Plasmids loss effect on characteristics of bacterium Lactobacillus brevis L62

Ispitivana je mogućnost uklanjanja plazmida iz bakterijskih stanica Leuconostoc mesenteroides L3, Lactobacillus brevis L62 i Lactobacillus plantarum L73 pomoću lizozima. Praćen je rast bakterija mliječne kiseline nakon izlaganja lizozimu u siromašnoj i bogatoj tekućoj hranjivoj podlozi te pojava GASP (eng. growth advantage in stationary phase) fenotipa u sojeva L. brevis L62 naspram enterobakterija Escherichia coli MG1655 ili Salmonella enterica serotip Typhimurium. Izlaganjem stanica bakterije L. brevis L62 lizozimu došlo je do gubitka dva od tri plazmida dok u ostalih proučavanih bakterija mliječne kiseline nije uočen gubitak genetičkog materijala. Praćenjem preživljenja bakterijskih stanica tijekom produljene stacionarne faze rasta, ustanovljen je bolji rast stanica roditeljskog soja L. brevis L62 u usporedbi sa stanicama izlaganih lizozimu. Bakterijske stanice L. brevis L62 izlagane lizozimu, za razliku od roditeljskih, ne pokazuje fenotip GASP u odnosu na E. coli dok oba soja pokazuju jaki fenotip GASP u odnosu na S. enterica serotip Typhimurium.Lysozyme effect on loss of plasmids has been investigated in bacterial strains Leuconostoc mesenteroides L3, Lactobacillus brevis L62, and Lactobacillus plantarum L73. Growth of strains which were and were not treated with lysozyme was monitored in minimal MML, and rich MRS medium, as well as the appearance of Growth Advantage in Stationary Phase (GASP) phenomenon in mixed populations of L. brevis L62 and Escherichia coli MG1655 or Salmonella enterica serovar Typhimurium. The results of this study demonstrate loss of two out of three plasmids in L. brevis L62 after lysozyme treatment, whereas in other lactic acid bacteria the loss of genetic material had not taken place. Monitoring the surviving strains during the prolonged stationary phase, better growth of parental cells of L. brevis L62 has been determined in comparison to the cells treated with lysozyme. Bacterial cells L. brevis L62 treated with lysozyme, as opposed to parental cells, do not show GASP phenotype compared to E. coli, while both strains show strong GASP phenotype compared to S. enterica serovar Typhimurium