engleski

GASP phenomenon and chromosomal rearrangments in mixed cultures of Escherichia coli and Salmonella enterica

Microorganisms 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. The ability of Escherichia coli to grow during carbon starvation in stationary phase has been termed the Growth Advantage in Stationary Phase (GASP) phenotype. The GASP phenomenon has been observed in range of microorganisms, including clinical isolates of E. coli and S. enterica. The occurrence of mutators among isolates of E. coli and S. enterica is up to 10%. The resulting mutants with increased fitness express GASP phenotype enabling them to grow and displace the parent as the majority population. The aim of our investigation was to analyze mixed populations of E. coli K12 and S. enterica serovar Typhimurium during the prolonged period of carbon starvation due to the evaluation of the GASP phenomenon. The mixture of one-day-old culture of S. enterica and sixteen-day-old cells of E. coli as minority did not show the GASP phenomenon. The same results were obtained when the mixture consisted of S. enterica as a minority cells. When we introduced isogenic mutants resistant to streptomycin or nalidixic acid the GASP phenomenon was observed. Obviously, this phenomenon is caused by combination of random mutation due to increase range of the mutator cells, and selection to growth inhibitors, streptomycin or nalidixic acid. Additionally, in cells with GASP phenotype the chromosomal rearrangements were determined by PFGE.

GASP; chromosomal rearrangements

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