The addition of prebiotic in food today is mostly done. It is based on the ability of prebiotic to support the growth of probiotic. Inulin is a carbohydrate that serves as an effective prebiotic that cannot be digested by digestive enzymes. The purpose of this research is to assess utilization of inulin from several types of tubers include dahlia tubers, yam tu- bers, and gembili tubers as a source of prebiotic that tested in probiotic bacteria (L. casei and L. plantarum). The study used a Randomized Block Design method with two factors, the type of probiotic isolate and inulin extract from tubers. The result shows that the best treatment is isolates of L. casei obtained in the fermentation medium with the addition of inulin from gembili tubers. The best treatment has the following characteristics: an increase in total LAB 2.71 × 10¹⁰ cfu/ml, 1.50% total acid, pH 2.05 and the total sugars are 3.11%. Whereas in isolates of L. plantarum, the best treatment in the fermentation medium is with the addition of inulin from dahlia tubers. The LAB reaches 2.80 × 10¹⁰ cfu/ml, 1.29% total acid, pH 2.24 and 2.05% total sugars.