Comparison of antimicrobial resistance between the type strain of Lactococcus lactis and isolates from coastal environments

Abstract

To ensure the safety of dairy products, a comparison was made between coastal‐derived Lactococcus lactis strains and the type strain regarding antimicrobial resistance (AMR) and their genes. The test discs revealed that the AMR of 31 strains against streptomycin, gentamicin and kanamycin was higher than that of the type strain. The clear zone ratio of the type strain to that of Himuka‐SU2 was 3.0–3.5. However, both strains exhibited identical AMR genes. Pre‐incubation in broth containing 3.4% (w/v) NaCl increased the AMR of the type strain compared to the Himuka‐SU2 strain. These results are significant for the development of starters for fermented milk.