engleski

The role of Lactobacillus brevis L62 plasmids during prolonged stationary phase

In the state of starvation bacteria spend most of their time in a natural environmental. Starvation makes bacterial evolution possible in scantily condition. Stressful environment can result in selection of mutants that express growth advantage during starvation period. Growth advantage in stationary phase (GASP) is the term used to describe this phenomenon. The aim of this work was to carry out the curing of bacteria Lactobacillus brevis L62 which contains three plasmids, to examine the role of removed plasmids considering growth in rich MRS and minimal MML medium, as well as their coexisting with enterobacteria, Escherichia coli MG1655 or Salmonella enterica serovar Typhimurium, during long term cultivating. Under the influence of lysozime in concentration of 10 mg per ml during 24 hours under the temperature of 37 C, two smaller plasmids have been removed from L. brevis L62, while the biggest plasmid remained intact. Monitoring the surviving strains in minimal MML medium, during the prolonged stationary phase, better growth of the L. brevis L62T cells, lacking two plasmids, has been determined in comparison to the parental cells. Furthermore, in mixed cultures bacterial cell of L. brevis L62T, as opposed to parental cells, do not show GASP phenotype with E. coli, while both strains show strong GASP phenotype during coexistence with S. enterica.

GASP phenotype; Escherichia coli; Salmonella enterica; Lactobacillus brevis

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