Fig. 5
Validation of feasibility of riboswitch SY-btuB in different performances. a Mechanism of VB12 dependent riboswitch SY-btuB double plasmid work mode. VB12 directly binds to the riboswitch region, producing a conformational change in the secondary structure of mRNA, and thus inhibiting lacI gene expression and causing the gfp reporter to show a fluorescent signal. For cells containing a very low concentration of VB12, the ribosome binding site (RBS) is unstructured. This allows for efficient translation of lacI gene and then lacI and can bind lacO and repress gfp expression. b The microscopic image of S. meliloti 320 and fluorescence microscopic images of Sm320, Sm320-L6 and Sm320-N8 cells carrying SY-btuB sensor plasmid, respectively. c FACS (Fluorescence Activated Cell Sorting) results of three strains mixed with equal optical density. Strains exhibiting top 1% of the fluorescence values were selected by FCM. The screened strains were then distinguished the selected colonies by Summit 5.2 analysis