Preparing media for growing magnetospirillium gryphiswalden has been a real pain in the neck. Soil or pond based bacteria are fastidious organisms that are fussy. I had to go back to basics and try to make up the media of the stock provider. The pink colour is produced when mixing the oxidation-reduction indicator "resazurin" with potasium phosphate salt.
And this is just to make up the base...making vitamin and trace element solution was more involved.
After mixing, adjusting pH, sterilising and combining the various solution (base, vitamin, trace elements, electron donor and carbon source) parts we finally end up with a light pink/violet media. By adding nitrogen gas to a sealed vial, the media was ready to be inoculated. But will they grow??!