Comparision of Antimicrobial Activities and Antibiotic Resistance of Lactobacillus Rhamnosus and Lactobacillus Acidophilus before and after Co-cultured

Lactic acid bacteria (LAB) have the important role in general health, providing a beneficial micro flora in the intestinal tract. The tested Lactobacillus acidophilus VTCC-B-702 and Lactobacillus rhamnosus ATCC 11443 were grown individually and co-cultured together in the same environment. Agar-well diffusion test was performed to determine the antibiotic susceptibility and antimicrobial activity. Two tested LAB exhibited the sensitivity to ampicilin and tetracycline at 5×10-3 to 1×10-2 (mg/ml), but resistant at 5×10-4 (mg/ml). L. acidophilus was resistant to erythromycin at all concentration, but L. rhamnosus was sensitivity to erythromycin at 5x10-3 to 1x10-2 (mg/ml), but resistant at 5×10-4(mg/ml). After co-cultured, both of these microrganisms were resistant to erythromycin. This action showed there were erythromycin resistant determinant from L. acidophilus to L. rhamnosus. The antimicrobial activities were also tested on Escherichia coli, Staphylococcus aureus, Salmonella typhi, Pseudomonas aeruginosa. The effects showed the synergy except on Escherichia coli.