Abstract：Lux operon codes a series of proteins that mediate the autofluorescence of luminous bacteria by catalyzing long-chain fatty acids molecules through the oxidation reduction reactions. Methods for constructing luminescent Escherichia coli transformed with lux operon were introduced to study distribution and survival of E. coli in vitro and in vivo. In this study, we transformed the pL1217 plasmid carrying with lux operon into E.coli DH5α strain, and performed the biological characteristics of E. coli growth curve assay and fluorescence spectrum analysis of lux operon. Meanwhile, the bioluminescent assay of E. coli transfected with lux operon were performed by infrared video data imaging system (IVIS) kinetics to test whether the luminous bacteria could inherited stably in vivo. The E. coli cells with lux operon at the log phase were collected and injected into the cecum of ICR mouse (Mus musculus). 24 h after infection, fluorescent bacteria from mouse small intestine occurred and the number of the bacteria was counted. The results showed that the E. coli transfected with lux operon in log phase produced strong blue/green fluorescence that last more than 16 h in vivo, and indicated that E. coli cells were capable of colonizing in small intestine and maintaining fluorescence without disturbing its normal activities. The study of E. coli cells colonizing in mouse bowel provides an experimental model that can be used to monitor the pathogenic E. coli activities in animal bowel in vivo and investigate the pathogenesis enteral infections by bacteria.
