Comparing the efficacy of plasmid curing agents in Lactobacillus acidophilus.

This study was mainly focused on plasmid profiling and plasmid characterisation of Lactobacillus acidophilus isolated from molasses. The secondary objective was to observe the efficacy of the plasmid curing agents acriflavine, ethidium bromide, novobiocin and SDS on L. acidophilus. Plasmid-free strains and cured derivatives harbouring only a single plasmid (6.2 kbp) were also obtained. Treatment of L. acidophilus with novobiocin at concentrations of 2.4 µg/ml could produce a large number of chloramphenicol- variants at a very high frequency (4.6%). These curing data confirmed that novobiocin acts as an effective curing agent for L. acidophilus.