The effect of Hg2+ on the bioluminescence of Photobacterium leiognathi.

Photobacteria were used as test objects for rapid monitoring of ecotoxicants. Specific inhibitory effects of Hg(2+) on bioluminescence and cell growth as well as the lux gene expression of Photobacterium leiognathi were studied. The 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction assay was used to evaluate cellular proliferation and mortality. The luminescent inhibition effect on P. leiognathi cells was found to increase as cellular mortality increased; y = 0.744x - 4.8916, R² = 0.9794. However, this trend was not observed in cell growth processes. Quantitation of lux mRNAs by semi-quantitative RT-qPCR indicated that increases and decreases in luciferase mRNA integral level coincided with changes in luminescence intensity (R(2) = 0.93). Addition of Hg(2+) changed luminescence but without concomitant changes in extractable luciferase activity. Nevertheless, the presence of Hg(2+) changed lux gene expression. This phenomenon requires further research.