I will be growing several different bacteria in M9 minimal iron-free media in order to promote siderophore production. After several days of growth in M9 broth, the cells will be removed by filter sterilizing. I am interested in quantifying the amount of siderophores present in the resulting solution but will not be able to perform the necessary assay for some time. Therefore, I am wondering how stable the siderophores would be in this solution and how it should be stored (i.e. 4C or -20C?) until quantification can be completed.
Thanks for your help!