I prepared medium consisted of
KH2PO4 and Na2HPO4,
NaCl,
(NH4)2SO4
PPG-2000(polypropylene glycol 2000).

But the solution became cloudy after autoclave. I suspended PPG-2000 degraded and caused the problem. Any explanation?

Any other antifoam which is easy to autoclave?

Thank you

Kane

PPG 2025 remains clear.
I sterilise the antifoam separately, and add when necessary.

Have you attempted to sterilise PPG2000 separately to confirm that this is causing the problem?

Also, is there any reason why you need to repeatedly autoclave the antifoam instead of just adding a 'fresh' volume each time.

Could you try sterilization by filtration for this application?

The only downfall to using filters is cost or incompatibility such as protein binding to different filter types.