So I've been doing biochem research on bacterial biodegradation of exotic organic compounds. Based on a lot of research I've done, a lot of biodegradation pathways involve step-by-step mono-oxygenation reactions catalyzed by Cytochrome P450 enzymes (which contain a ferrous heme group) and redox partners (usually iron-sulfur proteins). I've been incubating bacteria in liquid media with samples of solid organic waste generated by our university's undergraduate organic chemistry lab as a sole carbon source, but there was no degradation. Then I looked at the chemical profiles of the media I was using and found there was no iron in them. I tried adding tiny amounts of Ferrous Sulfate (FeSO4) to the liquid solution but it quickly precipitates; even a few sand-sized grains per mL and these white cloudy chunks forms and it looks like tiny specs of rusty iron fall to the bottom. I tried adjusting the pH of the solution to prevent precipitation but it didn't work. Is anyone aware either of an iron-salt that will dissolve in water? And if not, how can I get ferrous sulfate to evenly dissolve in water without clouding or precipitation?