We added a signal peptide (kp-sp, BBa_K2981006) from Actinobacillus at the N-terminal end of GFP (BBa_E0040) to construct a new part (BBa_K4183005) that allows GFP to be secreted extracellularly by E. coli.
We incubated E. coli containing BBa_K4183005 overnight, and centrifuged 2 ml of the bacterial solution. We subsequently observed the supernatant under UV irradiation. The results showed (Figure 1) that the supernatant of the experimental group emitted green fluorescence compared with the control group without kp-sp (BBa_K2981006), demonstrating that GFP containing kp-sp was secreted outside the cell.
Figure 1. Secretion of GFP without (left)/with (right) addition of signal peptide (kp-sp).