• KSBB Journal
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• v.17 no.6
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• pp.571-576
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• 2002

Recombinant E. coli DH5 ${\alpha}$/pSB311 was made by cloning the genes encoding bacterial luciferase and aldehyde substrate proteins from Photohabdus luminescense, to complement defects of Lumistox, which is normally used in bioassays to monitor toxic substances in water environmental systems. The conditions for stable light production by the recombinant strains were investigated with respect to cell growth stage, cell number, and buffer conditions. The optimum growth stage was a middle-exponential stage with an OD$_{660nm}$ value of 0.6-0.7. ADout 10$^{6}$-10$^{7}$ cells per test tube was optimum for stable light emission. The effect of buffer was not significant if an optimum viable cell number was maintained. The bioluminescence of the recombinant E. coli harboring the lux operon of Photohabdus luminescense was not affected by temperature, while the bioluminescence of Lumistox was temperature sensitive. The recombinant E. coli was more sensitive to heavy metals (Cd, Cu, Hg, Zn) than Lumistox, because it does not require high concentrations of NaCl in the buffer.