Effect of Kanamycin Sulfate and Gentamicin on Growth of Probiotics

Abstract

Effect of kanamycin sulfate and gentamicin on growth of Lactobacillus acidophilus, Bifidobacterium bifidum, Lactobacillus casei, Lactobacillus rhamnosus and Lactobacillus bulgaricus was studied by measuring the optical density at 600nm and pH using MRS broth as the control. The addition of kanamycin sulfate (%, w/v) was 0.0025, 0.005, 0.0075 and 0.01 and the addition of gentamicin(U/ml) was 48, 72, 144, 192 and 240. Results were as follows: addition of kanamycin sulfate at the concentration above 0.0025% has a significant inhibition on the growth of B. bifidum and has no influence on the other four probiotics at incubation12h or 24h. The optimum selective concentration of kanamycin sulfate in MRS media was 0.005% for selective enumeration of B.bifidum. Addition of gentamicin at the concentration above 240U/ml has a significant inhibition on the growth of L. bulgaricus at incubation 24h. Addition of neomycin sulfate in MRS can use to realize selective enumeration of L. bulgaricus in yogurt