contained by UPW and water used for medical purposes.