Isolation Of High Siderophore-producing Bacteria And The Utilization Of Insoluble Iron Compounds

Iron exists in the form of insoluble oxide or hydroxide in the environment,so high-efficiency mechanisms are crucial for organism to acquire iron.Among these mechanisms,siderophore-mediated-iron-acquire is a ubiquity pathway.Researches show that siderophore had wide application in industrial,agricultural and medical industry.15 high siderophore-producing strains were isolated by CAS method,and the siderophore units of these strains above 60%in the optimal medium.The stype of siderophore,produced by MB8,is catechol and the production was increased to 74.07%at 36 h in arginine medium;Z158 produced the hydroxamate siderophore in SM medium,and the siderophore unit was to 70.46%at 24 h.The siderophore stype of Z94 was mixed,containing hydroxamate and hydroxycarboxylate functional groups,and the production was 63.54%at 24 h,in MSA medium.Their bacteriostasis in vitro showed that MB8,Z94 and Z158 had wide antimicrobial spectrum;Comparative sequence analysis of 16S rRNA gene identified Z94 and Z158 as Pseudomonas aeruginosa,MB8 as Bacillus subtilis.Further analysis indicated that the inhibiting effect of Z158 and MB 8 were caused by siderophore secreted by themselves.Medium components and fermentation parameters affecting the siderophore production by B.subtilis MB8,were investigated at individual level,and the siderophore production of MB8 increased to 92.58%.After separation and purification,the molecular mass of siderophore was identified as 882 by UPLC-ESI-MS/MS,and the siderophroe contained 2,3-dihydroxy-benzoic acid,glycine and threonine.Further analysis found the siderophore secreted by MB8 accelerated the solubility and dissolution rate of goethite.The dissolution rate of high siderophore unit was 6 times as much as low siderophore units.Siderophore produced by Z158 dissolved the insoluble poor crystal iron hydroxide,and maked the biomass of Z158 increased by 46.09%.Besides,MB8 had a good survial rate under gastrointestinal simulate fluid,was sensitive to antibiotics and didn't produce hemolysin.Also,Siderophore had scavenging effect on DPPH radical.Results of this study could be the theory foundation for practical application of strains.