Hokkaido University Research Profiles


Simple Pathogen Measuring Devices

Pathogens can be measured by simply adding samples to the kit.

We have developed technology that allows measurement of the concentration of E. coli, coliforms, and enterococci within as early as 1 hour and as late as 12 hours after simply adding 0.1 mL of a sample (sewage, wastewater, food extract, drinking water) to the measurement kit and installing it in the device.

Content of research

Currently, the measurement of pathogenic bacteria requires a much time and labor, including the preparation of agar media, multiple dilutions of a large amount of sample, and 24-hour incubation. We have developed a kit that can measure pathogenic bacteria (fecal contamination indicator bacteria) such as E. coli, coliforms, and enterococci simply by injecting 0.1 mL of liquid sample or food extract. Compared to the current general bacteria measurement technology, this is an extremely simple technology that requires only mixing of the sample with the solution. The bacterial concentration is measured using a fluorescent dye. The fluorescent dye can be used even if the liquid is turbid, so the concentrations of various bacteria, even in turbid samples such as wastewater or food extracts, can be measured directly without any pretreatment.

  • Fig. 1 Photograph of a sample containing E. coli under a black light after it was placed in a kit (microplate) and incubated. Blue fluorescence can only be seen in the holes and wells to which samples containing E. coli were added. Wells that do not fluoresce indicate that E. coli was not present in the sample added to these wells.

  • Fig. 2 The vertical axis shows the incubation time required for the fluorescence intensity to exceed a certain threshold (called the positive time) after the kit is installed in the device and the fluorescence intensity is measured at 10-minute intervals, and the horizontal axis shows the E. coli concentration as measured with a commercial kit. A linear relationship was observed between the E. coli concentration and the positive time obtained with this technology. This indicates that the present technology can replace the commercial kits (the cost of measuring one sample is about 1,000 yen).

Potential for social implementation

  • ・Bacterial analysis in water
  • ・Bacterial analysis in food
  • ・Bacterial analysis in hospitals (MRSA, etc.)
  • ・Bacterial analysis in cowsheds (Staphylococcus aureus, etc.)
  • ・In this way, it can be used for simple analysis of bacteria in any place.

Appealing points to industry and local governments

So far, we have only targeted E. coli, coliforms, and enterococci, but we are also interested in other bacteria (Staphylococcus aureus, drug-resistant bacteria, etc.). We are also working on a simple method to measure the concentrations of metals, viruses, and chemical substances besides bacteria. We are also looking forward to receiving requests for analysis of new targets (research topics) from people in other fields other than our specialty of environmental engineering.