The bifidobacteria group are the most common probiotics found in the large intestine. They are comparatively delicate however, and their numbers can be depleted by toxins in the intestines or by other stressors. Lactobacillus sporogenes is a probiotic strain uniquely “pre-encapsulated” in spores that resist the action of antibiotics and gastric juices. Lyophilized (freeze-dried).