Screening Of Fungi With Siderophore Activity And Preliminary Study On The Effect Of Siderophore Compounds On Microbial Community Structure

Siderophore is a kind of microbial secondary metabolites with metal ion chelating ability,which has wide application prospects in the fields of medicine,environmental remediation and healthy food.Because the research on siderophore from alkaline environment fungi is still limited,we carried on the related alkaline environment strains screen,active compounds separation and soil microbial ecological effects of active compounds investigation.In this study,6 candidate strains were obtained through the two stages screen procedures(preliminary and secondary screening).After the molecular biology identification,the strain FEDT-092 was determined as the Talaromyces fungus(with higher similarity with Talaromyces flavus);The strain FECH-031 was determined as the Aspergillus fungus(with higher similarity with Aspergillus jensenii);The strain FECH-074 was determined as the Penicillum fungus(with higher similarity with Penicillum dodgei);Through the further check procedures,it was determined that the strains FECH-050 and FECH-112 were the same ones(with 100%similarities);They all belonged to Aspergillus fungi(with higher similarity with Aspergillus lacticoffeatus).The strain FEDT-122 and the strain FEDT-866 reported previously were the same ones(with 100%similarities)with higher similarity with Aspergillus tubigensis.Most candidate strains still have no siderophores producing reports.2 strains were selected for amplified cultivation,fermentation extract pretreatment,the separation and purification of the extract,compound structure database quick searching works.20 pure compounds were obtained.After the searching process with nuclear magnetic resonance carbon spectrum database of ShangHai Microspectrum Technology Co.,Ltd.The chemical structures of 9 compounds showed the related matching informations.Using the compounds "siderophore A" and "siderophore B”obtained from previous works as materials,their effects on the prokaryotic microbial community structure of two different soil samples was investigated at pure culture and in situ free cultivation level.The results indicated that,with the exogenous intervention of secretory type siderophores,the soil microbial community structure could be changed.The two compounds could improve the relative abundance of Acidobacteria,Actinobacteria and Firmicutes and,in contrast,reduce the relative abundance of Bacteroidetes and Chloroflex in both soil samples.However,the effects of"siderophore A" and "siderophore B" on the microorganisms of Gemmatimonadetes were contrary.These phenomena showed the rather obvious regularity in the family level and above.Finally,after the clinical drug resistance bacteria inhibition experiments,it was also proved that the effects of the secretory siderophore on microorganisms(communities)could be mediated by iron ions.Through the work of this project,the research program of microbial siderophore was established,and the relationship between secondary metabolites and environmental microorganisms was preliminarily explored.It is laid the foundation for the further researches as ecological restoration for heavy metal pollution environment,remediation for agricultural soil microbial diversity,clinical pathogen control and so on through this work.