1. Put ~1-2g of pellets of frozen cells in the 50 ml stain less jars previously immersed in the liquid nitrogen until it stops boiling.
2. Close the jars. Do not screw the lid tightly.
3. Insert the jars into a Retsch Mixer Mill MM301, and beat for 5 times, 3’ at 30 beats per second. Between each beating immerse the jars in liquid nitrogen to cool. Efficiency of cell breakage can be observed in a microscope.
4. Transfer a cell powder back into 50 ml tube pre-cooled in liquid nitrogen. Be sure that there is no residual liquid nitrogen left in the tube.
NOTE> Cell powder can be maintained at –80ºC for long time at this stage.
