Dear All

I tested siderophore production of Bacillus sp. on CAS media. some bacterial strains produced orange yellow hallow (positive for siderophore), howevre I also observed slightly pale and blue hallow around some strains, and some colonies also look yellow orange of CAS media but with no orang hallow around them after 3 days of incubation......... what you say which of my strains with pale blue hallow are siderophore producer in given picture which represents the siderophore production after 7 days of incubation..........please have a look on file attached