engleski

Differences in the Influence of recA and RecB mutants on GASP Phenomenon in Escherichia coli

Nonsporogenic bacteria have evolved systems that enable them to use nutrients very efficiently, sustaining high growth rate during the period of feast, as well as to survive in the absence of nutrients. During prolonged stationary phase mutants with increased fitness express growth advantage in stationary phase” (GASP) enabling them to grow and displace the parent as the majority population. Three GASP mutants, two in the global gene regulators, rpoS and lrp, and the third in sgaA gene as the result of genomic rearrangement, have been found until now. The purpose of our investigation was to analyze the mixed populations of Escherichia coli and Salmonella enterica serovar Typhimurium during the prolonged period of carbon starvation due to the evaluation of the GASP phenomenon and its dependents of functional recA, and recB genes. In a typical GASP competition experiment, cells from a 10-day-old culture are inoculated as a numerical minority (1:10 and 1:100 vol/vol) into a young (1-day-old) culture. The mutant strains carry unique antibiotic resistance markers allowing each to be distinguished. The mixture of one-day-old culture of S. enterica or E. coli with ten-day-old cells of mutant recA E. coli as minority did not show the GASP phenomenon. However, when old culture consisted of null mutant recB of isogenic E. coli the strong GASP phenotype has been expressed.

growth advantage in stationary phase; Escherichia coli; Salmonella enterica; recA gene; recB gene

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