Batmanager

This year in college I'm given some free time in lab to work on some studies of my own. I've decided to look at several well-known Irish probiotic brands by testing the CFU of their probiotic culture and comparing it to their labelled value. How would I go about this? Isolation of probiotic from yoghurt culture? Inoculate on MRS agar? Addition of bile salts to determine if they would survive? Concentration of added bile salt? Useful research papers? I'm having trouble finding anything online. Any help would be greatly appreciated. Thanks.