Question

I want to add resazurin to my media as an anaerobic indicator.

To my understanding, the resazurin is blue when first added to the media, then turns pink after autoclaving, and finally it turns colorless when adding a reducing solution (sulfide in my case). However, I’m having trouble to make the media change from blue to pink. I’ve autoclaved and it’s still blue. My media contains KCl, NH4Cl, KH2PO4, Na2SO4, NaHCO3. I'll add sulfide and other metals after autoclaving.Should I flush my media before autoclaving?

Answer 1

The media is not changing from blue to pink because the reducing agent has not been added yet. Autoclaving alone will not cause the media to turn pink.

Step-by-step explanation:

The media is not changing from blue to pink even after autoclaving because the reducing agent (sulfide) has not been added yet. Autoclaving alone will not cause the media to turn pink.

The color change from blue to pink occurs when the reducing agent reacts with resazurin. Therefore, there is no need to flush the media before autoclaving.

Once you add the sulfide and other metals to the media after autoclaving, it should cause the resazurin to turn pink. The absence of the reducing agent is likely the reason why the media is still blue at this stage.