Fig 3.

Glucose dehydrogenase is necessary for glucose inhibition of prodigiosin (GIP). Complementation of the rig-10 mutant (Δcrp gdhS) glucose insensitivity phenotype using the wild-type S. marcescens gdhS gene or the E. coli gcd gene expressed from a medium-copy-number plasmid. The vector pMQ132 was used as a negative control. Cultures were incubated at 30°C for 20 h; “− glucose” indicates growth in LB (black bars); “+ glucose” indicates growth in LBG (gray bars). Prodigiosin levels (A₅₃₄), normalized by culture turbidity (OD₆₀₀ nm) (A), and culture pH (B) are shown. The charts show an average of three independent biological replicates per condition and genotype, and error bars indicate one standard deviation. The experiment was performed twice with consistent results. Strain CMS1687 with pMQ132 served as the crp mutant control.