Improved bioluminescence-based endotoxin measurement method using a salt-resistant luciferase mutant

Endotoxin is a component of the cell wall of gram-negative bacteria and causes fever and shock symptoms upon entering the bloodstream. We previously demonstrated that the bioluminescence-based Limulus amebocyte lysate test is highly sensitive and rapid for measuring endotoxin. However, as the firefly luciferase reaction is inhibited in the presence of sodium chloride, the endotoxin detection method did not meet the validation guidelines under medical dialysis conditions (range of 75–125% of the measured values tested in water). Here, we used a salt-resistant luciferase mutant, which met the criteria for validation of endotoxin measurement. [Display omitted] •Endotoxin (ET) is routinely measured in medical dialysis.•Current methods for measuring ET are time-consuming or insensitive.•The bioluminescence-based ET measurement is rapid and highly sensitive.•The measured values of ET in dialysis must be 75–125% of those tested in water.•Our improved method using salt-resistant luciferase achieved the required criteria.