I am using Pikovskaya and NBRIP media for phosphate solubilizing bacteria culture. Both media contain tri-calcium phosphate which is insoluble in water. As result, while using broth culture, there is a massive settlement of tri-calcium phosphate at the bottom of the flask.
Yes, it is normal. Tri-calcium phosphate is intentionally used as an insoluble source of phosphate to test the ability of phosphate-solubilizing bacteria to solubilize it. The goal of using TCP is to provide a challenge for PSB to solubilize it by producing organic acids or other mechanisms.
Consider to keep the flask on shaker at 100 - 120 rpm at 28 - 30 degrees celsius.
Sai Shiva Krishna Prasad Vurukonda Thanks for your answer. Can you please discuss one more thing? For counting colony forming units (CFU/ml), I am using NBRIP media and incubating at room temperature (25 degree) due to technical limitations. However, I am not getting good colony. What's your opinions/suggestions about this?
Md Rafique Uddin Could be many reasons,
1. Try to increase the temperature to 28 to 30
2. Check the pH of the media every day, if solution becomes too acidic it is obvious resulting in the lower CFU.
3. Also, how regulary are you checking, check in replicates.