Figure 2.

Exogenous DNA provides a nutrient source for P. aeruginosa and can rescue the growth of a purine-deficient mutant. (A) Bacterial cells were incubated with 10 to 900 µg/mL herring DNA, as an exogenous purine source, without enzymatic digestion. (B) Bacterial cells were incubated with 10 to 900 µg/mL herring DNA with enzymatic digestion. (C) Relative bacterial abundance of wild-type and purine-deficient mutant (purC::tn) of P. aeruginosa in co-culture with JE2 or exogenous DNA. Cells in co-culture with JE2 or eDNA were normalized to the respective numbers in monoculture. (D) Relative fitness of purine-deficient mutant (purC::tn) of P. aeruginosa in co-culture with JE2 or eDNA compared to the growth of wildtype P. aeruginosa, PA14, in co-culture with JE2 or eDNA, respectively. Here, the relative numbers of purC::tn mutant were calculated by normalizing to the wild-type PA numbers in respective co-culture conditions. Error bars represent SEM of data derived from at least three biological replicates on different days, and experiments were performed in technical triplicates each day. The statistical comparison was done between the purC::tn mutant and PA14 strains (not shown here) in their respective co-culture conditions. Here, ‘’*’’ designates p < 0.05, ‘’**’’ designates p < 0.005, ‘’***’’ designates p < 0.0005, ‘’****’’ designates p < 0.0001 depicted by two-tailed unpaired Student’s t-test, and ns denotes not significant. The concentration of the exogenous DNA is in µg/mL.