Bioluminescent monitoring of intracellular ATP during fermentation

The luciferase gene was introduced as a probe into a cell in order to develop a bioluminescent monitoring of intracellular ATP during fermentation. Two plasmids were constructed with two types of promoters. One was pLac-Luc, which had the luciferase gene under the lac promoter to be expressed at a high level. The other was pTet-Luc, which had the luciferase gene under the tetracycline promoter to be stably expressed. A threonine-overproducing strain of Escherichia coli (No. 29-4) was transformed with each plasmid. The recombinant E. coli strains were characterized in their growth, threonine production and luciferase expression. The bioluminescence produced intracellularly from expressed luciferase was detected during fermentation -in a non-destructive manner. The bioluminescent intensity reflected both intracellular ATP and luciferase levels, and the results indicate that stable expression of a luciferase reporter is essential for monitoring intracellular ATP.