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MINIMAL SALT MEDIUM - DIESEL DEGRADATION (Oct/21/2010 )

HI everybody.
I have the following question.
I am growing by bacteria in MSM of the following composition:
Minimum salts medium (MSM) was a mixture of solutions A, B and C.
Solution A contained (per 400 ml) 16 g of NH4NO3, 18.8 g of KH2PO4, 0.476 g of Na2HPO4, and 0.04 g of CaCl2 2H2O. This solution was adjusted to pH 7.0 with NaOH.
Solution B contained (per 400 ml) 4 g of MgSO4 7H2O, and 0.04 g of MnSO4 7H2O.
Solution C contained (per 400 ml) 0.03 g of FeSO4 7H2O.
10 ml of solution A mixed with 60 ml of distilled water, 10 ml of solution B, and 20 ml of solution C were separately autoclaved at 121C for 20 min, and then they were mixed.
I observe that after autoclaving and mixing a red sedimentation occurs.
This medium is used for growing bacteria with diesel and monitoring the degradation rates.
Also this sedimentation affects my O.D measurements.
I am waiting for your remarks


Gorens

-gorens-

Do you see the sedimentation right after autoclaving (not mixed) or after you mixed them?

It could be some sort of percipitationreaction.

-pito-

pito on Thu Oct 21 10:49:58 2010 said:


Do you see the sedimentation right after autoclaving (not mixed) or after you mixed them?

It could be some sort of percipitationreaction.

Just after I autoclave solution C ( most probably due to the iron content).
Do you have any recommendations for alternative Minimal mediums for the described purpose?

Regards,

gorens

-gorens-

Right FeSo4 precipitates when autoclaved. We usually filter-sterilise it (or a stock solution which can be pipetted directly into the cooled agar medium.

-gebirgsziege-