Colony Counting System for Easy Plate

LuciPac A3 Filter Assay a method that is able to detect microorganisms in liquids has been presented. Below is the abstract of the presentation during IAFP 2023.
Poster (PDF) is also available for download.

Chiaki Hara, Yuko Ichiyanagi, and Shigeya Suzuki
Kikkoman Biochemifa Company



Water microorganisms are a useful indicator for the quality of drinking water, and for the maintenance of water treatment facilities and circulating cooling water systems. Since culturing methods take several days, a rapid assay is required for quick response measures for incidents.


A rapid test for microorganism-derived total adenylates (ATP+ADP+AMP, A3) was developed using a combination of the A3 test and filtration of water sample and eliminating the need for culture. The correlation between microorganism-derived A3 and viable bacterial counts was evaluated in this project.


Eight kinds of samples were collected from tap water, well-water, utility waste water, and cooling tower water. These samples were stored at 25 °C for 0-18 days to assess the change of microbial quality. Each sample (10 mL, total 29 samples) was filtered through a syringe filter to eliminate extracellular A3 and trap microorganisms. Successively, microorganism-derived A3 was extracted by the surfactant. The extract was measured by the A3 test (LuciPacTM A3 Surface/LumitesterTM Smart, Kikkoman Biochemifa Company), and the measurement output was relative light units (RLU). Colony counts were measured as colony forming units (CFU) and determined using R2A agar medium after 48 hours of incubation at 30 °C.


During the sample storages, RLU values and log CFU increased as time passed. In 4 samples, bacteria and RLU values decreased at the end. The measurement values for all samples were 1.2-4.1 log RLU and 2.2-6.3 log CFU/mL. A positive correlation was found between RLU and CFU/mL in logarithmic scale (y = 0.622x - 0.147, r2 = 0.831).


It was demonstrated that the microbial quality of water can be assessed using a quick (ca. 3 min) test and simple procedures - the combination of filtration treatment and A3 test. These results indicated that this assay is useful for rapid hygiene control of water and water-related facilities.

Download poster (PDF) from here.


The Combination of Filtration and ATP+ADP+AMP Assay for the Assessment of Microbial Quality of Water (