Research On Siderophore-producing Strain Agrobacterium Sp. ZX09

Iron, as a necessary element in microbial life, is involved in most metabolic processes, such as respiration and DNA synthesis. In despite of its high content in the lithosphere, ranked fourth, iron’s various existence forms, like crystalline states, amorphous states, ferric oxides or ferric hydroxide complexes, make a low utilization for microorganism. In order to survive, microorganism, under a low-iron-content environment, secretes a secondary metabolite,named siderophore. Siderophore is a small molecular weight compound(500～1500Da) which can chelate Fe3+with high efficiency from host cells or surroundings and translate the iron into cells to meet the need of growth.Various physiological and biochemical experiments and whole genome sequencing have been done to the strain Agrobacterium sp. ZX09. Bioinformation analysis showed that, two enzymes,2,3-dihydro-2,3-dihydroxybenzoate dehydrogenase and synthase, not produced by ribosomes, are involved in the synthesis and secretion of siderophore. After locating the position of the two genes, we speculated the other related genes and predicted the whole synthesis passway and structure of siderophore. In order to confirm the ability to synthesis and secrete siderophore by ZX09, chrome azurol S (CAS) assay were carried out. Furthermore, a suicide plasmid pEMG, bearing gene segment TatA homologous to part of the key gene3773, was used to construct a deficient mutant.The mutant strain failed to produce a chrome-azurol-S-reactice material in liquid or solid medium.