Team:Hong Kong HKU/Characterization
Characterisation of lac promoter in Salmonella
As part of the bronze medal requirement and a our part construction, we characterised a promoter part,
BBa_R0010
In this characterisation, we used this part which contains a lac promoter to express fluorescent markers in two different species, Escherichia coli and Salmonella Typhimurium (E. coli and S. typhimurium) to test whether this is a constitutive promoter in S. Typhimurium.
E. coli and S. Typhi belong to the same order, Enterobacteriaceae. Lactose fermentation ability is used to differentiate them. S. Typhimurium does not have the ability to ferment lactose like E. coli does. In this characterisation experiment, this lac promoter is transformed to S. Typhimurium and E. coli as a control to see the difference in the expression level of the downstream red fluorescent markers.
As the data suggests, this promoter is a constitutive promoter in S. Typhimurium as there is no difference in signals with or without IPTG. Moreover, the expression level using this promoter in the absence of IPTG in S. Typhimurium is much higher than that in E. coli and this thus encouraged us to use lac promoter in our part construction to drive the expression of protein of interest.