Fig. 4From: Establishing an innovative carbohydrate metabolic pathway for efficient production of 2-keto-l-gulonic acid in Ketogulonicigenium robustum initiated by intronic promotersDetection of intronic promoter activity. a–d The images of gfp gene expression in recombinant strains initiated by different promoters. Strains harboring plasmids of (a) pBBR1MCS-2, (b) pBBR-PtufB_gfp (c) pBBR-P1_gfp or (d) pBBR-P2_gfp were photographed with a fluorescence microscope. e The whole cell relative fluorescence intensity (RFU/OD) of different strains was measured using a fluorescence microplate reader. Data in e represents the mean ± SD of 3 replicatesBack to article page