FIGURE 5.

pho4 mutant is replaced by wild type strain in mixed cultures. (A) Exponentially growing SFY87-GFP/SFY87-dTOM2 (gray circles) and SFY87-GFP/pho4-dTOM2 (black square) strains were mixed to equal amount to 0.2 O.D. in YPD medium. Samples were collected at different time points and spread on SD plates to differentiate and count both types of colonies. After 24 h of growth a part of the culture was refreshed to new pre-warmed YPD medium and followed on time (dashed line). Fitness Relative Index was represented as function of time. (B) Mixed cultures were observed under fluorescent microscopy and representative samples are shown. (C) In parallel, cultures growth was determined as O.D.: (A_{260 nm}) and represented as function of time. (D) Balanced SFY87-GFP/SFY87-dTOM2 (gray circles), SFY87-GFP/pho4-dTOM2 (black square) mixed cell suspensions were challenged with 0.6 mM GSNO and incubated at 37°C. Samples were taken at different time points and spread on SD plates for CFUs count. Viability Relative Index was calculated as the ration between percentage of viable cells and the percentage of cells in the initial inoculum. Data from single cultures of wild type and pho4 mutant exposed to the same treatment were similarly analyzed. pho4/wt represent the Viability Relative Index calculated from single cultures. The graph shows the media ± SEM of three independent experiments. Statistical significance was determined using the Sidak-Bonferroni method, ^∗∗∗p < 0.001.