AraBAD Based Toolkit for Gene Expression and Metabolic Robustness Improvement in Synechococcus elongatus

As a novel chemical production platform, controllable and inducible modules in Synechococcus elongatus plus the ability of working in diurnal conditions are necessary. To the endeavors, inducible promoters, such as P(Trc), have been refined from Escherichia coli, but the inducer isopropyl-β-D-thiogalactoside may cause several side-effects. Meanwhile, to promote the efficiency, photomixotrophic cultivation has been applied in S. elongatus with the additional organic carbon sources. In this study, we developed L-arabinose based modules consisted of both the P(BAD) inducible promoter and the metabolism of L-arabinose in S. elongatus, since L-arabinose is an ideal heterologous feedstock for its availability and economic and environmental benefits. As expected, we achieved homogeneous and linear expression of the exogenous reporter through the P(BAD) promoter, and the biomass increased in diurnal light condition via introducing L-arabinose metabolism pathway. Moreover, the combined AraBAD based toolkit containing both the P(BAD) inducible module and the L-arabinose metabolism module could obtain gene expression and metabolic robustness improvement in S. elongatus. With the only additive L-arabinose, the novel strategy may generate a win-win scenario for both regulation and metabolism for autotrophic bio-production platforms.