Related Experiment Video
Updated: Oct 17, 2025
In Situ Measurement and Correlation of Cell Density and Light Emission of Bioluminescent Bacteria
Published on: June 28, 2018
Improved bioluminescence-based endotoxin measurement method using a salt-resistant luciferase mutant
Satoshi Yawata1, Kenichi Noda2, Ai Shimomura2
1Medical Related Devices Department, DKK-TOA Corporation, Sayama Saitama, 350-1388, Japan; Unit of Molecular Biotechnology, Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Hiroshima, 739-8530, Japan.
A novel salt-resistant luciferase mutant enables accurate endotoxin detection in medical dialysis fluids. This advancement overcomes limitations of previous bioluminescence assays, ensuring reliable measurement of bacterial endotoxins.
Area of Science:
- Biochemistry
- Microbiology
- Medical Diagnostics
Background:
- Endotoxin, a gram-negative bacterial cell wall component, triggers severe systemic responses like fever and shock when entering the bloodstream.
- The Limulus amebocyte lysate (LAL) test, utilizing bioluminescence, offers a sensitive and rapid method for endotoxin quantification.
- A significant limitation of the firefly luciferase reaction in the LAL test is its inhibition by sodium chloride, hindering validation under physiological conditions.
Purpose of the Study:
- To develop a robust endotoxin detection method suitable for medical dialysis conditions.
- To overcome the sodium chloride inhibition issue in bioluminescence-based endotoxin assays.
Main Methods:
- Utilized a genetically engineered, salt-resistant firefly luciferase mutant.
- Applied the modified luciferase in a bioluminescence-based Limulus amebocyte lysate assay.
- Validated the assay's performance under conditions mimicking medical dialysis fluid composition.
Main Results:
- The salt-resistant luciferase mutant successfully maintained the bioluminescence reaction in the presence of physiological salt concentrations.
- Endotoxin measurements using the modified assay met the stringent validation criteria (75-125% of measured values in water).
- The assay demonstrated high sensitivity and rapidity for endotoxin detection in simulated dialysis fluid.
Conclusions:
- A salt-resistant luciferase mutant effectively resolves the inhibition issue in bioluminescence-based endotoxin detection.
- This optimized LAL assay is validated for reliable endotoxin measurement in medical dialysis applications.
- The findings pave the way for improved safety and quality control in hemodialysis and related medical procedures.
