Subject: Could there be mini black holes less then the plank mass black holes?

I read in many articles that the black hole can not weigh less then 22 
micrograms, however if we assume that the assumptions of extra demensions are 
correct where the gravity becomes a stronger force at smaller scales, I can't 
find the information and want to know on whether the black hole can have less 
mass then 22 micrograms, and whether the cosmic rays and future colliders like 
LHC in Cern will produce mini black holes that are less then 22 micrograms 
(plank mass at 4 dementional space time)or mini black holes less then 22 
micrograms cannot exist under any circumstances even with extra demensions 
available? 

Re: Could there be mini black holes less then the plank mass black holes?