I am planning to prepare a lysate of Lactobacillus rhamnosus GG (LGG)by sonication, and test this lysate in both in mammalian experiment, does any one have suggestion regarding power, time and number of pulses to go with?? did any one succeeded in sonicating LGG?

I am planning to use BCA protein assay to check protein yield after sonication.

I used to do the sonication at 100 amplitude for 3 min on ice using bandelin sonoplus sonicater. I used both 10 ml and 5 ml bacteria in PBS, but I always have very low protein yield, so I am thinking that there is problem in my sonication.

I also plate the lysate on culture plate to make sure it is clear from any bacteria, and no bacterium was detected ( this step is done after filtration with 0.22 micro syringe filter) 

I really appreciate any suggestion that may help me with this issue