Construction of bioluminescent Lactobacillus casei CJNU 0588 for murine whole body imaging

Recombinant DNA pLuc2 which contains a firefly luciferase cDNA from the commercial pGL3-Basic plasmid vector was constructed for bioluminescent Escherichia coli and lactobacilli. The bioluminescent signal strengths of E. coli DH5α and L. casei CJNU 0588 transformed with pLuc2 were 2.78×109 and 1.19×106 p/s, respectively. Approximately 1010 cells of bioluminescent L. casei CJNU 0588 (pLuc2) were given orally to 6-week-old female Balb/c mice. The bioluminescent signal was detected from all three mice at 1 h and one mouse at 3 h but was not detected thereafter. The signal was also confirmed from an opened abdomen and the extracted GI tract of a mouse at 1 h. From the results, we have known that L. casei CJNU 0588 pass through the murine stomach and reach the colon and cecum 1 h after oral administration.