Aspergillus Niger An76 Siderophore Research

Most cells have an absolute requirement for iron. Due to the insolubility of ferric hydroxide, the element is often growth limiting under aerobic conditions. Microbial iron bioavailability is largely controlled by the presence of chelating agents that are able to solubilize environmental iron hydroxides and maintain the soluble iron concentration in an optimal domain for cell growth. These chelating agents, called siderophores, highly efficient and virtually Fe³⁺ specific chelators, are synthesized by bacteria and other microbes to overcome the low iron availability resulting from the minimal solubility of iron hydroxides. Siderophores selectively acquire and mediate iron transport and deposition inside the cell.Siderophores exhibit considerable structural variability and affinity for iron, which determines the growth of a microorganism under competitive conditions when availability is a limiting factor. Most siderophores may be classified as either hydroxamates or cathecolates. Fungi produce only hydroxamate type compound while bacteria produce hydroxamate as well as catecholate.Aspergillus niger An76 is a high pruduction of siderophore strain which was screened from 27 strains filaceous fungis.We had isolated and purificated the siderophore of An76 by gel separation, thin layer chromatography (TLC) and high-pressure liquid chromatography(HPLC). And we had mensurated some characters of the siderophore via amino acid analysis, MALDI-TOL MS and biotests. We find the siderophore is neither hydroxamate type or catecholate type, and isn't a polypeptide too.Two mutants of Aspergillus niger An76 , deficient in siderophore expression, have been isolated by UV mutagenesis.