Fig. 5.
Logic gate for switching between glucose- and glycerol-utilizing states in K. pneumoniae. At the initial stage, cells grow using glucose instead of glycerol as carbon source, meanwhile, phosphoenolpyruvate carboxylase (PEPC) is expressed to benefit anaerobic respiration and cell proliferation. When glucose is exhausted, lactose is used to induce glycerol-utilizing state. Three antisense mRNA modules (A-Para, A-GPI, and A-GPY) are employed to turn off glucose metabolism, and Plac promoter drives the expression of dhaB and puuC for production of 3-HP. Bacteria prefer to metabolize glucose when it coexists with glycerol, therefore, when glycerol-utilizing state is turn on, the glucose-utilizing state must be turn off