Dear Alzahar,

Are you confident that your microbe is capable of producing a siderophore? I am asking this because many bacteria (including the pseudomonads) use similar non-ribosomal synthases (NRS) to produce cyclic lipopeptides that act as surfactants - and Blue Agar (CAS) is one of the assays to look for this (NRS genes are easy fo spot in genomes, but determining what product they produce is more difficult and it is not always clear if they are producing siderophores or surfactants or antibiotics).

You can easily determine if your microbe is producing a surfactant by preparing some cell-free culture supernatant (simply pellet the cells by centrifugation) and placing a 10 uL droplet on a clean glass or plastic (e.g., petri dish) surface. If these is no surfactant (or if this was your sterile growth medium) the droplet will retain an almost perfect hemispherical shape, as the liquid has a high (interfacial) surface tension.

If you microbe is producing a surfactant, the drop will 'collapse' to form a very thin puddle, often with very irregular edges, beagles the surface tension has been dramatically reduced.

Andrew

Thank you for your response @andrew If it does produce a surfactant other than siderophore then In that case how do i confirm its siderophore producing ability ?