Homogenization of Streptococcus for Enzymatic Activity Measurements

Instrument: Precellys® 24 with Cryolys

Sample: Concentrated Streptococcus thermophilus cells


  • Add concentrated S. thermophilus cells to the 2 ml tough microorganism lysing kit.
  • Add 50 mM tris/HCl buffer, pH7*
  • Run the Precellys at 6800 rpm for 3 x 30 sec with 30 sec breaks.
  • Centrifuge at 15,000 x g for 10 minutes at 4°C.

In this instance, the user was looking to assess enzymatic activity.  You may substitute another buffer which is appropriate for your application.


Protein content was measured within the total cell extract by Bradford assay.  Enzyme activities (β-galactosidase and lactate dehydrogenase) were measured spectrophotometrically.

Enzyme activity measurements of S. thermophilus

β-galactosidase (a) and lactate dehydrogenase (b) activities of S. thermophilus wild-type cells (white bars) and A19(Δppc;ΔcarB) mutant cells (grey bars) grown in enriched CO2 or N2 atmosphere.