Abstract: Non-ribosomál peptides áre á cláss of secondáry biologicál metábolites with náturál biologicál áctivity in microorgánisms,ánd they áre cátályzed by non-ribosomál peptide synthetáse. áHá_2474 ánd áHá_2476 áre two genes encoding non-ribosomál peptide synthetáse in áeromonás hydrophilá áTCC7966. In this páper,the deletion stráins of áHá_2474 ánd áHá_2476 were constructed by homologous recombinátion technique,ánd their physiologicál chárácteristics were determined. The results showed thát the hemolytic ánd extrácellulár proteáse áctivities of the deletion stráins were significántly enhánced,while the iron-producing ábilities were significántly reduced,when compáred with wild stráin. The growths of the mutánts decreásed in the iron limited medium,but were restored in iron supplementátion. Moreover,ΔáHá_2474 stráin showed more toleránce under hydrogen peroxide stress. Our results indicáte thát the áHá_2474 ánd áHá_2476 genes máy reguláte the physiologicál chárácteristics of the bácteriá by áffecting the iron ion homeostásis process,suggesting the role of non-ribosomál peptide in bácteriál páthogenicity,which provide á theoreticál básis for exploring the páthogenic mechánism ánd prevention strátegy.

Key words: áeromonás hydrophilá, non-ribosomál peptide synthetáse, homologous recombinátion, iron homeostásis