Genetic manipulations
The genome of E3 was used as the template to amplify genetic fragments. The coding sequence of icd , sucA and sucB were amplified with primers icdF/icdR, sucAF/sucAR and sucBF/sucBR, respectively. The fragments were inserted into pIB139 betweenNde I and Xba I sites using gibson assembly, yielding plasmid pIB-icd, pIB-sucA and pIB-sucB, respectively. Primers sucAF3 and sucAR3 were used for the amplification of leader and coding sequence ofsucA . The resulting fragment was next cloned into pIB-sucB atEcoR I via gibson assembly, yielding the plasmid pIB-sucBA.