Eleven strains of lactobacilli were isolated from fermented milk of 9 companies. They were classified
3strains as L. bulgaricus, 2 strains as L. plantarum, 2 strains as L. cellobiosus, I strain as L. lactic, I strain as L. acidophilus, I strain as L. casei subsp. casei and 1 strain as L. casei subsp. tolerance. And these strains were examined for drug resistance, transferability and transfer frequency of R, plasmid.
Most of isolates were sensitive to tetracycline(TC), penicillin(PC), arid erythromycin(EM), but some strains were resistant to strepomycin(SM;, chloramphenicol(CP), ampicillin(AP), kanamycin(KM)d nalidixic acid(NA).
All of isolates were resistant to two or more drugs and 6 different drug resistant patterns were found. The most frequently encountered patterns were NA AP CP SM´KM(a strains) followed by NA AP CP KM(2 strains), NA AP CP -"´M(1 strain), NA AP CP(1 strain), NA CP(1 strain) and NA AP(1 strain).
Transfer experiment of drug resistance showed that of all 11 resistant strains, 9 strains transferred R plasmid determining AP(6 strains) or AP SM (3 strains) to a recipient, E. coli ML 1410 strain with 2.8 x10-5-1.5x10-1% of transfer.
These results indicate that 1actobacilli conjugally transfer their resistance to E. coli
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