Dear Sendosa,

The best and recommended method to store a bacteria culture is to use 50% glycerol stock.

Please follow these steps;

1: Make a 50% glycerol stock and store it in 4 °C.

2: Take a screw tight Vail (autoclaved, 1.5 mL).

3: Pour 300 uL from the bacteria culture and 900 uL from 50% glycerol stock, in the vail inside a clean-bench. Please make this stock inside clean-bench to avoid any contamination.

4: Mix well and store in -80 °C (-20 °C will also work)

5: You can keep this frozen stock up to 6 months (recommended).

Note: Glycerol protects the bacteria cells from damage due to very low temperature. Please see literature for more details.

I hope this helps you out.

Best,

Salman Shah.

Please see the attachement file. I think it shall be helpful.

You can culture pure colony in agar plate and keep it at 4°C or you can prepare 50% glycerol stock by adding equal volume of absolute glycerol and culture broth and store it at -80°C.